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third-party-mirror/openjdk/jdk25u/refs/heads/master/./src/java.base/share/classes/java/lang/String.java
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/*
* Copyright (c) 1994, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
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*/
package java.lang;
import java.io.ObjectStreamField;
import java.io.UnsupportedEncodingException;
import java.lang.annotation.Native;
import java.lang.foreign.MemorySegment;
import java.lang.foreign.ValueLayout;
import java.lang.invoke.MethodHandles;
import java.lang.constant.Constable;
import java.lang.constant.ConstantDesc;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Formatter;
import java.util.List;
import java.util.Locale;
import java.util.Objects;
import java.util.Optional;
import java.util.Spliterator;
import java.util.function.Function;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import jdk.internal.util.ArraysSupport;
import jdk.internal.util.Preconditions;
import jdk.internal.vm.annotation.ForceInline;
import jdk.internal.vm.annotation.IntrinsicCandidate;
import jdk.internal.vm.annotation.Stable;
import sun.nio.cs.ArrayDecoder;
import sun.nio.cs.ArrayEncoder;
import sun.nio.cs.ISO_8859_1;
import sun.nio.cs.US_ASCII;
import sun.nio.cs.UTF_8;
/**
* The {@code String} class represents character strings. All
* string literals in Java programs, such as {@code "abc"}, are
* implemented as instances of this class.
* <p>
* Strings are constant; their values cannot be changed after they
* are created. String buffers support mutable strings.
* Because String objects are immutable they can be shared. For example:
* <blockquote><pre>
* String str = "abc";
* </pre></blockquote><p>
* is equivalent to:
* <blockquote><pre>
* char data[] = {'a', 'b', 'c'};
* String str = new String(data);
* </pre></blockquote><p>
* Here are some more examples of how strings can be used:
* <blockquote><pre>
* System.out.println("abc");
* String cde = "cde";
* System.out.println("abc" + cde);
* String c = "abc".substring(2, 3);
* String d = cde.substring(1, 2);
* </pre></blockquote>
* <p>
* The class {@code String} includes methods for examining
* individual characters of the sequence, for comparing strings, for
* searching strings, for extracting substrings, and for creating a
* copy of a string with all characters translated to uppercase or to
* lowercase. Case mapping is based on the Unicode Standard version
* specified by the {@link java.lang.Character Character} class.
* <p>
* The Java language provides special support for the string
* concatenation operator (&nbsp;+&nbsp;), and for conversion of
* other objects to strings. For additional information on string
* concatenation and conversion, see <i>The Java Language Specification</i>.
*
* <p> Unless otherwise noted, passing a {@code null} argument to a constructor
* or method in this class will cause a {@link NullPointerException} to be
* thrown.
*
* <p>A {@code String} represents a string in the UTF-16 format
* in which <em>supplementary characters</em> are represented by <em>surrogate
* pairs</em> (see the section <a href="Character.html#unicode">Unicode
* Character Representations</a> in the {@code Character} class for
* more information).
* Index values refer to {@code char} code units, so a supplementary
* character uses two positions in a {@code String}.
* <p>The {@code String} class provides methods for dealing with
* Unicode code points (i.e., characters), in addition to those for
* dealing with Unicode code units (i.e., {@code char} values).
*
* <p>Unless otherwise noted, methods for comparing Strings do not take locale
* into account. The {@link java.text.Collator} class provides methods for
* finer-grain, locale-sensitive String comparison.
*
* @implNote The implementation of the string concatenation operator is left to
* the discretion of a Java compiler, as long as the compiler ultimately conforms
* to <i>The Java Language Specification</i>. For example, the {@code javac} compiler
* may implement the operator with {@code StringBuffer}, {@code StringBuilder},
* or {@code java.lang.invoke.StringConcatFactory} depending on the JDK version. The
* implementation of string conversion is typically through the method {@code toString},
* defined by {@code Object} and inherited by all classes in Java.
*
* @author Lee Boynton
* @author Arthur van Hoff
* @author Martin Buchholz
* @author Ulf Zibis
* @see java.lang.Object#toString()
* @see java.lang.StringBuffer
* @see java.lang.StringBuilder
* @see java.nio.charset.Charset
* @since 1.0
* @jls 15.18.1 String Concatenation Operator +
*/
public final class String
implements java.io.Serializable, Comparable<String>, CharSequence,
Constable, ConstantDesc {
/**
* The value is used for character storage.
*
* @implNote This field is trusted by the VM, and is a subject to
* constant folding if String instance is constant. Overwriting this
* field after construction will cause problems.
*
* Additionally, it is marked with {@link Stable} to trust the contents
* of the array. No other facility in JDK provides this functionality (yet).
* {@link Stable} is safe here, because value is never null.
*/
@Stable
private final byte[] value;
/**
* The identifier of the encoding used to encode the bytes in
* {@code value}. The supported values in this implementation are
*
* LATIN1
* UTF16
*
* @implNote This field is trusted by the VM, and is a subject to
* constant folding if String instance is constant. Overwriting this
* field after construction will cause problems.
*/
private final byte coder;
/** Cache the hash code for the string */
@Stable
private int hash; // Default to 0
/**
* Cache if the hash has been calculated as actually being zero, enabling
* us to avoid recalculating this. This field is _not_ annotated @Stable as
* the `hashCode()` method reads the field `hash` first anyhow and if `hash`
* is the default zero value, is not trusted.
*/
private boolean hashIsZero; // Default to false;
/** use serialVersionUID from JDK 1.0.2 for interoperability */
@java.io.Serial
private static final long serialVersionUID = -6849794470754667710L;
/**
* If String compaction is disabled, the bytes in {@code value} are
* always encoded in UTF16.
*
* For methods with several possible implementation paths, when String
* compaction is disabled, only one code path is taken.
*
* The instance field value is generally opaque to optimizing JIT
* compilers. Therefore, in performance-sensitive place, an explicit
* check of the static boolean {@code COMPACT_STRINGS} is done first
* before checking the {@code coder} field since the static boolean
* {@code COMPACT_STRINGS} would be constant folded away by an
* optimizing JIT compiler. The idioms for these cases are as follows.
*
* For code such as:
*
* if (coder == LATIN1) { ... }
*
* can be written more optimally as
*
* if (coder() == LATIN1) { ... }
*
* or:
*
* if (COMPACT_STRINGS && coder == LATIN1) { ... }
*
* An optimizing JIT compiler can fold the above conditional as:
*
* COMPACT_STRINGS == true => if (coder == LATIN1) { ... }
* COMPACT_STRINGS == false => if (false) { ... }
*
* @implNote
* The actual value for this field is injected by JVM. The static
* initialization block is used to set the value here to communicate
* that this static final field is not statically foldable, and to
* avoid any possible circular dependency during vm initialization.
*/
static final boolean COMPACT_STRINGS;
static {
COMPACT_STRINGS = true;
}
/**
* Class String is special cased within the Serialization Stream Protocol.
*
* A String instance is written into an ObjectOutputStream according to
* <a href="{@docRoot}/../specs/serialization/protocol.html#stream-elements">
* <cite>Java Object Serialization Specification</cite>, Section 6.2, "Stream Elements"</a>
*/
@java.io.Serial
private static final ObjectStreamField[] serialPersistentFields =
new ObjectStreamField[0];
/**
* Initializes a newly created {@code String} object so that it represents
* an empty character sequence. Note that use of this constructor is
* unnecessary since Strings are immutable.
*/
public String() {
this.value = "".value;
this.coder = "".coder;
}
/**
* Initializes a newly created {@code String} object so that it represents
* the same sequence of characters as the argument; in other words, the
* newly created string is a copy of the argument string. Unless an
* explicit copy of {@code original} is needed, use of this constructor is
* unnecessary since Strings are immutable.
*
* @param original
* A {@code String}
*/
@IntrinsicCandidate
public String(String original) {
this.value = original.value;
this.coder = original.coder;
this.hash = original.hash;
this.hashIsZero = original.hashIsZero;
}
/**
* Allocates a new {@code String} so that it represents the sequence of
* characters currently contained in the character array argument. The
* contents of the character array are copied; subsequent modification of
* the character array does not affect the newly created string.
*
* <p> The contents of the string are unspecified if the character array
* is modified during string construction.
*
* @param value
* The initial value of the string
*/
public String(char[] value) {
this(value, 0, value.length, null);
}
/**
* Allocates a new {@code String} that contains characters from a subarray
* of the character array argument. The {@code offset} argument is the
* index of the first character of the subarray and the {@code count}
* argument specifies the length of the subarray. The contents of the
* subarray are copied; subsequent modification of the character array does
* not affect the newly created string.
*
* <p> The contents of the string are unspecified if the character array
* is modified during string construction.
*
* @param value
* Array that is the source of characters
*
* @param offset
* The initial offset
*
* @param count
* The length
*
* @throws IndexOutOfBoundsException
* If {@code offset} is negative, {@code count} is negative, or
* {@code offset} is greater than {@code value.length - count}
*/
public String(char[] value, int offset, int count) {
this(value, offset, count, rangeCheck(value, offset, count));
}
private static Void rangeCheck(char[] value, int offset, int count) {
checkBoundsOffCount(offset, count, value.length);
return null;
}
/**
* Allocates a new {@code String} that contains characters from a subarray
* of the <a href="Character.html#unicode">Unicode code point</a> array
* argument. The {@code offset} argument is the index of the first code
* point of the subarray and the {@code count} argument specifies the
* length of the subarray. The contents of the subarray are converted to
* {@code char}s; subsequent modification of the {@code int} array does not
* affect the newly created string.
*
* <p> The contents of the string are unspecified if the codepoints array
* is modified during string construction.
*
* @param codePoints
* Array that is the source of Unicode code points
*
* @param offset
* The initial offset
*
* @param count
* The length
*
* @throws IllegalArgumentException
* If any invalid Unicode code point is found in {@code
* codePoints}
*
* @throws IndexOutOfBoundsException
* If {@code offset} is negative, {@code count} is negative, or
* {@code offset} is greater than {@code codePoints.length - count}
*
* @since 1.5
*/
public String(int[] codePoints, int offset, int count) {
checkBoundsOffCount(offset, count, codePoints.length);
if (count == 0) {
this.value = "".value;
this.coder = "".coder;
return;
}
if (COMPACT_STRINGS) {
byte[] val = StringUTF16.compress(codePoints, offset, count);
this.coder = StringUTF16.coderFromArrayLen(val, count);
this.value = val;
return;
}
this.coder = UTF16;
this.value = StringUTF16.toBytes(codePoints, offset, count);
}
/**
* Allocates a new {@code String} constructed from a subarray of an array
* of 8-bit integer values.
*
* <p> The {@code offset} argument is the index of the first byte of the
* subarray, and the {@code count} argument specifies the length of the
* subarray.
*
* <p> Each {@code byte} in the subarray is converted to a {@code char} as
* specified in the {@link #String(byte[],int) String(byte[],int)} constructor.
*
* <p> The contents of the string are unspecified if the byte array
* is modified during string construction.
*
* @deprecated This method does not properly convert bytes into characters.
* As of JDK&nbsp;1.1, the preferred way to do this is via the
* {@code String} constructors that take a {@link Charset}, charset name,
* or that use the {@link Charset#defaultCharset() default charset}.
*
* @param ascii
* The bytes to be converted to characters
*
* @param hibyte
* The top 8 bits of each 16-bit Unicode code unit
*
* @param offset
* The initial offset
* @param count
* The length
*
* @throws IndexOutOfBoundsException
* If {@code offset} is negative, {@code count} is negative, or
* {@code offset} is greater than {@code ascii.length - count}
*
* @see #String(byte[], int)
* @see #String(byte[], int, int, java.lang.String)
* @see #String(byte[], int, int, java.nio.charset.Charset)
* @see #String(byte[], int, int)
* @see #String(byte[], java.lang.String)
* @see #String(byte[], java.nio.charset.Charset)
* @see #String(byte[])
*/
@Deprecated(since="1.1")
public String(byte[] ascii, int hibyte, int offset, int count) {
checkBoundsOffCount(offset, count, ascii.length);
if (count == 0) {
this.value = "".value;
this.coder = "".coder;
return;
}
if (COMPACT_STRINGS && (byte)hibyte == 0) {
this.value = Arrays.copyOfRange(ascii, offset, offset + count);
this.coder = LATIN1;
} else {
hibyte <<= 8;
byte[] val = StringUTF16.newBytesFor(count);
for (int i = 0; i < count; i++) {
StringUTF16.putChar(val, i, hibyte | (ascii[offset++] & 0xff));
}
this.value = val;
this.coder = UTF16;
}
}
/**
* Allocates a new {@code String} containing characters constructed from
* an array of 8-bit integer values. Each character <i>c</i> in the
* resulting string is constructed from the corresponding component
* <i>b</i> in the byte array such that:
*
* <blockquote><pre>
* <b><i>c</i></b> == (char)(((hibyte &amp; 0xff) &lt;&lt; 8)
* | (<b><i>b</i></b> &amp; 0xff))
* </pre></blockquote>
*
* <p> The contents of the string are unspecified if the byte array
* is modified during string construction.
*
* @deprecated This method does not properly convert bytes into
* characters. As of JDK&nbsp;1.1, the preferred way to do this is via the
* {@code String} constructors that take a {@link Charset}, charset name,
* or that use the {@link Charset#defaultCharset() default charset}.
*
* @param ascii
* The bytes to be converted to characters
*
* @param hibyte
* The top 8 bits of each 16-bit Unicode code unit
*
* @see #String(byte[], int, int, java.lang.String)
* @see #String(byte[], int, int, java.nio.charset.Charset)
* @see #String(byte[], int, int)
* @see #String(byte[], java.lang.String)
* @see #String(byte[], java.nio.charset.Charset)
* @see #String(byte[])
*/
@Deprecated(since="1.1")
public String(byte[] ascii, int hibyte) {
this(ascii, hibyte, 0, ascii.length);
}
/**
* Constructs a new {@code String} by decoding the specified subarray of
* bytes using the specified charset. The length of the new {@code String}
* is a function of the charset, and hence may not be equal to the length
* of the subarray.
*
* <p> The behavior of this constructor when the given bytes are not valid
* in the given charset is unspecified. The {@link
* java.nio.charset.CharsetDecoder} class should be used when more control
* over the decoding process is required.
*
* <p> The contents of the string are unspecified if the byte array
* is modified during string construction.
*
* @param bytes
* The bytes to be decoded into characters
*
* @param offset
* The index of the first byte to decode
*
* @param length
* The number of bytes to decode
*
* @param charsetName
* The name of a supported {@linkplain java.nio.charset.Charset
* charset}
*
* @throws UnsupportedEncodingException
* If the named charset is not supported
*
* @throws IndexOutOfBoundsException
* If {@code offset} is negative, {@code length} is negative, or
* {@code offset} is greater than {@code bytes.length - length}
*
* @since 1.1
*/
public String(byte[] bytes, int offset, int length, String charsetName)
throws UnsupportedEncodingException {
this(lookupCharset(charsetName), bytes, checkBoundsOffCount(offset, length, bytes.length), length);
}
/**
* Constructs a new {@code String} by decoding the specified subarray of
* bytes using the specified {@linkplain java.nio.charset.Charset charset}.
* The length of the new {@code String} is a function of the charset, and
* hence may not be equal to the length of the subarray.
*
* <p> This method always replaces malformed-input and unmappable-character
* sequences with this charset's default replacement string. The {@link
* java.nio.charset.CharsetDecoder} class should be used when more control
* over the decoding process is required.
*
* <p> The contents of the string are unspecified if the byte array
* is modified during string construction.
*
* @param bytes
* The bytes to be decoded into characters
*
* @param offset
* The index of the first byte to decode
*
* @param length
* The number of bytes to decode
*
* @param charset
* The {@linkplain java.nio.charset.Charset charset} to be used to
* decode the {@code bytes}
*
* @throws IndexOutOfBoundsException
* If {@code offset} is negative, {@code length} is negative, or
* {@code offset} is greater than {@code bytes.length - length}
*
* @since 1.6
*/
public String(byte[] bytes, int offset, int length, Charset charset) {
this(Objects.requireNonNull(charset), bytes, checkBoundsOffCount(offset, length, bytes.length), length);
}
/**
* This method does not do any precondition checks on its arguments.
* <p>
* Important: parameter order of this method is deliberately changed in order to
* disambiguate it against other similar methods of this class.
*/
private String(Charset charset, byte[] bytes, int offset, int length) {
if (length == 0) {
this.value = "".value;
this.coder = "".coder;
} else if (charset == UTF_8.INSTANCE) {
if (COMPACT_STRINGS) {
int dp = StringCoding.countPositives(bytes, offset, length);
if (dp == length) {
this.value = Arrays.copyOfRange(bytes, offset, offset + length);
this.coder = LATIN1;
return;
}
// Decode with a stable copy, to be the result if the decoded length is the same
byte[] latin1 = Arrays.copyOfRange(bytes, offset, offset + length);
int sp = dp; // first dp bytes are already in the copy
while (sp < length) {
int b1 = latin1[sp++];
if (b1 >= 0) {
latin1[dp++] = (byte)b1;
continue;
}
if ((b1 & 0xfe) == 0xc2 && sp < length) { // b1 either 0xc2 or 0xc3
int b2 = latin1[sp];
if (b2 < -64) { // continuation bytes are always negative values in the range -128 to -65
latin1[dp++] = (byte)decode2(b1, b2);
sp++;
continue;
}
}
// anything not a latin1, including the REPL
// we have to go with the utf16
sp--;
break;
}
if (sp == length) {
if (dp != latin1.length) {
latin1 = Arrays.copyOf(latin1, dp);
}
this.value = latin1;
this.coder = LATIN1;
return;
}
byte[] utf16 = StringUTF16.newBytesFor(length);
StringLatin1.inflate(latin1, 0, utf16, 0, dp);
dp = decodeUTF8_UTF16(latin1, sp, length, utf16, dp, true);
if (dp != length) {
utf16 = Arrays.copyOf(utf16, dp << 1);
}
this.value = utf16;
this.coder = UTF16;
} else { // !COMPACT_STRINGS
byte[] dst = StringUTF16.newBytesFor(length);
int dp = decodeUTF8_UTF16(bytes, offset, offset + length, dst, 0, true);
if (dp != length) {
dst = Arrays.copyOf(dst, dp << 1);
}
this.value = dst;
this.coder = UTF16;
}
} else if (charset == ISO_8859_1.INSTANCE) {
if (COMPACT_STRINGS) {
this.value = Arrays.copyOfRange(bytes, offset, offset + length);
this.coder = LATIN1;
} else {
this.value = StringLatin1.inflate(bytes, offset, length);
this.coder = UTF16;
}
} else if (charset == US_ASCII.INSTANCE) {
if (COMPACT_STRINGS && !StringCoding.hasNegatives(bytes, offset, length)) {
this.value = Arrays.copyOfRange(bytes, offset, offset + length);
this.coder = LATIN1;
} else {
byte[] dst = StringUTF16.newBytesFor(length);
int dp = 0;
while (dp < length) {
int b = bytes[offset++];
StringUTF16.putChar(dst, dp++, (b >= 0) ? (char) b : REPL);
}
this.value = dst;
this.coder = UTF16;
}
} else {
// (1)We never cache the "external" cs, the only benefit of creating
// an additional StringDe/Encoder object to wrap it is to share the
// de/encode() method. These SD/E objects are short-lived, the young-gen
// gc should be able to take care of them well. But the best approach
// is still not to generate them if not really necessary.
// (2)The defensive copy of the input byte/char[] has a big performance
// impact, as well as the outgoing result byte/char[]. Need to do the
// optimization check of (sm==null && classLoader0==null) for both.
CharsetDecoder cd = charset.newDecoder();
// ArrayDecoder fastpaths
if (cd instanceof ArrayDecoder ad) {
// ascii
if (ad.isASCIICompatible() && !StringCoding.hasNegatives(bytes, offset, length)) {
if (COMPACT_STRINGS) {
this.value = Arrays.copyOfRange(bytes, offset, offset + length);
this.coder = LATIN1;
return;
}
this.value = StringLatin1.inflate(bytes, offset, length);
this.coder = UTF16;
return;
}
// fastpath for always Latin1 decodable single byte
if (COMPACT_STRINGS && ad.isLatin1Decodable()) {
byte[] dst = new byte[length];
ad.decodeToLatin1(bytes, offset, length, dst);
this.value = dst;
this.coder = LATIN1;
return;
}
int en = scale(length, cd.maxCharsPerByte());
cd.onMalformedInput(CodingErrorAction.REPLACE)
.onUnmappableCharacter(CodingErrorAction.REPLACE);
char[] ca = new char[en];
int clen = ad.decode(bytes, offset, length, ca);
if (COMPACT_STRINGS) {
byte[] val = StringUTF16.compress(ca, 0, clen);;
this.coder = StringUTF16.coderFromArrayLen(val, clen);
this.value = val;
return;
}
coder = UTF16;
value = StringUTF16.toBytes(ca, 0, clen);
return;
}
// decode using CharsetDecoder
int en = scale(length, cd.maxCharsPerByte());
cd.onMalformedInput(CodingErrorAction.REPLACE)
.onUnmappableCharacter(CodingErrorAction.REPLACE);
char[] ca = new char[en];
int caLen;
try {
caLen = decodeWithDecoder(cd, ca, bytes, offset, length);
} catch (CharacterCodingException x) {
// Substitution is enabled, so this shouldn't happen
throw new Error(x);
}
if (COMPACT_STRINGS) {
byte[] val = StringUTF16.compress(ca, 0, caLen);
this.coder = StringUTF16.coderFromArrayLen(val, caLen);
this.value = val;
return;
}
coder = UTF16;
value = StringUTF16.toBytes(ca, 0, caLen);
}
}
/*
* Throws iae, instead of replacing, if malformed or unmappable.
*
* @param noShare
* {@code true} if the resulting string MUST NOT share the byte array,
* {@code false} if the byte array can be exclusively used to construct
* the string and is not modified or used for any other purpose.
*/
static String newStringUTF8NoRepl(byte[] bytes, int offset, int length, boolean noShare) {
checkBoundsOffCount(offset, length, bytes.length);
if (length == 0) {
return "";
}
int dp;
byte[] dst;
if (COMPACT_STRINGS) {
dp = StringCoding.countPositives(bytes, offset, length);
int sl = offset + length;
if (dp == length) {
if (noShare || length != bytes.length) {
return new String(Arrays.copyOfRange(bytes, offset, offset + length), LATIN1);
} else {
return new String(bytes, LATIN1);
}
}
dst = new byte[length];
System.arraycopy(bytes, offset, dst, 0, dp);
offset += dp;
while (offset < sl) {
int b1 = bytes[offset++];
if (b1 >= 0) {
dst[dp++] = (byte)b1;
continue;
}
if ((b1 & 0xfe) == 0xc2 && offset < sl) { // b1 either 0xc2 or 0xc3
int b2 = bytes[offset];
if (b2 < -64) { // continuation bytes are always negative values in the range -128 to -65
dst[dp++] = (byte)decode2(b1, b2);
offset++;
continue;
}
}
// anything not a latin1, including the REPL
// we have to go with the utf16
offset--;
break;
}
if (offset == sl) {
if (dp != dst.length) {
dst = Arrays.copyOf(dst, dp);
}
return new String(dst, LATIN1);
}
if (dp == 0) {
dst = StringUTF16.newBytesFor(length);
} else {
byte[] buf = StringUTF16.newBytesFor(length);
StringLatin1.inflate(dst, 0, buf, 0, dp);
dst = buf;
}
dp = decodeUTF8_UTF16(bytes, offset, sl, dst, dp, false);
} else { // !COMPACT_STRINGS
dst = StringUTF16.newBytesFor(length);
dp = decodeUTF8_UTF16(bytes, offset, offset + length, dst, 0, false);
}
if (dp != length) {
dst = Arrays.copyOf(dst, dp << 1);
}
return new String(dst, UTF16);
}
static String newStringNoRepl(byte[] src, Charset cs) throws CharacterCodingException {
try {
return newStringNoRepl1(src, cs);
} catch (IllegalArgumentException e) {
//newStringNoRepl1 throws IAE with MalformedInputException or CCE as the cause
Throwable cause = e.getCause();
if (cause instanceof MalformedInputException mie) {
throw mie;
}
throw (CharacterCodingException)cause;
}
}
private static String newStringNoRepl1(byte[] src, Charset cs) {
int len = src.length;
if (len == 0) {
return "";
}
if (cs == UTF_8.INSTANCE) {
return newStringUTF8NoRepl(src, 0, src.length, false);
}
if (cs == ISO_8859_1.INSTANCE) {
if (COMPACT_STRINGS)
return new String(src, LATIN1);
return new String(StringLatin1.inflate(src, 0, src.length), UTF16);
}
if (cs == US_ASCII.INSTANCE) {
if (!StringCoding.hasNegatives(src, 0, src.length)) {
if (COMPACT_STRINGS)
return new String(src, LATIN1);
return new String(StringLatin1.inflate(src, 0, src.length), UTF16);
} else {
throwMalformed(src);
}
}
CharsetDecoder cd = cs.newDecoder();
// ascii fastpath
if (cd instanceof ArrayDecoder ad &&
ad.isASCIICompatible() &&
!StringCoding.hasNegatives(src, 0, src.length)) {
if (COMPACT_STRINGS)
return new String(src, LATIN1);
return new String(src, 0, src.length, ISO_8859_1.INSTANCE);
}
int en = scale(len, cd.maxCharsPerByte());
char[] ca = new char[en];
int caLen;
try {
caLen = decodeWithDecoder(cd, ca, src, 0, src.length);
} catch (CharacterCodingException x) {
// throw via IAE
throw new IllegalArgumentException(x);
}
if (COMPACT_STRINGS) {
byte[] val = StringUTF16.compress(ca, 0, caLen);
byte coder = StringUTF16.coderFromArrayLen(val, caLen);
return new String(val, coder);
}
return new String(StringUTF16.toBytes(ca, 0, caLen), UTF16);
}
private static final char REPL = '\ufffd';
// Trim the given byte array to the given length
private static byte[] trimArray(byte[] ba, int len) {
if (len == ba.length) {
return ba;
} else {
return Arrays.copyOf(ba, len);
}
}
private static int scale(int len, float expansionFactor) {
// We need to perform double, not float, arithmetic; otherwise
// we lose low order bits when len is larger than 2**24.
return (int)(len * (double)expansionFactor);
}
private static Charset lookupCharset(String csn) throws UnsupportedEncodingException {
Objects.requireNonNull(csn);
try {
return Charset.forName(csn);
} catch (UnsupportedCharsetException | IllegalCharsetNameException x) {
throw new UnsupportedEncodingException(csn);
}
}
private static byte[] encode(Charset cs, byte coder, byte[] val) {
if (cs == UTF_8.INSTANCE) {
return encodeUTF8(coder, val, true);
}
if (cs == ISO_8859_1.INSTANCE) {
return encode8859_1(coder, val);
}
if (cs == US_ASCII.INSTANCE) {
return encodeASCII(coder, val);
}
return encodeWithEncoder(cs, coder, val, true);
}
private static byte[] encodeWithEncoder(Charset cs, byte coder, byte[] val, boolean doReplace) {
CharsetEncoder ce = cs.newEncoder();
int len = val.length >> coder; // assume LATIN1=0/UTF16=1;
int en = scale(len, ce.maxBytesPerChar());
// fastpath with ArrayEncoder implies `doReplace`.
if (doReplace && ce instanceof ArrayEncoder ae) {
// fastpath for ascii compatible
if (coder == LATIN1 &&
ae.isASCIICompatible() &&
!StringCoding.hasNegatives(val, 0, val.length)) {
return val.clone();
}
byte[] ba = new byte[en];
if (len == 0) {
return ba;
}
int blen = (coder == LATIN1) ? ae.encodeFromLatin1(val, 0, len, ba)
: ae.encodeFromUTF16(val, 0, len, ba);
if (blen != -1) {
return trimArray(ba, blen);
}
}
byte[] ba = new byte[en];
if (len == 0) {
return ba;
}
if (doReplace) {
ce.onMalformedInput(CodingErrorAction.REPLACE)
.onUnmappableCharacter(CodingErrorAction.REPLACE);
}
char[] ca = (coder == LATIN1 ) ? StringLatin1.toChars(val)
: StringUTF16.toChars(val);
ByteBuffer bb = ByteBuffer.wrap(ba);
CharBuffer cb = CharBuffer.wrap(ca, 0, len);
try {
CoderResult cr = ce.encode(cb, bb, true);
if (!cr.isUnderflow())
cr.throwException();
cr = ce.flush(bb);
if (!cr.isUnderflow())
cr.throwException();
} catch (CharacterCodingException x) {
if (!doReplace) {
throw new IllegalArgumentException(x);
} else {
throw new Error(x);
}
}
return trimArray(ba, bb.position());
}
/*
* Throws iae, instead of replacing, if unmappable.
*/
static byte[] getBytesUTF8NoRepl(String s) {
return encodeUTF8(s.coder(), s.value(), false);
}
private static boolean isASCII(byte[] src) {
return !StringCoding.hasNegatives(src, 0, src.length);
}
/*
* Throws CCE, instead of replacing, if unmappable.
*/
static byte[] getBytesNoRepl(String s, Charset cs) throws CharacterCodingException {
try {
return getBytesNoRepl1(s, cs);
} catch (IllegalArgumentException e) {
//getBytesNoRepl1 throws IAE with UnmappableCharacterException or CCE as the cause
Throwable cause = e.getCause();
if (cause instanceof UnmappableCharacterException) {
throw (UnmappableCharacterException)cause;
}
throw (CharacterCodingException)cause;
}
}
private static byte[] getBytesNoRepl1(String s, Charset cs) {
byte[] val = s.value();
byte coder = s.coder();
if (cs == UTF_8.INSTANCE) {
if (coder == LATIN1 && isASCII(val)) {
return val;
}
return encodeUTF8(coder, val, false);
}
if (cs == ISO_8859_1.INSTANCE) {
if (coder == LATIN1) {
return val;
}
return encode8859_1(coder, val, false);
}
if (cs == US_ASCII.INSTANCE) {
if (coder == LATIN1) {
if (isASCII(val)) {
return val;
} else {
throwUnmappable(val);
}
}
}
return encodeWithEncoder(cs, coder, val, false);
}
private static byte[] encodeASCII(byte coder, byte[] val) {
if (coder == LATIN1) {
int positives = StringCoding.countPositives(val, 0, val.length);
byte[] dst = val.clone();
if (positives < dst.length) {
replaceNegatives(dst, positives);
}
return dst;
}
int len = val.length >> 1;
byte[] dst = new byte[len];
int dp = 0;
for (int i = 0; i < len; i++) {
char c = StringUTF16.getChar(val, i);
if (c < 0x80) {
dst[dp++] = (byte)c;
continue;
}
if (Character.isHighSurrogate(c) && i + 1 < len &&
Character.isLowSurrogate(StringUTF16.getChar(val, i + 1))) {
i++;
}
dst[dp++] = '?';
}
if (len == dp) {
return dst;
}
return Arrays.copyOf(dst, dp);
}
private static void replaceNegatives(byte[] val, int fromIndex) {
for (int i = fromIndex; i < val.length; i++) {
if (val[i] < 0) {
val[i] = '?';
}
}
}
private static byte[] encode8859_1(byte coder, byte[] val) {
return encode8859_1(coder, val, true);
}
private static byte[] encode8859_1(byte coder, byte[] val, boolean doReplace) {
if (coder == LATIN1) {
return val.clone();
}
int len = val.length >> 1;
byte[] dst = new byte[len];
int dp = 0;
int sp = 0;
int sl = len;
while (sp < sl) {
int ret = StringCoding.implEncodeISOArray(val, sp, dst, dp, len);
sp = sp + ret;
dp = dp + ret;
if (ret != len) {
if (!doReplace) {
throwUnmappable(sp);
}
char c = StringUTF16.getChar(val, sp++);
if (Character.isHighSurrogate(c) && sp < sl &&
Character.isLowSurrogate(StringUTF16.getChar(val, sp))) {
sp++;
}
dst[dp++] = '?';
len = sl - sp;
}
}
if (dp == dst.length) {
return dst;
}
return Arrays.copyOf(dst, dp);
}
//------------------------------ utf8 ------------------------------------
/**
* Decodes ASCII from the source byte array into the destination
* char array. Used via JavaLangAccess from UTF_8 and other charset
* decoders.
*
* @return the number of bytes successfully decoded, at most len
*/
/* package-private */
static int decodeASCII(byte[] sa, int sp, char[] da, int dp, int len) {
int count = StringCoding.countPositives(sa, sp, len);
while (count < len) {
if (sa[sp + count] < 0) {
break;
}
count++;
}
StringLatin1.inflate(sa, sp, da, dp, count);
return count;
}
private static boolean isNotContinuation(int b) {
return (b & 0xc0) != 0x80;
}
private static boolean isMalformed3(int b1, int b2, int b3) {
return (b1 == (byte)0xe0 && (b2 & 0xe0) == 0x80) ||
(b2 & 0xc0) != 0x80 || (b3 & 0xc0) != 0x80;
}
private static boolean isMalformed3_2(int b1, int b2) {
return (b1 == (byte)0xe0 && (b2 & 0xe0) == 0x80) ||
(b2 & 0xc0) != 0x80;
}
private static boolean isMalformed4(int b2, int b3, int b4) {
return (b2 & 0xc0) != 0x80 || (b3 & 0xc0) != 0x80 ||
(b4 & 0xc0) != 0x80;
}
private static boolean isMalformed4_2(int b1, int b2) {
return (b1 == 0xf0 && (b2 < 0x90 || b2 > 0xbf)) ||
(b1 == 0xf4 && (b2 & 0xf0) != 0x80) ||
(b2 & 0xc0) != 0x80;
}
private static boolean isMalformed4_3(int b3) {
return (b3 & 0xc0) != 0x80;
}
private static char decode2(int b1, int b2) {
return (char)(((b1 << 6) ^ b2) ^
(((byte) 0xC0 << 6) ^
((byte) 0x80 << 0)));
}
private static char decode3(int b1, int b2, int b3) {
return (char)((b1 << 12) ^
(b2 << 6) ^
(b3 ^
(((byte) 0xE0 << 12) ^
((byte) 0x80 << 6) ^
((byte) 0x80 << 0))));
}
private static int decode4(int b1, int b2, int b3, int b4) {
return ((b1 << 18) ^
(b2 << 12) ^
(b3 << 6) ^
(b4 ^
(((byte) 0xF0 << 18) ^
((byte) 0x80 << 12) ^
((byte) 0x80 << 6) ^
((byte) 0x80 << 0))));
}
private static int decodeUTF8_UTF16(byte[] src, int sp, int sl, byte[] dst, int dp, boolean doReplace) {
while (sp < sl) {
int b1 = src[sp++];
if (b1 >= 0) {
StringUTF16.putChar(dst, dp++, (char) b1);
} else if ((b1 >> 5) == -2 && (b1 & 0x1e) != 0) {
if (sp < sl) {
int b2 = src[sp++];
if (isNotContinuation(b2)) {
if (!doReplace) {
throwMalformed(sp - 1, 1);
}
StringUTF16.putChar(dst, dp++, REPL);
sp--;
} else {
StringUTF16.putChar(dst, dp++, decode2(b1, b2));
}
continue;
}
if (!doReplace) {
throwMalformed(sp, 1); // underflow()
}
StringUTF16.putChar(dst, dp++, REPL);
break;
} else if ((b1 >> 4) == -2) {
if (sp + 1 < sl) {
int b2 = src[sp++];
int b3 = src[sp++];
if (isMalformed3(b1, b2, b3)) {
if (!doReplace) {
throwMalformed(sp - 3, 3);
}
StringUTF16.putChar(dst, dp++, REPL);
sp -= 3;
sp += malformed3(src, sp);
} else {
char c = decode3(b1, b2, b3);
if (Character.isSurrogate(c)) {
if (!doReplace) {
throwMalformed(sp - 3, 3);
}
StringUTF16.putChar(dst, dp++, REPL);
} else {
StringUTF16.putChar(dst, dp++, c);
}
}
continue;
}
if (sp < sl && isMalformed3_2(b1, src[sp])) {
if (!doReplace) {
throwMalformed(sp - 1, 2);
}
StringUTF16.putChar(dst, dp++, REPL);
continue;
}
if (!doReplace) {
throwMalformed(sp, 1);
}
StringUTF16.putChar(dst, dp++, REPL);
break;
} else if ((b1 >> 3) == -2) {
if (sp + 2 < sl) {
int b2 = src[sp++];
int b3 = src[sp++];
int b4 = src[sp++];
int uc = decode4(b1, b2, b3, b4);
if (isMalformed4(b2, b3, b4) ||
!Character.isSupplementaryCodePoint(uc)) { // shortest form check
if (!doReplace) {
throwMalformed(sp - 4, 4);
}
StringUTF16.putChar(dst, dp++, REPL);
sp -= 4;
sp += malformed4(src, sp);
} else {
StringUTF16.putChar(dst, dp++, Character.highSurrogate(uc));
StringUTF16.putChar(dst, dp++, Character.lowSurrogate(uc));
}
continue;
}
b1 &= 0xff;
if (b1 > 0xf4 || sp < sl && isMalformed4_2(b1, src[sp] & 0xff)) {
if (!doReplace) {
throwMalformed(sp - 1, 1); // or 2
}
StringUTF16.putChar(dst, dp++, REPL);
continue;
}
if (!doReplace) {
throwMalformed(sp - 1, 1);
}
sp++;
StringUTF16.putChar(dst, dp++, REPL);
if (sp < sl && isMalformed4_3(src[sp])) {
continue;
}
break;
} else {
if (!doReplace) {
throwMalformed(sp - 1, 1);
}
StringUTF16.putChar(dst, dp++, REPL);
}
}
return dp;
}
private static int decodeWithDecoder(CharsetDecoder cd, char[] dst, byte[] src, int offset, int length)
throws CharacterCodingException {
ByteBuffer bb = ByteBuffer.wrap(src, offset, length);
CharBuffer cb = CharBuffer.wrap(dst, 0, dst.length);
CoderResult cr = cd.decode(bb, cb, true);
if (!cr.isUnderflow())
cr.throwException();
cr = cd.flush(cb);
if (!cr.isUnderflow())
cr.throwException();
return cb.position();
}
private static int malformed3(byte[] src, int sp) {
int b1 = src[sp++];
int b2 = src[sp]; // no need to lookup b3
return ((b1 == (byte)0xe0 && (b2 & 0xe0) == 0x80) ||
isNotContinuation(b2)) ? 1 : 2;
}
private static int malformed4(byte[] src, int sp) {
// we don't care the speed here
int b1 = src[sp++] & 0xff;
int b2 = src[sp++] & 0xff;
if (b1 > 0xf4 ||
(b1 == 0xf0 && (b2 < 0x90 || b2 > 0xbf)) ||
(b1 == 0xf4 && (b2 & 0xf0) != 0x80) ||
isNotContinuation(b2))
return 1;
if (isNotContinuation(src[sp]))
return 2;
return 3;
}
private static void throwMalformed(int off, int nb) {
String msg = "malformed input off : " + off + ", length : " + nb;
throw new IllegalArgumentException(msg, new MalformedInputException(nb));
}
private static void throwMalformed(byte[] val) {
int dp = StringCoding.countPositives(val, 0, val.length);
throwMalformed(dp, 1);
}
private static void throwUnmappable(int off) {
String msg = "malformed input off : " + off + ", length : 1";
throw new IllegalArgumentException(msg, new UnmappableCharacterException(1));
}
private static void throwUnmappable(byte[] val) {
int dp = StringCoding.countPositives(val, 0, val.length);
throwUnmappable(dp);
}
private static byte[] encodeUTF8(byte coder, byte[] val, boolean doReplace) {
if (coder == UTF16) {
return encodeUTF8_UTF16(val, doReplace);
}
if (!StringCoding.hasNegatives(val, 0, val.length)) {
return val.clone();
}
int dp = 0;
byte[] dst = StringUTF16.newBytesFor(val.length);
for (byte c : val) {
if (c < 0) {
dst[dp++] = (byte) (0xc0 | ((c & 0xff) >> 6));
dst[dp++] = (byte) (0x80 | (c & 0x3f));
} else {
dst[dp++] = c;
}
}
if (dp == dst.length) {
return dst;
}
return Arrays.copyOf(dst, dp);
}
private static byte[] encodeUTF8_UTF16(byte[] val, boolean doReplace) {
int dp = 0;
int sp = 0;
int sl = val.length >> 1;
// UTF-8 encoded can be as much as 3 times the string length
// For very large estimate, (as in overflow of 32 bit int), precompute the exact size
long allocLen = (sl * 3 < 0) ? computeSizeUTF8_UTF16(val, doReplace) : sl * 3;
if (allocLen > (long)Integer.MAX_VALUE) {
throw new OutOfMemoryError("Required length exceeds implementation limit");
}
byte[] dst = new byte[(int) allocLen];
while (sp < sl) {
// ascii fast loop;
char c = StringUTF16.getChar(val, sp);
if (c >= '\u0080') {
break;
}
dst[dp++] = (byte)c;
sp++;
}
while (sp < sl) {
char c = StringUTF16.getChar(val, sp++);
if (c < 0x80) {
dst[dp++] = (byte)c;
} else if (c < 0x800) {
dst[dp++] = (byte)(0xc0 | (c >> 6));
dst[dp++] = (byte)(0x80 | (c & 0x3f));
} else if (Character.isSurrogate(c)) {
int uc = -1;
char c2;
if (Character.isHighSurrogate(c) && sp < sl &&
Character.isLowSurrogate(c2 = StringUTF16.getChar(val, sp))) {
uc = Character.toCodePoint(c, c2);
}
if (uc < 0) {
if (doReplace) {
dst[dp++] = '?';
} else {
throwUnmappable(sp - 1);
}
} else {
dst[dp++] = (byte)(0xf0 | ((uc >> 18)));
dst[dp++] = (byte)(0x80 | ((uc >> 12) & 0x3f));
dst[dp++] = (byte)(0x80 | ((uc >> 6) & 0x3f));
dst[dp++] = (byte)(0x80 | (uc & 0x3f));
sp++; // 2 chars
}
} else {
// 3 bytes, 16 bits
dst[dp++] = (byte)(0xe0 | ((c >> 12)));
dst[dp++] = (byte)(0x80 | ((c >> 6) & 0x3f));
dst[dp++] = (byte)(0x80 | (c & 0x3f));
}
}
if (dp == dst.length) {
return dst;
}
return Arrays.copyOf(dst, dp);
}
/**
* {@return the exact size required to UTF_8 encode this UTF16 string}
* @param val UTF16 encoded byte array
* @param doReplace true to replace unmappable characters
*/
private static long computeSizeUTF8_UTF16(byte[] val, boolean doReplace) {
long dp = 0L;
int sp = 0;
int sl = val.length >> 1;
while (sp < sl) {
char c = StringUTF16.getChar(val, sp++);
if (c < 0x80) {
dp++;
} else if (c < 0x800) {
dp += 2;
} else if (Character.isSurrogate(c)) {
int uc = -1;
char c2;
if (Character.isHighSurrogate(c) && sp < sl &&
Character.isLowSurrogate(c2 = StringUTF16.getChar(val, sp))) {
uc = Character.toCodePoint(c, c2);
}
if (uc < 0) {
if (doReplace) {
dp++;
} else {
throwUnmappable(sp - 1);
}
} else {
dp += 4;
sp++; // 2 chars
}
} else {
// 3 bytes, 16 bits
dp += 3;
}
}
return dp;
}
/**
* Constructs a new {@code String} by decoding the specified array of bytes
* using the specified {@linkplain java.nio.charset.Charset charset}. The
* length of the new {@code String} is a function of the charset, and hence
* may not be equal to the length of the byte array.
*
* <p> The behavior of this constructor when the given bytes are not valid
* in the given charset is unspecified. The {@link
* java.nio.charset.CharsetDecoder} class should be used when more control
* over the decoding process is required.
*
* <p> The contents of the string are unspecified if the byte array
* is modified during string construction.
*
* @param bytes
* The bytes to be decoded into characters
*
* @param charsetName
* The name of a supported {@linkplain java.nio.charset.Charset
* charset}
*
* @throws UnsupportedEncodingException
* If the named charset is not supported
*
* @since 1.1
*/
public String(byte[] bytes, String charsetName)
throws UnsupportedEncodingException {
this(lookupCharset(charsetName), bytes, 0, bytes.length);
}
/**
* Constructs a new {@code String} by decoding the specified array of
* bytes using the specified {@linkplain java.nio.charset.Charset charset}.
* The length of the new {@code String} is a function of the charset, and
* hence may not be equal to the length of the byte array.
*
* <p> This method always replaces malformed-input and unmappable-character
* sequences with this charset's default replacement string. The {@link
* java.nio.charset.CharsetDecoder} class should be used when more control
* over the decoding process is required.
*
* <p> The contents of the string are unspecified if the byte array
* is modified during string construction.
*
* @param bytes
* The bytes to be decoded into characters
*
* @param charset
* The {@linkplain java.nio.charset.Charset charset} to be used to
* decode the {@code bytes}
*
* @since 1.6
*/
public String(byte[] bytes, Charset charset) {
this(Objects.requireNonNull(charset), bytes, 0, bytes.length);
}
/**
* Constructs a new {@code String} by decoding the specified subarray of
* bytes using the {@link Charset#defaultCharset() default charset}.
* The length of the new {@code String} is a function of the charset,
* and hence may not be equal to the length of the subarray.
*
* <p> The behavior of this constructor when the given bytes are not valid
* in the default charset is unspecified. The {@link
* java.nio.charset.CharsetDecoder} class should be used when more control
* over the decoding process is required.
*
* <p> The contents of the string are unspecified if the byte array
* is modified during string construction.
*
* @param bytes
* The bytes to be decoded into characters
*
* @param offset
* The index of the first byte to decode
*
* @param length
* The number of bytes to decode
*
* @throws IndexOutOfBoundsException
* If {@code offset} is negative, {@code length} is negative, or
* {@code offset} is greater than {@code bytes.length - length}
*
* @since 1.1
*/
public String(byte[] bytes, int offset, int length) {
this(Charset.defaultCharset(), bytes, checkBoundsOffCount(offset, length, bytes.length), length);
}
/**
* Constructs a new {@code String} by decoding the specified array of bytes
* using the {@link Charset#defaultCharset() default charset}. The length
* of the new {@code String} is a function of the charset, and hence may not
* be equal to the length of the byte array.
*
* <p> The behavior of this constructor when the given bytes are not valid
* in the default charset is unspecified. The {@link
* java.nio.charset.CharsetDecoder} class should be used when more control
* over the decoding process is required.
*
* <p> The contents of the string are unspecified if the byte array
* is modified during string construction.
*
* @param bytes
* The bytes to be decoded into characters
*
* @since 1.1
*/
public String(byte[] bytes) {
this(Charset.defaultCharset(), bytes, 0, bytes.length);
}
/**
* Allocates a new string that contains the sequence of characters
* currently contained in the string buffer argument. The contents of the
* string buffer are copied; subsequent modification of the string buffer
* does not affect the newly created string.
*
* @param buffer
* A {@code StringBuffer}
*/
public String(StringBuffer buffer) {
this(buffer.toString());
}
/**
* Allocates a new string that contains the sequence of characters
* currently contained in the string builder argument. The contents of the
* string builder are copied; subsequent modification of the string builder
* does not affect the newly created string.
*
* <p> The contents of the string are unspecified if the {@code StringBuilder}
* is modified during string construction.
*
* <p> This constructor is provided to ease migration to {@code
* StringBuilder}. Obtaining a string from a string builder via the {@code
* toString} method is likely to run faster and is generally preferred.
*
* @param builder
* A {@code StringBuilder}
*
* @since 1.5
*/
public String(StringBuilder builder) {
this(builder, null);
}
/**
* Returns the length of this string.
* The length is equal to the number of <a href="Character.html#unicode">Unicode
* code units</a> in the string.
*
* @return the length of the sequence of characters represented by this
* object.
*/
public int length() {
return value.length >> coder();
}
/**
* Returns {@code true} if, and only if, {@link #length()} is {@code 0}.
*
* @return {@code true} if {@link #length()} is {@code 0}, otherwise
* {@code false}
*
* @apiNote
* To determine whether a string contains only
* {@linkplain Character#isWhitespace(int) white space}, use
* {@link #isBlank() isBlank}.
*
* @since 1.6
*/
@Override
public boolean isEmpty() {
return value.length == 0;
}
/**
* Returns the {@code char} value at the
* specified index. An index ranges from {@code 0} to
* {@code length() - 1}. The first {@code char} value of the sequence
* is at index {@code 0}, the next at index {@code 1},
* and so on, as for array indexing.
*
* <p>If the {@code char} value specified by the index is a
* <a href="Character.html#unicode">surrogate</a>, the surrogate
* value is returned.
*
* @param index the index of the {@code char} value.
* @return the {@code char} value at the specified index of this string.
* The first {@code char} value is at index {@code 0}.
* @throws IndexOutOfBoundsException if the {@code index}
* argument is negative or not less than the length of this
* string.
*/
public char charAt(int index) {
if (isLatin1()) {
return StringLatin1.charAt(value, index);
} else {
return StringUTF16.charAt(value, index);
}
}
/**
* Returns the character (Unicode code point) at the specified
* index. The index refers to {@code char} values
* (Unicode code units) and ranges from {@code 0} to
* {@link #length()}{@code - 1}.
*
* <p> If the {@code char} value specified at the given index
* is in the high-surrogate range, the following index is less
* than the length of this {@code String}, and the
* {@code char} value at the following index is in the
* low-surrogate range, then the supplementary code point
* corresponding to this surrogate pair is returned. Otherwise,
* the {@code char} value at the given index is returned.
*
* @param index the index to the {@code char} values
* @return the code point value of the character at the
* {@code index}
* @throws IndexOutOfBoundsException if the {@code index}
* argument is negative or not less than the length of this
* string.
* @since 1.5
*/
public int codePointAt(int index) {
if (isLatin1()) {
checkIndex(index, value.length);
return value[index] & 0xff;
}
int length = value.length >> 1;
checkIndex(index, length);
return StringUTF16.codePointAt(value, index, length);
}
/**
* Returns the character (Unicode code point) before the specified
* index. The index refers to {@code char} values
* (Unicode code units) and ranges from {@code 1} to {@link
* CharSequence#length() length}.
*
* <p> If the {@code char} value at {@code (index - 1)}
* is in the low-surrogate range, {@code (index - 2)} is not
* negative, and the {@code char} value at {@code (index -
* 2)} is in the high-surrogate range, then the
* supplementary code point value of the surrogate pair is
* returned. If the {@code char} value at {@code index -
* 1} is an unpaired low-surrogate or a high-surrogate, the
* surrogate value is returned.
*
* @param index the index following the code point that should be returned
* @return the Unicode code point value before the given index.
* @throws IndexOutOfBoundsException if the {@code index}
* argument is less than 1 or greater than the length
* of this string.
* @since 1.5
*/
public int codePointBefore(int index) {
int i = index - 1;
checkIndex(i, length());
if (isLatin1()) {
return (value[i] & 0xff);
}
return StringUTF16.codePointBefore(value, index);
}
/**
* Returns the number of Unicode code points in the specified text
* range of this {@code String}. The text range begins at the
* specified {@code beginIndex} and extends to the
* {@code char} at index {@code endIndex - 1}. Thus the
* length (in {@code char}s) of the text range is
* {@code endIndex-beginIndex}. Unpaired surrogates within
* the text range count as one code point each.
*
* @param beginIndex the index to the first {@code char} of
* the text range.
* @param endIndex the index after the last {@code char} of
* the text range.
* @return the number of Unicode code points in the specified text
* range
* @throws IndexOutOfBoundsException if the
* {@code beginIndex} is negative, or {@code endIndex}
* is larger than the length of this {@code String}, or
* {@code beginIndex} is larger than {@code endIndex}.
* @since 1.5
*/
public int codePointCount(int beginIndex, int endIndex) {
Objects.checkFromToIndex(beginIndex, endIndex, length());
if (isLatin1()) {
return endIndex - beginIndex;
}
return StringUTF16.codePointCount(value, beginIndex, endIndex);
}
/**
* Returns the index within this {@code String} that is
* offset from the given {@code index} by
* {@code codePointOffset} code points. Unpaired surrogates
* within the text range given by {@code index} and
* {@code codePointOffset} count as one code point each.
*
* @param index the index to be offset
* @param codePointOffset the offset in code points
* @return the index within this {@code String}
* @throws IndexOutOfBoundsException if {@code index}
* is negative or larger than the length of this
* {@code String}, or if {@code codePointOffset} is positive
* and the substring starting with {@code index} has fewer
* than {@code codePointOffset} code points,
* or if {@code codePointOffset} is negative and the substring
* before {@code index} has fewer than the absolute value
* of {@code codePointOffset} code points.
* @since 1.5
*/
public int offsetByCodePoints(int index, int codePointOffset) {
return Character.offsetByCodePoints(this, index, codePointOffset);
}
/**
* {@inheritDoc CharSequence}
* @param srcBegin {@inheritDoc CharSequence}
* @param srcEnd {@inheritDoc CharSequence}
* @param dst {@inheritDoc CharSequence}
* @param dstBegin {@inheritDoc CharSequence}
* @throws IndexOutOfBoundsException {@inheritDoc CharSequence}
*/
@Override
public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) {
checkBoundsBeginEnd(srcBegin, srcEnd, length());
checkBoundsOffCount(dstBegin, srcEnd - srcBegin, dst.length);
if (isLatin1()) {
StringLatin1.getChars(value, srcBegin, srcEnd, dst, dstBegin);
} else {
StringUTF16.getChars(value, srcBegin, srcEnd, dst, dstBegin);
}
}
/**
* Copies characters from this string into the destination byte array. Each
* byte receives the 8 low-order bits of the corresponding character. The
* eight high-order bits of each character are not copied and do not
* participate in the transfer in any way.
*
* <p> The first character to be copied is at index {@code srcBegin}; the
* last character to be copied is at index {@code srcEnd-1}. The total
* number of characters to be copied is {@code srcEnd-srcBegin}. The
* characters, converted to bytes, are copied into the subarray of {@code
* dst} starting at index {@code dstBegin} and ending at index:
*
* <blockquote><pre>
* dstBegin + (srcEnd-srcBegin) - 1
* </pre></blockquote>
*
* @deprecated This method does not properly convert characters into
* bytes. As of JDK&nbsp;1.1, the preferred way to do this is via the
* {@link #getBytes()} method, which uses the {@link Charset#defaultCharset()
* default charset}.
*
* @param srcBegin
* Index of the first character in the string to copy
*
* @param srcEnd
* Index after the last character in the string to copy
*
* @param dst
* The destination array
*
* @param dstBegin
* The start offset in the destination array
*
* @throws IndexOutOfBoundsException
* If any of the following is true:
* <ul>
* <li> {@code srcBegin} is negative
* <li> {@code srcBegin} is greater than {@code srcEnd}
* <li> {@code srcEnd} is greater than the length of this String
* <li> {@code dstBegin} is negative
* <li> {@code dstBegin+(srcEnd-srcBegin)} is larger than {@code
* dst.length}
* </ul>
*/
@Deprecated(since="1.1")
public void getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin) {
checkBoundsBeginEnd(srcBegin, srcEnd, length());
Objects.requireNonNull(dst);
checkBoundsOffCount(dstBegin, srcEnd - srcBegin, dst.length);
if (isLatin1()) {
StringLatin1.getBytes(value, srcBegin, srcEnd, dst, dstBegin);
} else {
StringUTF16.getBytes(value, srcBegin, srcEnd, dst, dstBegin);
}
}
/**
* Encodes this {@code String} into a sequence of bytes using the named
* charset, storing the result into a new byte array.
*
* <p> The behavior of this method when this string cannot be encoded in
* the given charset is unspecified. The {@link
* java.nio.charset.CharsetEncoder} class should be used when more control
* over the encoding process is required.
*
* @param charsetName
* The name of a supported {@linkplain java.nio.charset.Charset
* charset}
*
* @return The resultant byte array
*
* @throws UnsupportedEncodingException
* If the named charset is not supported
*
* @since 1.1
*/
public byte[] getBytes(String charsetName)
throws UnsupportedEncodingException {
return encode(lookupCharset(charsetName), coder(), value);
}
/**
* Encodes this {@code String} into a sequence of bytes using the given
* {@linkplain java.nio.charset.Charset charset}, storing the result into a
* new byte array.
*
* <p> This method always replaces malformed-input and unmappable-character
* sequences with this charset's default replacement byte array. The
* {@link java.nio.charset.CharsetEncoder} class should be used when more
* control over the encoding process is required.
*
* @param charset
* The {@linkplain java.nio.charset.Charset} to be used to encode
* the {@code String}
*
* @return The resultant byte array
*
* @since 1.6
*/
public byte[] getBytes(Charset charset) {
if (charset == null) throw new NullPointerException();
return encode(charset, coder(), value);
}
/**
* Encodes this {@code String} into a sequence of bytes using the
* {@link Charset#defaultCharset() default charset}, storing the result
* into a new byte array.
*
* <p> The behavior of this method when this string cannot be encoded in
* the default charset is unspecified. The {@link
* java.nio.charset.CharsetEncoder} class should be used when more control
* over the encoding process is required.
*
* @return The resultant byte array
*
* @since 1.1
*/
public byte[] getBytes() {
return encode(Charset.defaultCharset(), coder(), value);
}
boolean bytesCompatible(Charset charset) {
if (isLatin1()) {
if (charset == ISO_8859_1.INSTANCE) {
return true; // ok, same encoding
} else if (charset == UTF_8.INSTANCE || charset == US_ASCII.INSTANCE) {
return !StringCoding.hasNegatives(value, 0, value.length); // ok, if ASCII-compatible
}
}
return false;
}
void copyToSegmentRaw(MemorySegment segment, long offset) {
MemorySegment.copy(value, 0, segment, ValueLayout.JAVA_BYTE, offset, value.length);
}
/**
* Compares this string to the specified object. The result is {@code
* true} if and only if the argument is not {@code null} and is a {@code
* String} object that represents the same sequence of characters as this
* object.
*
* <p>For finer-grained String comparison, refer to
* {@link java.text.Collator}.
*
* @param anObject
* The object to compare this {@code String} against
*
* @return {@code true} if the given object represents a {@code String}
* equivalent to this string, {@code false} otherwise
*
* @see #compareTo(String)
* @see #equalsIgnoreCase(String)
*/
public boolean equals(Object anObject) {
if (this == anObject) {
return true;
}
return (anObject instanceof String aString)
&& (!COMPACT_STRINGS || this.coder == aString.coder)
&& StringLatin1.equals(value, aString.value);
}
/**
* Compares this string to the specified {@code StringBuffer}. The result
* is {@code true} if and only if this {@code String} represents the same
* sequence of characters as the specified {@code StringBuffer}. This method
* synchronizes on the {@code StringBuffer}.
*
* <p>For finer-grained String comparison, refer to
* {@link java.text.Collator}.
*
* @param sb
* The {@code StringBuffer} to compare this {@code String} against
*
* @return {@code true} if this {@code String} represents the same
* sequence of characters as the specified {@code StringBuffer},
* {@code false} otherwise
*
* @since 1.4
*/
public boolean contentEquals(StringBuffer sb) {
return contentEquals((CharSequence)sb);
}
private boolean nonSyncContentEquals(AbstractStringBuilder sb) {
int len = length();
if (len != sb.length()) {
return false;
}
byte[] v1 = value;
byte[] v2 = sb.getValue();
byte coder = coder();
if (coder == sb.getCoder()) {
return v1.length <= v2.length && ArraysSupport.mismatch(v1, v2, v1.length) < 0;
} else {
if (coder != LATIN1) { // utf16 str and latin1 abs can never be "equal"
return false;
}
return StringUTF16.contentEquals(v1, v2, len);
}
}
/**
* Compares this string to the specified {@code CharSequence}. The
* result is {@code true} if and only if this {@code String} represents the
* same sequence of char values as the specified sequence. Note that if the
* {@code CharSequence} is a {@code StringBuffer} then the method
* synchronizes on it.
*
* <p>For finer-grained String comparison, refer to
* {@link java.text.Collator}.
*
* @param cs
* The sequence to compare this {@code String} against
*
* @return {@code true} if this {@code String} represents the same
* sequence of char values as the specified sequence, {@code
* false} otherwise
*
* @since 1.5
*/
public boolean contentEquals(CharSequence cs) {
// Argument is a StringBuffer, StringBuilder
if (cs instanceof AbstractStringBuilder) {
if (cs instanceof StringBuffer) {
synchronized(cs) {
return nonSyncContentEquals((AbstractStringBuilder)cs);
}
} else {
return nonSyncContentEquals((AbstractStringBuilder)cs);
}
}
// Argument is a String
if (cs instanceof String) {
return equals(cs);
}
// Argument is a generic CharSequence
int n = cs.length();
if (n != length()) {
return false;
}
byte[] val = this.value;
if (isLatin1()) {
for (int i = 0; i < n; i++) {
if ((val[i] & 0xff) != cs.charAt(i)) {
return false;
}
}
} else {
if (!StringUTF16.contentEquals(val, cs, n)) {
return false;
}
}
return true;
}
/**
* Compares this {@code String} to another {@code String}, ignoring case
* considerations. Two strings are considered equal ignoring case if they
* are of the same length and corresponding Unicode code points in the two
* strings are equal ignoring case.
*
* <p> Two Unicode code points are considered the same
* ignoring case if at least one of the following is true:
* <ul>
* <li> The two Unicode code points are the same (as compared by the
* {@code ==} operator)
* <li> Calling {@code Character.toLowerCase(Character.toUpperCase(int))}
* on each Unicode code point produces the same result
* </ul>
*
* <p>Note that this method does <em>not</em> take locale into account, and
* will result in unsatisfactory results for certain locales. The
* {@link java.text.Collator} class provides locale-sensitive comparison.
*
* @param anotherString
* The {@code String} to compare this {@code String} against
*
* @return {@code true} if the argument is not {@code null} and it
* represents an equivalent {@code String} ignoring case; {@code
* false} otherwise
*
* @see #equals(Object)
* @see #codePoints()
*/
public boolean equalsIgnoreCase(String anotherString) {
return (this == anotherString) ? true
: (anotherString != null)
&& (anotherString.length() == length())
&& regionMatches(true, 0, anotherString, 0, length());
}
/**
* Compares two strings lexicographically.
* The comparison is based on the Unicode value of each character in
* the strings. The character sequence represented by this
* {@code String} object is compared lexicographically to the
* character sequence represented by the argument string. The result is
* a negative integer if this {@code String} object
* lexicographically precedes the argument string. The result is a
* positive integer if this {@code String} object lexicographically
* follows the argument string. The result is zero if the strings
* are equal; {@code compareTo} returns {@code 0} exactly when
* the {@link #equals(Object)} method would return {@code true}.
* <p>
* This is the definition of lexicographic ordering. If two strings are
* different, then either they have different characters at some index
* that is a valid index for both strings, or their lengths are different,
* or both. If they have different characters at one or more index
* positions, let <i>k</i> be the smallest such index; then the string
* whose character at position <i>k</i> has the smaller value, as
* determined by using the {@code <} operator, lexicographically precedes the
* other string. In this case, {@code compareTo} returns the
* difference of the two character values at position {@code k} in
* the two string -- that is, the value:
* <blockquote><pre>
* this.charAt(k)-anotherString.charAt(k)
* </pre></blockquote>
* If there is no index position at which they differ, then the shorter
* string lexicographically precedes the longer string. In this case,
* {@code compareTo} returns the difference of the lengths of the
* strings -- that is, the value:
* <blockquote><pre>
* this.length()-anotherString.length()
* </pre></blockquote>
*
* <p>For finer-grained String comparison, refer to
* {@link java.text.Collator}.
*
* @param anotherString the {@code String} to be compared.
* @return the value {@code 0} if the argument string is equal to
* this string; a value less than {@code 0} if this string
* is lexicographically less than the string argument; and a
* value greater than {@code 0} if this string is
* lexicographically greater than the string argument.
*/
public int compareTo(String anotherString) {
byte[] v1 = value;
byte[] v2 = anotherString.value;
byte coder = coder();
if (coder == anotherString.coder()) {
return coder == LATIN1 ? StringLatin1.compareTo(v1, v2)
: StringUTF16.compareTo(v1, v2);
}
return coder == LATIN1 ? StringLatin1.compareToUTF16(v1, v2)
: StringUTF16.compareToLatin1(v1, v2);
}
/**
* A Comparator that orders {@code String} objects as by
* {@link #compareToIgnoreCase(String) compareToIgnoreCase}.
* This comparator is serializable.
* <p>
* Note that this Comparator does <em>not</em> take locale into account,
* and will result in an unsatisfactory ordering for certain locales.
* The {@link java.text.Collator} class provides locale-sensitive comparison.
*
* @see java.text.Collator
* @since 1.2
*/
public static final Comparator<String> CASE_INSENSITIVE_ORDER
= new CaseInsensitiveComparator();
/**
* CaseInsensitiveComparator for Strings.
*/
private static class CaseInsensitiveComparator
implements Comparator<String>, java.io.Serializable {
// use serialVersionUID from JDK 1.2.2 for interoperability
@java.io.Serial
private static final long serialVersionUID = 8575799808933029326L;
public int compare(String s1, String s2) {
byte[] v1 = s1.value;
byte[] v2 = s2.value;
byte coder = s1.coder();
if (coder == s2.coder()) {
return coder == LATIN1 ? StringLatin1.compareToCI(v1, v2)
: StringUTF16.compareToCI(v1, v2);
}
return coder == LATIN1 ? StringLatin1.compareToCI_UTF16(v1, v2)
: StringUTF16.compareToCI_Latin1(v1, v2);
}
/** Replaces the de-serialized object. */
@java.io.Serial
private Object readResolve() { return CASE_INSENSITIVE_ORDER; }
}
/**
* Compares two strings lexicographically, ignoring case
* differences. This method returns an integer whose sign is that of
* calling {@code compareTo} with case folded versions of the strings
* where case differences have been eliminated by calling
* {@code Character.toLowerCase(Character.toUpperCase(int))} on
* each Unicode code point.
* <p>
* Note that this method does <em>not</em> take locale into account,
* and will result in an unsatisfactory ordering for certain locales.
* The {@link java.text.Collator} class provides locale-sensitive comparison.
*
* @param str the {@code String} to be compared.
* @return a negative integer, zero, or a positive integer as the
* specified String is greater than, equal to, or less
* than this String, ignoring case considerations.
* @see java.text.Collator
* @see #codePoints()
* @since 1.2
*/
public int compareToIgnoreCase(String str) {
return CASE_INSENSITIVE_ORDER.compare(this, str);
}
/**
* Tests if two string regions are equal.
* <p>
* A substring of this {@code String} object is compared to a substring
* of the argument other. The result is true if these substrings
* represent identical character sequences. The substring of this
* {@code String} object to be compared begins at index {@code toffset}
* and has length {@code len}. The substring of other to be compared
* begins at index {@code ooffset} and has length {@code len}. The
* result is {@code false} if and only if at least one of the following
* is true:
* <ul><li>{@code toffset} is negative.
* <li>{@code ooffset} is negative.
* <li>{@code toffset+len} is greater than the length of this
* {@code String} object.
* <li>{@code ooffset+len} is greater than the length of the other
* argument.
* <li>There is some nonnegative integer <i>k</i> less than {@code len}
* such that:
* {@code this.charAt(toffset + }<i>k</i>{@code ) != other.charAt(ooffset + }
* <i>k</i>{@code )}
* </ul>
*
* <p>Note that this method does <em>not</em> take locale into account. The
* {@link java.text.Collator} class provides locale-sensitive comparison.
*
* @param toffset the starting offset of the subregion in this string.
* @param other the string argument.
* @param ooffset the starting offset of the subregion in the string
* argument.
* @param len the number of characters to compare.
* @return {@code true} if the specified subregion of this string
* exactly matches the specified subregion of the string argument;
* {@code false} otherwise.
*/
public boolean regionMatches(int toffset, String other, int ooffset, int len) {
// Note: toffset, ooffset, or len might be near -1>>>1.
if ((ooffset < 0) || (toffset < 0) ||
(toffset > (long)length() - len) ||
(ooffset > (long)other.length() - len)) {
return false;
}
// Any strings match if len <= 0
if (len <= 0) {
return true;
}
byte[] tv = value;
byte[] ov = other.value;
byte coder = coder();
if (coder == other.coder()) {
if (coder == UTF16) {
toffset <<= UTF16;
ooffset <<= UTF16;
len <<= UTF16;
}
return ArraysSupport.mismatch(tv, toffset,
ov, ooffset, len) < 0;
} else {
if (coder == LATIN1) {
while (len-- > 0) {
if (StringLatin1.getChar(tv, toffset++) !=
StringUTF16.getChar(ov, ooffset++)) {
return false;
}
}
} else {
while (len-- > 0) {
if (StringUTF16.getChar(tv, toffset++) !=
StringLatin1.getChar(ov, ooffset++)) {
return false;
}
}
}
}
return true;
}
/**
* Tests if two string regions are equal.
* <p>
* A substring of this {@code String} object is compared to a substring
* of the argument {@code other}. The result is {@code true} if these
* substrings represent Unicode code point sequences that are the same,
* ignoring case if and only if {@code ignoreCase} is true.
* The sequences {@code tsequence} and {@code osequence} are compared,
* where {@code tsequence} is the sequence produced as if by calling
* {@code this.substring(toffset, toffset + len).codePoints()} and
* {@code osequence} is the sequence produced as if by calling
* {@code other.substring(ooffset, ooffset + len).codePoints()}.
* The result is {@code true} if and only if all of the following
* are true:
* <ul><li>{@code toffset} is non-negative.
* <li>{@code ooffset} is non-negative.
* <li>{@code toffset+len} is less than or equal to the length of this
* {@code String} object.
* <li>{@code ooffset+len} is less than or equal to the length of the other
* argument.
* <li>if {@code ignoreCase} is {@code false}, all pairs of corresponding Unicode
* code points are equal integer values; or if {@code ignoreCase} is {@code true},
* {@link Character#toLowerCase(int) Character.toLowerCase(}
* {@link Character#toUpperCase(int)}{@code )} on all pairs of Unicode code points
* results in equal integer values.
* </ul>
*
* <p>Note that this method does <em>not</em> take locale into account,
* and will result in unsatisfactory results for certain locales when
* {@code ignoreCase} is {@code true}. The {@link java.text.Collator} class
* provides locale-sensitive comparison.
*
* @param ignoreCase if {@code true}, ignore case when comparing
* characters.
* @param toffset the starting offset of the subregion in this
* string.
* @param other the string argument.
* @param ooffset the starting offset of the subregion in the string
* argument.
* @param len the number of characters (Unicode code units -
* 16bit {@code char} value) to compare.
* @return {@code true} if the specified subregion of this string
* matches the specified subregion of the string argument;
* {@code false} otherwise. Whether the matching is exact
* or case insensitive depends on the {@code ignoreCase}
* argument.
* @see #codePoints()
*/
public boolean regionMatches(boolean ignoreCase, int toffset,
String other, int ooffset, int len) {
if (!ignoreCase) {
return regionMatches(toffset, other, ooffset, len);
}
// Note: toffset, ooffset, or len might be near -1>>>1.
if ((ooffset < 0) || (toffset < 0)
|| (toffset > (long)length() - len)
|| (ooffset > (long)other.length() - len)) {
return false;
}
byte[] tv = value;
byte[] ov = other.value;
byte coder = coder();
if (coder == other.coder()) {
return coder == LATIN1
? StringLatin1.regionMatchesCI(tv, toffset, ov, ooffset, len)
: StringUTF16.regionMatchesCI(tv, toffset, ov, ooffset, len);
}
return coder == LATIN1
? StringLatin1.regionMatchesCI_UTF16(tv, toffset, ov, ooffset, len)
: StringUTF16.regionMatchesCI_Latin1(tv, toffset, ov, ooffset, len);
}
/**
* Tests if the substring of this string beginning at the
* specified index starts with the specified prefix.
*
* @param prefix the prefix.
* @param toffset where to begin looking in this string.
* @return {@code true} if the character sequence represented by the
* argument is a prefix of the substring of this object starting
* at index {@code toffset}; {@code false} otherwise.
* The result is {@code false} if {@code toffset} is
* negative or greater than the length of this
* {@code String} object; otherwise the result is the same
* as the result of the expression
* <pre>
* this.substring(toffset).startsWith(prefix)
* </pre>
*/
public boolean startsWith(String prefix, int toffset) {
// Note: toffset might be near -1>>>1.
if (toffset < 0 || toffset > length() - prefix.length()) {
return false;
}
byte[] ta = value;
byte[] pa = prefix.value;
int po = 0;
int pc = pa.length;
byte coder = coder();
if (coder == prefix.coder()) {
if (coder == UTF16) {
toffset <<= UTF16;
}
return ArraysSupport.mismatch(ta, toffset,
pa, 0, pc) < 0;
} else {
if (coder == LATIN1) { // && pcoder == UTF16
return false;
}
// coder == UTF16 && pcoder == LATIN1)
while (po < pc) {
if (StringUTF16.getChar(ta, toffset++) != (pa[po++] & 0xff)) {
return false;
}
}
}
return true;
}
/**
* Tests if this string starts with the specified prefix.
*
* @param prefix the prefix.
* @return {@code true} if the character sequence represented by the
* argument is a prefix of the character sequence represented by
* this string; {@code false} otherwise.
* Note also that {@code true} will be returned if the
* argument is an empty string or is equal to this
* {@code String} object as determined by the
* {@link #equals(Object)} method.
* @since 1.0
*/
public boolean startsWith(String prefix) {
return startsWith(prefix, 0);
}
/**
* Tests if this string ends with the specified suffix.
*
* @param suffix the suffix.
* @return {@code true} if the character sequence represented by the
* argument is a suffix of the character sequence represented by
* this object; {@code false} otherwise. Note that the
* result will be {@code true} if the argument is the
* empty string or is equal to this {@code String} object
* as determined by the {@link #equals(Object)} method.
*/
public boolean endsWith(String suffix) {
return startsWith(suffix, length() - suffix.length());
}
/**
* Returns a hash code for this string. The hash code for a
* {@code String} object is computed as
* <blockquote><pre>
* s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
* </pre></blockquote>
* using {@code int} arithmetic, where {@code s[i]} is the
* <i>i</i>th character of the string, {@code n} is the length of
* the string, and {@code ^} indicates exponentiation.
* (The hash value of the empty string is zero.)
*
* @return a hash code value for this object.
*/
public int hashCode() {
// The hash or hashIsZero fields are subject to a benign data race,
// making it crucial to ensure that any observable result of the
// calculation in this method stays correct under any possible read of
// these fields. Necessary restrictions to allow this to be correct
// without explicit memory fences or similar concurrency primitives is
// that we can ever only write to one of these two fields for a given
// String instance, and that the computation is idempotent and derived
// from immutable state
int h = hash;
if (h == 0 && !hashIsZero) {
h = isLatin1() ? StringLatin1.hashCode(value)
: StringUTF16.hashCode(value);
if (h == 0) {
hashIsZero = true;
} else {
hash = h;
}
}
return h;
}
/**
* Returns the index within this string of the first occurrence of
* the specified character. If a character with value
* {@code ch} occurs in the character sequence represented by
* this {@code String} object, then the index (in Unicode
* code units) of the first such occurrence is returned. For
* values of {@code ch} in the range from 0 to 0xFFFF
* (inclusive), this is the smallest value <i>k</i> such that:
* <blockquote><pre>
* this.charAt(<i>k</i>) == ch
* </pre></blockquote>
* is true. For other values of {@code ch}, it is the
* smallest value <i>k</i> such that:
* <blockquote><pre>
* this.codePointAt(<i>k</i>) == ch
* </pre></blockquote>
* is true. In either case, if no such character occurs in this
* string, then {@code -1} is returned.
*
* @param ch a character (Unicode code point).
* @return the index of the first occurrence of the character in the
* character sequence represented by this object, or
* {@code -1} if the character does not occur.
*/
public int indexOf(int ch) {
return isLatin1() ? StringLatin1.indexOf(value, ch, 0, value.length)
: StringUTF16.indexOf(value, ch, 0, value.length >> 1);
}
/**
* Returns the index within this string of the first occurrence of the
* specified character, starting the search at the specified index.
* <p>
* If a character with value {@code ch} occurs in the
* character sequence represented by this {@code String}
* object at an index no smaller than {@code fromIndex}, then
* the index of the first such occurrence is returned. For values
* of {@code ch} in the range from 0 to 0xFFFF (inclusive),
* this is the smallest value <i>k</i> such that:
* <blockquote><pre>
* (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> &gt;= fromIndex)
* </pre></blockquote>
* is true. For other values of {@code ch}, it is the
* smallest value <i>k</i> such that:
* <blockquote><pre>
* (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> &gt;= fromIndex)
* </pre></blockquote>
* is true. In either case, if no such character occurs in this
* string at or after position {@code fromIndex}, then
* {@code -1} is returned.
*
* <p>
* There is no restriction on the value of {@code fromIndex}. If it
* is negative, it has the same effect as if it were zero: this entire
* string may be searched. If it is greater than the length of this
* string, it has the same effect as if it were equal to the length of
* this string: {@code -1} is returned.
*
* <p>All indices are specified in {@code char} values
* (Unicode code units).
*
* @param ch a character (Unicode code point).
* @param fromIndex the index to start the search from.
* @return the index of the first occurrence of the character in the
* character sequence represented by this object that is greater
* than or equal to {@code fromIndex}, or {@code -1}
* if the character does not occur.
*
* @apiNote
* Unlike {@link #substring(int)}, for example, this method does not throw
* an exception when {@code fromIndex} is outside the valid range.
* Rather, it returns -1 when {@code fromIndex} is larger than the length of
* the string.
* This result is, by itself, indistinguishable from a genuine absence of
* {@code ch} in the string.
* If stricter behavior is needed, {@link #indexOf(int, int, int)}
* should be considered instead.
* On a {@link String} {@code s}, for example,
* {@code s.indexOf(ch, fromIndex, s.length())} would throw if
* {@code fromIndex} were larger than the string length, or were negative.
*/
public int indexOf(int ch, int fromIndex) {
fromIndex = Math.max(fromIndex, 0);
return isLatin1() ? StringLatin1.indexOf(value, ch, Math.min(fromIndex, value.length), value.length)
: StringUTF16.indexOf(value, ch, Math.min(fromIndex, value.length >> 1), value.length >> 1);
}
/**
* Returns the index within this string of the first occurrence of the
* specified character, starting the search at {@code beginIndex} and
* stopping before {@code endIndex}.
*
* <p>If a character with value {@code ch} occurs in the
* character sequence represented by this {@code String}
* object at an index no smaller than {@code beginIndex} but smaller than
* {@code endIndex}, then
* the index of the first such occurrence is returned. For values
* of {@code ch} in the range from 0 to 0xFFFF (inclusive),
* this is the smallest value <i>k</i> such that:
* <blockquote><pre>
* (this.charAt(<i>k</i>) == ch) &amp;&amp; (beginIndex &lt;= <i>k</i> &lt; endIndex)
* </pre></blockquote>
* is true. For other values of {@code ch}, it is the
* smallest value <i>k</i> such that:
* <blockquote><pre>
* (this.codePointAt(<i>k</i>) == ch) &amp;&amp; (beginIndex &lt;= <i>k</i> &lt; endIndex)
* </pre></blockquote>
* is true. In either case, if no such character occurs in this
* string at or after position {@code beginIndex} and before position
* {@code endIndex}, then {@code -1} is returned.
*
* <p>All indices are specified in {@code char} values
* (Unicode code units).
*
* @param ch a character (Unicode code point).
* @param beginIndex the index to start the search from (included).
* @param endIndex the index to stop the search at (excluded).
* @return the index of the first occurrence of the character in the
* character sequence represented by this object that is greater
* than or equal to {@code beginIndex} and less than {@code endIndex},
* or {@code -1} if the character does not occur.
* @throws StringIndexOutOfBoundsException if {@code beginIndex}
* is negative, or {@code endIndex} is larger than the length of
* this {@code String} object, or {@code beginIndex} is larger than
* {@code endIndex}.
* @since 21
*/
public int indexOf(int ch, int beginIndex, int endIndex) {
checkBoundsBeginEnd(beginIndex, endIndex, length());
return isLatin1() ? StringLatin1.indexOf(value, ch, beginIndex, endIndex)
: StringUTF16.indexOf(value, ch, beginIndex, endIndex);
}
/**
* Returns the index within this string of the last occurrence of
* the specified character. For values of {@code ch} in the
* range from 0 to 0xFFFF (inclusive), the index (in Unicode code
* units) returned is the largest value <i>k</i> such that:
* <blockquote><pre>
* this.charAt(<i>k</i>) == ch
* </pre></blockquote>
* is true. For other values of {@code ch}, it is the
* largest value <i>k</i> such that:
* <blockquote><pre>
* this.codePointAt(<i>k</i>) == ch
* </pre></blockquote>
* is true. In either case, if no such character occurs in this
* string, then {@code -1} is returned. The
* {@code String} is searched backwards starting at the last
* character.
*
* @param ch a character (Unicode code point).
* @return the index of the last occurrence of the character in the
* character sequence represented by this object, or
* {@code -1} if the character does not occur.
*/
public int lastIndexOf(int ch) {
return lastIndexOf(ch, length() - 1);
}
/**
* Returns the index within this string of the last occurrence of
* the specified character, searching backward starting at the
* specified index. For values of {@code ch} in the range
* from 0 to 0xFFFF (inclusive), the index returned is the largest
* value <i>k</i> such that:
* <blockquote><pre>
* (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> &lt;= fromIndex)
* </pre></blockquote>
* is true. For other values of {@code ch}, it is the
* largest value <i>k</i> such that:
* <blockquote><pre>
* (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> &lt;= fromIndex)
* </pre></blockquote>
* is true. In either case, if no such character occurs in this
* string at or before position {@code fromIndex}, then
* {@code -1} is returned.
*
* <p>All indices are specified in {@code char} values
* (Unicode code units).
*
* @param ch a character (Unicode code point).
* @param fromIndex the index to start the search from. There is no
* restriction on the value of {@code fromIndex}. If it is
* greater than or equal to the length of this string, it has
* the same effect as if it were equal to one less than the
* length of this string: this entire string may be searched.
* If it is negative, it has the same effect as if it were -1:
* -1 is returned.
* @return the index of the last occurrence of the character in the
* character sequence represented by this object that is less
* than or equal to {@code fromIndex}, or {@code -1}
* if the character does not occur before that point.
*/
public int lastIndexOf(int ch, int fromIndex) {
return isLatin1() ? StringLatin1.lastIndexOf(value, ch, fromIndex)
: StringUTF16.lastIndexOf(value, ch, fromIndex);
}
/**
* Returns the index within this string of the first occurrence of the
* specified substring.
*
* <p>The returned index is the smallest value {@code k} for which:
* <pre>{@code
* this.startsWith(str, k)
* }</pre>
* If no such value of {@code k} exists, then {@code -1} is returned.
*
* @param str the substring to search for.
* @return the index of the first occurrence of the specified substring,
* or {@code -1} if there is no such occurrence.
*/
public int indexOf(String str) {
byte coder = coder();
if (coder == str.coder()) {
return isLatin1() ? StringLatin1.indexOf(value, str.value)
: StringUTF16.indexOf(value, str.value);
}
if (coder == LATIN1) { // str.coder == UTF16
return -1;
}
return StringUTF16.indexOfLatin1(value, str.value);
}
/**
* Returns the index within this string of the first occurrence of the
* specified substring, starting at the specified index.
*
* <p>The returned index is the smallest value {@code k} for which:
* <pre>{@code
* k >= Math.min(fromIndex, this.length()) &&
* this.startsWith(str, k)
* }</pre>
* If no such value of {@code k} exists, then {@code -1} is returned.
*
* @apiNote
* Unlike {@link #substring(int)}, for example, this method does not throw
* an exception when {@code fromIndex} is outside the valid range.
* Rather, it returns -1 when {@code fromIndex} is larger than the length of
* the string.
* This result is, by itself, indistinguishable from a genuine absence of
* {@code str} in the string.
* If stricter behavior is needed, {@link #indexOf(String, int, int)}
* should be considered instead.
* On {@link String} {@code s} and a non-empty {@code str}, for example,
* {@code s.indexOf(str, fromIndex, s.length())} would throw if
* {@code fromIndex} were larger than the string length, or were negative.
*
* @param str the substring to search for.
* @param fromIndex the index from which to start the search.
* @return the index of the first occurrence of the specified substring,
* starting at the specified index,
* or {@code -1} if there is no such occurrence.
*/
public int indexOf(String str, int fromIndex) {
return indexOf(value, coder(), length(), str, fromIndex);
}
/**
* Returns the index of the first occurrence of the specified substring
* within the specified index range of {@code this} string.
*
* <p>This method returns the same result as the one of the invocation
* <pre>{@code
* s.substring(beginIndex, endIndex).indexOf(str) + beginIndex
* }</pre>
* if the index returned by {@link #indexOf(String)} is non-negative,
* and returns -1 otherwise.
* (No substring is instantiated, though.)
*
* @param str the substring to search for.
* @param beginIndex the index to start the search from (included).
* @param endIndex the index to stop the search at (excluded).
* @return the index of the first occurrence of the specified substring
* within the specified index range,
* or {@code -1} if there is no such occurrence.
* @throws StringIndexOutOfBoundsException if {@code beginIndex}
* is negative, or {@code endIndex} is larger than the length of
* this {@code String} object, or {@code beginIndex} is larger than
* {@code endIndex}.
* @since 21
*/
public int indexOf(String str, int beginIndex, int endIndex) {
if (str.length() == 1) {
/* Simple optimization, can be omitted without behavioral impact */
return indexOf(str.charAt(0), beginIndex, endIndex);
}
checkBoundsBeginEnd(beginIndex, endIndex, length());
return indexOf(value, coder(), endIndex, str, beginIndex);
}
/**
* Code shared by String and AbstractStringBuilder to do searches. The
* source is the character array being searched, and the target
* is the string being searched for.
*
* @param src the characters being searched.
* @param srcCoder the coder of the source string.
* @param srcCount last index (exclusive) in the source string.
* @param tgtStr the characters being searched for.
* @param fromIndex the index to begin searching from.
*/
static int indexOf(byte[] src, byte srcCoder, int srcCount,
String tgtStr, int fromIndex) {
fromIndex = Math.clamp(fromIndex, 0, srcCount);
int tgtCount = tgtStr.length();
if (tgtCount > srcCount - fromIndex) {
return -1;
}
if (tgtCount == 0) {
return fromIndex;
}
byte[] tgt = tgtStr.value;
byte tgtCoder = tgtStr.coder();
if (srcCoder == tgtCoder) {
return srcCoder == LATIN1
? StringLatin1.indexOf(src, srcCount, tgt, tgtCount, fromIndex)
: StringUTF16.indexOf(src, srcCount, tgt, tgtCount, fromIndex);
}
if (srcCoder == LATIN1) { // && tgtCoder == UTF16
return -1;
}
// srcCoder == UTF16 && tgtCoder == LATIN1) {
return StringUTF16.indexOfLatin1(src, srcCount, tgt, tgtCount, fromIndex);
}
/**
* Returns the index within this string of the last occurrence of the
* specified substring. The last occurrence of the empty string ""
* is considered to occur at the index value {@code this.length()}.
*
* <p>The returned index is the largest value {@code k} for which:
* <pre>{@code
* this.startsWith(str, k)
* }</pre>
* If no such value of {@code k} exists, then {@code -1} is returned.
*
* @param str the substring to search for.
* @return the index of the last occurrence of the specified substring,
* or {@code -1} if there is no such occurrence.
*/
public int lastIndexOf(String str) {
return lastIndexOf(str, length());
}
/**
* Returns the index within this string of the last occurrence of the
* specified substring, searching backward starting at the specified index.
*
* <p>The returned index is the largest value {@code k} for which:
* <pre>{@code
* k <= Math.min(fromIndex, this.length()) &&
* this.startsWith(str, k)
* }</pre>
* If no such value of {@code k} exists, then {@code -1} is returned.
*
* @param str the substring to search for.
* @param fromIndex the index to start the search from.
* @return the index of the last occurrence of the specified substring,
* searching backward from the specified index,
* or {@code -1} if there is no such occurrence.
*/
public int lastIndexOf(String str, int fromIndex) {
return lastIndexOf(value, coder(), length(), str, fromIndex);
}
/**
* Code shared by String and AbstractStringBuilder to do searches. The
* source is the character array being searched, and the target
* is the string being searched for.
*
* @param src the characters being searched.
* @param srcCoder coder handles the mapping between bytes/chars
* @param srcCount count of the source string.
* @param tgtStr the characters being searched for.
* @param fromIndex the index to begin searching from.
*/
static int lastIndexOf(byte[] src, byte srcCoder, int srcCount,
String tgtStr, int fromIndex) {
byte[] tgt = tgtStr.value;
byte tgtCoder = tgtStr.coder();
int tgtCount = tgtStr.length();
/*
* Check arguments; return immediately where possible. For
* consistency, don't check for null str.
*/
int rightIndex = srcCount - tgtCount;
if (fromIndex > rightIndex) {
fromIndex = rightIndex;
}
if (fromIndex < 0) {
return -1;
}
/* Empty string always matches. */
if (tgtCount == 0) {
return fromIndex;
}
if (srcCoder == tgtCoder) {
return srcCoder == LATIN1
? StringLatin1.lastIndexOf(src, srcCount, tgt, tgtCount, fromIndex)
: StringUTF16.lastIndexOf(src, srcCount, tgt, tgtCount, fromIndex);
}
if (srcCoder == LATIN1) { // && tgtCoder == UTF16
return -1;
}
// srcCoder == UTF16 && tgtCoder == LATIN1
return StringUTF16.lastIndexOfLatin1(src, srcCount, tgt, tgtCount, fromIndex);
}
/**
* Returns a string that is a substring of this string. The
* substring begins with the character at the specified index and
* extends to the end of this string. <p>
* Examples:
* <blockquote><pre>
* "unhappy".substring(2) returns "happy"
* "Harbison".substring(3) returns "bison"
* "emptiness".substring(9) returns "" (an empty string)
* </pre></blockquote>
*
* @param beginIndex the beginning index, inclusive.
* @return the specified substring.
* @throws IndexOutOfBoundsException if
* {@code beginIndex} is negative or larger than the
* length of this {@code String} object.
*/
public String substring(int beginIndex) {
return substring(beginIndex, length());
}
/**
* Returns a string that is a substring of this string. The
* substring begins at the specified {@code beginIndex} and
* extends to the character at index {@code endIndex - 1}.
* Thus the length of the substring is {@code endIndex-beginIndex}.
* <p>
* Examples:
* <blockquote><pre>
* "hamburger".substring(4, 8) returns "urge"
* "smiles".substring(1, 5) returns "mile"
* </pre></blockquote>
*
* @param beginIndex the beginning index, inclusive.
* @param endIndex the ending index, exclusive.
* @return the specified substring.
* @throws IndexOutOfBoundsException if the
* {@code beginIndex} is negative, or
* {@code endIndex} is larger than the length of
* this {@code String} object, or
* {@code beginIndex} is larger than
* {@code endIndex}.
*/
public String substring(int beginIndex, int endIndex) {
int length = length();
checkBoundsBeginEnd(beginIndex, endIndex, length);
if (beginIndex == 0 && endIndex == length) {
return this;
}
int subLen = endIndex - beginIndex;
return isLatin1() ? StringLatin1.newString(value, beginIndex, subLen)
: StringUTF16.newString(value, beginIndex, subLen);
}
/**
* Returns a character sequence that is a subsequence of this sequence.
*
* <p> An invocation of this method of the form
*
* <blockquote><pre>
* str.subSequence(begin,&nbsp;end)</pre></blockquote>
*
* behaves in exactly the same way as the invocation
*
* <blockquote><pre>
* str.substring(begin,&nbsp;end)</pre></blockquote>
*
* @apiNote
* This method is defined so that the {@code String} class can implement
* the {@link CharSequence} interface.
*
* @param beginIndex the begin index, inclusive.
* @param endIndex the end index, exclusive.
* @return the specified subsequence.
*
* @throws IndexOutOfBoundsException
* if {@code beginIndex} or {@code endIndex} is negative,
* if {@code endIndex} is greater than {@code length()},
* or if {@code beginIndex} is greater than {@code endIndex}
*
* @since 1.4
*/
public CharSequence subSequence(int beginIndex, int endIndex) {
return this.substring(beginIndex, endIndex);
}
/**
* Concatenates the specified string to the end of this string.
* <p>
* If the length of the argument string is {@code 0}, then this
* {@code String} object is returned. Otherwise, a
* {@code String} object is returned that represents a character
* sequence that is the concatenation of the character sequence
* represented by this {@code String} object and the character
* sequence represented by the argument string.<p>
* Examples:
* <blockquote><pre>
* "cares".concat("s") returns "caress"
* "to".concat("get").concat("her") returns "together"
* </pre></blockquote>
*
* @param str the {@code String} that is concatenated to the end
* of this {@code String}.
* @return a string that represents the concatenation of this object's
* characters followed by the string argument's characters.
*/
public String concat(String str) {
if (str.isEmpty()) {
return this;
}
return StringConcatHelper.doConcat(this, str);
}
/**
* Returns a string resulting from replacing all occurrences of
* {@code oldChar} in this string with {@code newChar}.
* <p>
* If the character {@code oldChar} does not occur in the
* character sequence represented by this {@code String} object,
* then a reference to this {@code String} object is returned.
* Otherwise, a {@code String} object is returned that
* represents a character sequence identical to the character sequence
* represented by this {@code String} object, except that every
* occurrence of {@code oldChar} is replaced by an occurrence
* of {@code newChar}.
* <p>
* Examples:
* <blockquote><pre>
* "mesquite in your cellar".replace('e', 'o')
* returns "mosquito in your collar"
* "the war of baronets".replace('r', 'y')
* returns "the way of bayonets"
* "sparring with a purple porpoise".replace('p', 't')
* returns "starring with a turtle tortoise"
* "JonL".replace('q', 'x') returns "JonL" (no change)
* </pre></blockquote>
*
* @param oldChar the old character.
* @param newChar the new character.
* @return a string derived from this string by replacing every
* occurrence of {@code oldChar} with {@code newChar}.
*/
public String replace(char oldChar, char newChar) {
if (oldChar != newChar) {
String ret = isLatin1() ? StringLatin1.replace(value, oldChar, newChar)
: StringUTF16.replace(value, oldChar, newChar);
if (ret != null) {
return ret;
}
}
return this;
}
/**
* Tells whether or not this string matches the given <a
* href="../util/regex/Pattern.html#sum">regular expression</a>.
*
* <p> An invocation of this method of the form
* <i>str</i>{@code .matches(}<i>regex</i>{@code )} yields exactly the
* same result as the expression
*
* <blockquote>
* {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#matches(String,CharSequence)
* matches(<i>regex</i>, <i>str</i>)}
* </blockquote>
*
* @param regex
* the regular expression to which this string is to be matched
*
* @return {@code true} if, and only if, this string matches the
* given regular expression
*
* @throws PatternSyntaxException
* if the regular expression's syntax is invalid
*
* @see java.util.regex.Pattern
*
* @since 1.4
*/
public boolean matches(String regex) {
return Pattern.matches(regex, this);
}
/**
* Returns true if and only if this string contains the specified
* sequence of char values.
*
* @param s the sequence to search for
* @return true if this string contains {@code s}, false otherwise
* @since 1.5
*/
public boolean contains(CharSequence s) {
return indexOf(s.toString()) >= 0;
}
/**
* Replaces the first substring of this string that matches the given <a
* href="../util/regex/Pattern.html#sum">regular expression</a> with the
* given replacement.
*
* <p> An invocation of this method of the form
* <i>str</i>{@code .replaceFirst(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
* yields exactly the same result as the expression
*
* <blockquote>
* <code>
* {@link java.util.regex.Pattern}.{@link
* java.util.regex.Pattern#compile(String) compile}(<i>regex</i>).{@link
* java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link
* java.util.regex.Matcher#replaceFirst(String) replaceFirst}(<i>repl</i>)
* </code>
* </blockquote>
*
*<p>
* Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
* replacement string may cause the results to be different than if it were
* being treated as a literal replacement string; see
* {@link java.util.regex.Matcher#replaceFirst}.
* Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
* meaning of these characters, if desired.
*
* @param regex
* the regular expression to which this string is to be matched
* @param replacement
* the string to be substituted for the first match
*
* @return The resulting {@code String}
*
* @throws PatternSyntaxException
* if the regular expression's syntax is invalid
*
* @see java.util.regex.Pattern
*
* @since 1.4
*/
public String replaceFirst(String regex, String replacement) {
return Pattern.compile(regex).matcher(this).replaceFirst(replacement);
}
/**
* Replaces each substring of this string that matches the given <a
* href="../util/regex/Pattern.html#sum">regular expression</a> with the
* given replacement.
*
* <p> An invocation of this method of the form
* <i>str</i>{@code .replaceAll(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
* yields exactly the same result as the expression
*
* <blockquote>
* <code>
* {@link java.util.regex.Pattern}.{@link
* java.util.regex.Pattern#compile(String) compile}(<i>regex</i>).{@link
* java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link
* java.util.regex.Matcher#replaceAll(String) replaceAll}(<i>repl</i>)
* </code>
* </blockquote>
*
*<p>
* Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
* replacement string may cause the results to be different than if it were
* being treated as a literal replacement string; see
* {@link java.util.regex.Matcher#replaceAll Matcher.replaceAll}.
* Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
* meaning of these characters, if desired.
*
* @param regex
* the regular expression to which this string is to be matched
* @param replacement
* the string to be substituted for each match
*
* @return The resulting {@code String}
*
* @throws PatternSyntaxException
* if the regular expression's syntax is invalid
*
* @see java.util.regex.Pattern
*
* @since 1.4
*/
public String replaceAll(String regex, String replacement) {
return Pattern.compile(regex).matcher(this).replaceAll(replacement);
}
/**
* Replaces each substring of this string that matches the literal target
* sequence with the specified literal replacement sequence. The
* replacement proceeds from the beginning of the string to the end, for
* example, replacing "aa" with "b" in the string "aaa" will result in
* "ba" rather than "ab".
*
* @param target The sequence of char values to be replaced
* @param replacement The replacement sequence of char values
* @return The resulting string
* @since 1.5
*/
public String replace(CharSequence target, CharSequence replacement) {
String trgtStr = target.toString();
String replStr = replacement.toString();
int thisLen = length();
int trgtLen = trgtStr.length();
int replLen = replStr.length();
if (trgtLen > 0) {
if (trgtLen == 1 && replLen == 1) {
return replace(trgtStr.charAt(0), replStr.charAt(0));
}
boolean thisIsLatin1 = this.isLatin1();
boolean trgtIsLatin1 = trgtStr.isLatin1();
boolean replIsLatin1 = replStr.isLatin1();
String ret = (thisIsLatin1 && trgtIsLatin1 && replIsLatin1)
? StringLatin1.replace(value, thisLen,
trgtStr.value, trgtLen,
replStr.value, replLen)
: StringUTF16.replace(value, thisLen, thisIsLatin1,
trgtStr.value, trgtLen, trgtIsLatin1,
replStr.value, replLen, replIsLatin1);
if (ret != null) {
return ret;
}
return this;
} else { // trgtLen == 0
int resultLen;
try {
resultLen = Math.addExact(thisLen, Math.multiplyExact(
Math.addExact(thisLen, 1), replLen));
} catch (ArithmeticException ignored) {
throw new OutOfMemoryError("Required length exceeds implementation limit");
}
StringBuilder sb = new StringBuilder(resultLen);
sb.append(replStr);
for (int i = 0; i < thisLen; ++i) {
sb.append(charAt(i)).append(replStr);
}
return sb.toString();
}
}
/**
* Splits this string around matches of the given
* <a href="../util/regex/Pattern.html#sum">regular expression</a>.
*
* <p> The array returned by this method contains each substring of this
* string that is terminated by another substring that matches the given
* expression or is terminated by the end of the string. The substrings in
* the array are in the order in which they occur in this string. If the
* expression does not match any part of the input then the resulting array
* has just one element, namely this string.
*
* <p> When there is a positive-width match at the beginning of this
* string then an empty leading substring is included at the beginning
* of the resulting array. A zero-width match at the beginning however
* never produces such empty leading substring.
*
* <p> The {@code limit} parameter controls the number of times the
* pattern is applied and therefore affects the length of the resulting
* array.
* <ul>
* <li><p>
* If the <i>limit</i> is positive then the pattern will be applied
* at most <i>limit</i>&nbsp;-&nbsp;1 times, the array's length will be
* no greater than <i>limit</i>, and the array's last entry will contain
* all input beyond the last matched delimiter.</p></li>
*
* <li><p>
* If the <i>limit</i> is zero then the pattern will be applied as
* many times as possible, the array can have any length, and trailing
* empty strings will be discarded.</p></li>
*
* <li><p>
* If the <i>limit</i> is negative then the pattern will be applied
* as many times as possible and the array can have any length.</p></li>
* </ul>
*
* <p> The string {@code "boo:and:foo"}, for example, yields the
* following results with these parameters:
*
* <blockquote><table class="plain">
* <caption style="display:none">Split example showing regex, limit, and result</caption>
* <thead>
* <tr>
* <th scope="col">Regex</th>
* <th scope="col">Limit</th>
* <th scope="col">Result</th>
* </tr>
* </thead>
* <tbody>
* <tr><th scope="row" rowspan="3" style="font-weight:normal">:</th>
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">2</th>
* <td>{@code { "boo", "and:foo" }}</td></tr>
* <tr><!-- : -->
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">5</th>
* <td>{@code { "boo", "and", "foo" }}</td></tr>
* <tr><!-- : -->
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">-2</th>
* <td>{@code { "boo", "and", "foo" }}</td></tr>
* <tr><th scope="row" rowspan="3" style="font-weight:normal">o</th>
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">5</th>
* <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
* <tr><!-- o -->
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">-2</th>
* <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
* <tr><!-- o -->
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">0</th>
* <td>{@code { "b", "", ":and:f" }}</td></tr>
* </tbody>
* </table></blockquote>
*
* <p> An invocation of this method of the form
* <i>str.</i>{@code split(}<i>regex</i>{@code ,}&nbsp;<i>n</i>{@code )}
* yields the same result as the expression
*
* <blockquote>
* <code>
* {@link java.util.regex.Pattern}.{@link
* java.util.regex.Pattern#compile(String) compile}(<i>regex</i>).{@link
* java.util.regex.Pattern#split(java.lang.CharSequence,int) split}(<i>str</i>,&nbsp;<i>n</i>)
* </code>
* </blockquote>
*
*
* @param regex
* the delimiting regular expression
*
* @param limit
* the result threshold, as described above
*
* @return the array of strings computed by splitting this string
* around matches of the given regular expression
*
* @throws PatternSyntaxException
* if the regular expression's syntax is invalid
*
* @see java.util.regex.Pattern
*
* @since 1.4
*/
public String[] split(String regex, int limit) {
return split(regex, limit, false);
}
/**
* Splits this string around matches of the given regular expression and
* returns both the strings and the matching delimiters.
*
* <p> The array returned by this method contains each substring of this
* string that is terminated by another substring that matches the given
* expression or is terminated by the end of the string.
* Each substring is immediately followed by the subsequence (the delimiter)
* that matches the given expression, <em>except</em> for the last
* substring, which is not followed by anything.
* The substrings in the array and the delimiters are in the order in which
* they occur in the input.
* If the expression does not match any part of the input then the resulting
* array has just one element, namely this string.
*
* <p> When there is a positive-width match at the beginning of this
* string then an empty leading substring is included at the beginning
* of the resulting array. A zero-width match at the beginning however
* never produces such empty leading substring nor the empty delimiter.
*
* <p> The {@code limit} parameter controls the number of times the
* pattern is applied and therefore affects the length of the resulting
* array.
* <ul>
* <li> If the <i>limit</i> is positive then the pattern will be applied
* at most <i>limit</i>&nbsp;-&nbsp;1 times, the array's length will be
* no greater than 2 &times; <i>limit</i> - 1, and the array's last
* entry will contain all input beyond the last matched delimiter.</li>
*
* <li> If the <i>limit</i> is zero then the pattern will be applied as
* many times as possible, the array can have any length, and trailing
* empty strings will be discarded.</li>
*
* <li> If the <i>limit</i> is negative then the pattern will be applied
* as many times as possible and the array can have any length.</li>
* </ul>
*
* <p> The input {@code "boo:::and::foo"}, for example, yields the following
* results with these parameters:
*
* <table class="plain" style="margin-left:2em;">
* <caption style="display:none">Split example showing regex, limit, and result</caption>
* <thead>
* <tr>
* <th scope="col">Regex</th>
* <th scope="col">Limit</th>
* <th scope="col">Result</th>
* </tr>
* </thead>
* <tbody>
* <tr><th scope="row" rowspan="3" style="font-weight:normal">:+</th>
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">2</th>
* <td>{@code { "boo", ":::", "and::foo" }}</td></tr>
* <tr><!-- : -->
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">5</th>
* <td>{@code { "boo", ":::", "and", "::", "foo" }}</td></tr>
* <tr><!-- : -->
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">-1</th>
* <td>{@code { "boo", ":::", "and", "::", "foo" }}</td></tr>
* <tr><th scope="row" rowspan="3" style="font-weight:normal">o</th>
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">5</th>
* <td>{@code { "b", "o", "", "o", ":::and::f", "o", "", "o", "" }}</td></tr>
* <tr><!-- o -->
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">-1</th>
* <td>{@code { "b", "o", "", "o", ":::and::f", "o", "", "o", "" }}</td></tr>
* <tr><!-- o -->
* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">0</th>
* <td>{@code { "b", "o", "", "o", ":::and::f", "o", "", "o" }}</td></tr>
* </tbody>
* </table>
*
* @apiNote An invocation of this method of the form
* <i>str.</i>{@code splitWithDelimiters(}<i>regex</i>{@code ,}&nbsp;<i>n</i>{@code )}
* yields the same result as the expression
*
* <blockquote>
* <code>
* {@link java.util.regex.Pattern}.{@link
* java.util.regex.Pattern#compile(String) compile}(<i>regex</i>).{@link
* java.util.regex.Pattern#splitWithDelimiters(CharSequence,int) splitWithDelimiters}(<i>str</i>,&nbsp;<i>n</i>)
* </code>
* </blockquote>
*
* @param regex
* the delimiting regular expression
*
* @param limit
* the result threshold, as described above
*
* @return the array of strings computed by splitting this string
* around matches of the given regular expression, alternating
* substrings and matching delimiters
*
* @since 21
*/
public String[] splitWithDelimiters(String regex, int limit) {
return split(regex, limit, true);
}
private String[] split(String regex, int limit, boolean withDelimiters) {
/* fastpath if the regex is a
* (1) one-char String and this character is not one of the
* RegEx's meta characters ".$|()[{^?*+\\", or
* (2) two-char String and the first char is the backslash and
* the second is not the ascii digit or ascii letter.
*/
char ch = 0;
if (((regex.length() == 1 &&
".$|()[{^?*+\\".indexOf(ch = regex.charAt(0)) == -1) ||
(regex.length() == 2 &&
regex.charAt(0) == '\\' &&
(((ch = regex.charAt(1))-'0')|('9'-ch)) < 0 &&
((ch-'a')|('z'-ch)) < 0 &&
((ch-'A')|('Z'-ch)) < 0)) &&
(ch < Character.MIN_HIGH_SURROGATE ||
ch > Character.MAX_LOW_SURROGATE))
{
// All the checks above can potentially be constant folded by
// a JIT/AOT compiler when the regex is a constant string.
// That requires method inlining of the checks, which is only
// possible when the actual split logic is in a separate method
// because the large split loop can usually not be inlined.
return split(ch, limit, withDelimiters);
}
Pattern pattern = Pattern.compile(regex);
return withDelimiters
? pattern.splitWithDelimiters(this, limit)
: pattern.split(this, limit);
}
private String[] split(char ch, int limit, boolean withDelimiters) {
int matchCount = 0;
int off = 0;
int next;
boolean limited = limit > 0;
ArrayList<String> list = new ArrayList<>();
String del = withDelimiters ? String.valueOf(ch) : null;
while ((next = indexOf(ch, off)) != -1) {
if (!limited || matchCount < limit - 1) {
list.add(substring(off, next));
if (withDelimiters) {
list.add(del);
}
off = next + 1;
++matchCount;
} else { // last one
int last = length();
list.add(substring(off, last));
off = last;
++matchCount;
break;
}
}
// If no match was found, return this
if (off == 0)
return new String[] {this};
// Add remaining segment
if (!limited || matchCount < limit)
list.add(substring(off, length()));
// Construct result
int resultSize = list.size();
if (limit == 0) {
while (resultSize > 0 && list.get(resultSize - 1).isEmpty()) {
resultSize--;
}
}
String[] result = new String[resultSize];
return list.subList(0, resultSize).toArray(result);
}
/**
* Splits this string around matches of the given <a
* href="../util/regex/Pattern.html#sum">regular expression</a>.
*
* <p> This method works as if by invoking the two-argument {@link
* #split(String, int) split} method with the given expression and a limit
* argument of zero. Trailing empty strings are therefore not included in
* the resulting array.
*
* <p> The string {@code "boo:and:foo"}, for example, yields the following
* results with these expressions:
*
* <blockquote><table class="plain">
* <caption style="display:none">Split examples showing regex and result</caption>
* <thead>
* <tr>
* <th scope="col">Regex</th>
* <th scope="col">Result</th>
* </tr>
* </thead>
* <tbody>
* <tr><th scope="row" style="font-weight:normal">:</th>
* <td>{@code { "boo", "and", "foo" }}</td></tr>
* <tr><th scope="row" style="font-weight:normal">o</th>
* <td>{@code { "b", "", ":and:f" }}</td></tr>
* </tbody>
* </table></blockquote>
*
*
* @param regex
* the delimiting regular expression
*
* @return the array of strings computed by splitting this string
* around matches of the given regular expression
*
* @throws PatternSyntaxException
* if the regular expression's syntax is invalid
*
* @see java.util.regex.Pattern
*
* @since 1.4
*/
public String[] split(String regex) {
return split(regex, 0, false);
}
/**
* Returns a new String composed of copies of the
* {@code CharSequence elements} joined together with a copy of
* the specified {@code delimiter}.
*
* <blockquote>For example,
* <pre>{@code
* String message = String.join("-", "Java", "is", "cool");
* // message returned is: "Java-is-cool"
* }</pre></blockquote>
*
* Note that if an element is null, then {@code "null"} is added.
*
* @param delimiter the delimiter that separates each element
* @param elements the elements to join together.
*
* @return a new {@code String} that is composed of the {@code elements}
* separated by the {@code delimiter}
*
* @throws NullPointerException If {@code delimiter} or {@code elements}
* is {@code null}
*
* @see java.util.StringJoiner
* @since 1.8
*/
public static String join(CharSequence delimiter, CharSequence... elements) {
var delim = delimiter.toString();
var elems = new String[elements.length];
for (int i = 0; i < elements.length; i++) {
elems[i] = String.valueOf(elements[i]);
}
return join("", "", delim, elems, elems.length);
}
/**
* Designated join routine.
*
* @param prefix the non-null prefix
* @param suffix the non-null suffix
* @param delimiter the non-null delimiter
* @param elements the non-null array of non-null elements
* @param size the number of elements in the array (<= elements.length)
* @return the joined string
*/
@ForceInline
static String join(String prefix, String suffix, String delimiter, String[] elements, int size) {
int icoder = prefix.coder() | suffix.coder();
long len = (long) prefix.length() + suffix.length();
if (size > 1) { // when there are more than one element, size - 1 delimiters will be emitted
len += (long) (size - 1) * delimiter.length();
icoder |= delimiter.coder();
}
// assert len > 0L; // max: (long) Integer.MAX_VALUE << 32
// following loop will add max: (long) Integer.MAX_VALUE * Integer.MAX_VALUE to len
// so len can overflow at most once
for (int i = 0; i < size; i++) {
var el = elements[i];
len += el.length();
icoder |= el.coder();
}
byte coder = (byte) icoder;
// long len overflow check, char -> byte length, int len overflow check
if (len < 0L || (len <<= coder) != (int) len) {
throw new OutOfMemoryError("Requested string length exceeds VM limit");
}
byte[] value = StringConcatHelper.newArray(len);
int off = 0;
prefix.getBytes(value, off, coder); off += prefix.length();
if (size > 0) {
var el = elements[0];
el.getBytes(value, off, coder); off += el.length();
for (int i = 1; i < size; i++) {
delimiter.getBytes(value, off, coder); off += delimiter.length();
el = elements[i];
el.getBytes(value, off, coder); off += el.length();
}
}
suffix.getBytes(value, off, coder);
// assert off + suffix.length() == value.length >> coder;
return new String(value, coder);
}
/**
* Returns a new {@code String} composed of copies of the
* {@code CharSequence elements} joined together with a copy of the
* specified {@code delimiter}.
*
* <blockquote>For example,
* <pre>{@code
* List<String> strings = List.of("Java", "is", "cool");
* String message = String.join(" ", strings);
* // message returned is: "Java is cool"
*
* Set<String> strings =
* new LinkedHashSet<>(List.of("Java", "is", "very", "cool"));
* String message = String.join("-", strings);
* // message returned is: "Java-is-very-cool"
* }</pre></blockquote>
*
* Note that if an individual element is {@code null}, then {@code "null"} is added.
*
* @param delimiter a sequence of characters that is used to separate each
* of the {@code elements} in the resulting {@code String}
* @param elements an {@code Iterable} that will have its {@code elements}
* joined together.
*
* @return a new {@code String} that is composed from the {@code elements}
* argument
*
* @throws NullPointerException If {@code delimiter} or {@code elements}
* is {@code null}
*
* @see #join(CharSequence,CharSequence...)
* @see java.util.StringJoiner
* @since 1.8
*/
public static String join(CharSequence delimiter,
Iterable<? extends CharSequence> elements) {
Objects.requireNonNull(delimiter);
Objects.requireNonNull(elements);
var delim = delimiter.toString();
var elems = new String[8];
int size = 0;
for (CharSequence cs: elements) {
if (size >= elems.length) {
elems = Arrays.copyOf(elems, elems.length << 1);
}
elems[size++] = String.valueOf(cs);
}
return join("", "", delim, elems, size);
}
/**
* Converts all of the characters in this {@code String} to lower
* case using the rules of the given {@code Locale}. Case mapping is based
* on the Unicode Standard version specified by the {@link java.lang.Character Character}
* class. Since case mappings are not always 1:1 char mappings, the resulting {@code String}
* and this {@code String} may differ in length.
* <p>
* Examples of lowercase mappings are in the following table:
* <table class="plain">
* <caption style="display:none">Lowercase mapping examples showing language code of locale, upper case, lower case, and description</caption>
* <thead>
* <tr>
* <th scope="col">Language Code of Locale</th>
* <th scope="col">Upper Case</th>
* <th scope="col">Lower Case</th>
* <th scope="col">Description</th>
* </tr>
* </thead>
* <tbody>
* <tr>
* <td>tr (Turkish)</td>
* <th scope="row" style="font-weight:normal; text-align:left">&#92;u0130</th>
* <td>&#92;u0069</td>
* <td>capital letter I with dot above -&gt; small letter i</td>
* </tr>
* <tr>
* <td>tr (Turkish)</td>
* <th scope="row" style="font-weight:normal; text-align:left">&#92;u0049</th>
* <td>&#92;u0131</td>
* <td>capital letter I -&gt; small letter dotless i </td>
* </tr>
* <tr>
* <td>(all)</td>
* <th scope="row" style="font-weight:normal; text-align:left">French Fries</th>
* <td>french fries</td>
* <td>lowercased all chars in String</td>
* </tr>
* <tr>
* <td>(all)</td>
* <th scope="row" style="font-weight:normal; text-align:left">
* &Iota;&Chi;&Theta;&Upsilon;&Sigma;</th>
* <td>&iota;&chi;&theta;&upsilon;&sigma;</td>
* <td>lowercased all chars in String</td>
* </tr>
* </tbody>
* </table>
*
* @param locale use the case transformation rules for this locale
* @return the {@code String}, converted to lowercase.
* @see java.lang.String#toLowerCase()
* @see java.lang.String#toUpperCase()
* @see java.lang.String#toUpperCase(Locale)
* @since 1.1
*/
public String toLowerCase(Locale locale) {
return isLatin1() ? StringLatin1.toLowerCase(this, value, locale)
: StringUTF16.toLowerCase(this, value, locale);
}
/**
* Converts all of the characters in this {@code String} to lower
* case using the rules of the default locale. This method is equivalent to
* {@code toLowerCase(Locale.getDefault())}.
*
* @apiNote This method is locale sensitive, and may produce unexpected
* results if used for strings that are intended to be interpreted locale
* independently.
* Examples are programming language identifiers, protocol keys, and HTML
* tags.
* For instance, {@code "TITLE".toLowerCase()} in a Turkish locale
* returns {@code "t\u005Cu0131tle"}, where '\u005Cu0131' is the
* LATIN SMALL LETTER DOTLESS I character.
* To obtain correct results for locale insensitive strings, use
* {@code toLowerCase(Locale.ROOT)}.
*
* @return the {@code String}, converted to lowercase.
* @see java.lang.String#toLowerCase(Locale)
*/
public String toLowerCase() {
return toLowerCase(Locale.getDefault());
}
/**
* Converts all of the characters in this {@code String} to upper
* case using the rules of the given {@code Locale}. Case mapping is based
* on the Unicode Standard version specified by the {@link java.lang.Character Character}
* class. Since case mappings are not always 1:1 char mappings, the resulting {@code String}
* and this {@code String} may differ in length.
* <p>
* Examples of locale-sensitive and 1:M case mappings are in the following table:
* <table class="plain">
* <caption style="display:none">Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description.</caption>
* <thead>
* <tr>
* <th scope="col">Language Code of Locale</th>
* <th scope="col">Lower Case</th>
* <th scope="col">Upper Case</th>
* <th scope="col">Description</th>
* </tr>
* </thead>
* <tbody>
* <tr>
* <td>tr (Turkish)</td>
* <th scope="row" style="font-weight:normal; text-align:left">&#92;u0069</th>
* <td>&#92;u0130</td>
* <td>small letter i -&gt; capital letter I with dot above</td>
* </tr>
* <tr>
* <td>tr (Turkish)</td>
* <th scope="row" style="font-weight:normal; text-align:left">&#92;u0131</th>
* <td>&#92;u0049</td>
* <td>small letter dotless i -&gt; capital letter I</td>
* </tr>
* <tr>
* <td>(all)</td>
* <th scope="row" style="font-weight:normal; text-align:left">&#92;u00df</th>
* <td>&#92;u0053 &#92;u0053</td>
* <td>small letter sharp s -&gt; two letters: SS</td>
* </tr>
* <tr>
* <td>(all)</td>
* <th scope="row" style="font-weight:normal; text-align:left">Fahrvergn&uuml;gen</th>
* <td>FAHRVERGN&Uuml;GEN</td>
* <td></td>
* </tr>
* </tbody>
* </table>
* @param locale use the case transformation rules for this locale
* @return the {@code String}, converted to uppercase.
* @see java.lang.String#toUpperCase()
* @see java.lang.String#toLowerCase()
* @see java.lang.String#toLowerCase(Locale)
* @since 1.1
*/
public String toUpperCase(Locale locale) {
return isLatin1() ? StringLatin1.toUpperCase(this, value, locale)
: StringUTF16.toUpperCase(this, value, locale);
}
/**
* Converts all of the characters in this {@code String} to upper
* case using the rules of the default locale. This method is equivalent to
* {@code toUpperCase(Locale.getDefault())}.
*
* @apiNote This method is locale sensitive, and may produce unexpected
* results if used for strings that are intended to be interpreted locale
* independently.
* Examples are programming language identifiers, protocol keys, and HTML
* tags.
* For instance, {@code "title".toUpperCase()} in a Turkish locale
* returns {@code "T\u005Cu0130TLE"}, where '\u005Cu0130' is the
* LATIN CAPITAL LETTER I WITH DOT ABOVE character.
* To obtain correct results for locale insensitive strings, use
* {@code toUpperCase(Locale.ROOT)}.
*
* @return the {@code String}, converted to uppercase.
* @see java.lang.String#toUpperCase(Locale)
*/
public String toUpperCase() {
return toUpperCase(Locale.getDefault());
}
/**
* Returns a string whose value is this string, with all leading
* and trailing space removed, where space is defined
* as any character whose codepoint is less than or equal to
* {@code 'U+0020'} (the space character).
* <p>
* If this {@code String} object represents an empty character
* sequence, or the first and last characters of character sequence
* represented by this {@code String} object both have codes
* that are not space (as defined above), then a
* reference to this {@code String} object is returned.
* <p>
* Otherwise, if all characters in this string are space (as
* defined above), then a {@code String} object representing an
* empty string is returned.
* <p>
* Otherwise, let <i>k</i> be the index of the first character in the
* string whose code is not a space (as defined above) and let
* <i>m</i> be the index of the last character in the string whose code
* is not a space (as defined above). A {@code String}
* object is returned, representing the substring of this string that
* begins with the character at index <i>k</i> and ends with the
* character at index <i>m</i>-that is, the result of
* {@code this.substring(k, m + 1)}.
*
* @apiNote
* This method removes leading and trailing space characters and ASCII control
* characters from the string. To remove characters using a Unicode-based definition of
* {@linkplain Character#isWhitespace(int) white space}, use {@link #strip() strip},
* {@link #stripIndent() stripIndent}, {@link #stripLeading() stripLeading}, or
* {@link #stripTrailing() stripTrailing}.
*
* @return a string whose value is this string, with all leading
* and trailing space removed, or this string if it
* has no leading or trailing space.
*/
public String trim() {
String ret = isLatin1() ? StringLatin1.trim(value)
: StringUTF16.trim(value);
return ret == null ? this : ret;
}
/**
* Returns a string whose value is this string, with all leading
* and trailing {@linkplain Character#isWhitespace(int) white space}
* removed.
* <p>
* If this {@code String} object represents an empty string,
* or if all code points in this string are
* {@linkplain Character#isWhitespace(int) white space}, then an empty string
* is returned.
* <p>
* Otherwise, returns a substring of this string beginning with the first
* code point that is not a {@linkplain Character#isWhitespace(int) white space}
* up to and including the last code point that is not a
* {@linkplain Character#isWhitespace(int) white space}.
* <p>
* This method may be used to strip
* {@linkplain Character#isWhitespace(int) white space} from
* the beginning and end of a string.
*
* @return a string whose value is this string, with all leading
* and trailing white space removed
*
* @see Character#isWhitespace(int)
*
* @since 11
*/
public String strip() {
String ret = isLatin1() ? StringLatin1.strip(value)
: StringUTF16.strip(value);
return ret == null ? this : ret;
}
/**
* Returns a string whose value is this string, with all leading
* {@linkplain Character#isWhitespace(int) white space} removed.
* <p>
* If this {@code String} object represents an empty string,
* or if all code points in this string are
* {@linkplain Character#isWhitespace(int) white space}, then an empty string
* is returned.
* <p>
* Otherwise, returns a substring of this string beginning with the first
* code point that is not a {@linkplain Character#isWhitespace(int) white space}
* up to and including the last code point of this string.
* <p>
* This method may be used to trim
* {@linkplain Character#isWhitespace(int) white space} from
* the beginning of a string.
*
* @return a string whose value is this string, with all leading white
* space removed
*
* @see Character#isWhitespace(int)
*
* @since 11
*/
public String stripLeading() {
String ret = isLatin1() ? StringLatin1.stripLeading(value)
: StringUTF16.stripLeading(value);
return ret == null ? this : ret;
}
/**
* Returns a string whose value is this string, with all trailing
* {@linkplain Character#isWhitespace(int) white space} removed.
* <p>
* If this {@code String} object represents an empty string,
* or if all characters in this string are
* {@linkplain Character#isWhitespace(int) white space}, then an empty string
* is returned.
* <p>
* Otherwise, returns a substring of this string beginning with the first
* code point of this string up to and including the last code point
* that is not a {@linkplain Character#isWhitespace(int) white space}.
* <p>
* This method may be used to trim
* {@linkplain Character#isWhitespace(int) white space} from
* the end of a string.
*
* @return a string whose value is this string, with all trailing white
* space removed
*
* @see Character#isWhitespace(int)
*
* @since 11
*/
public String stripTrailing() {
String ret = isLatin1() ? StringLatin1.stripTrailing(value)
: StringUTF16.stripTrailing(value);
return ret == null ? this : ret;
}
/**
* {@return {@code true} if the string is {@linkplain #isEmpty empty} or contains
* only {@linkplain Character#isWhitespace(int) white space} codepoints,
* otherwise {@code false}}
*
* @see Character#isWhitespace(int)
*
* @since 11
*/
public boolean isBlank() {
return indexOfNonWhitespace() == length();
}
/**
* Returns a stream of lines extracted from this string,
* separated by line terminators.
* <p>
* A <i>line terminator</i> is one of the following:
* a line feed character {@code "\n"} (U+000A),
* a carriage return character {@code "\r"} (U+000D),
* or a carriage return followed immediately by a line feed
* {@code "\r\n"} (U+000D U+000A).
* <p>
* A <i>line</i> is either a sequence of zero or more characters
* followed by a line terminator, or it is a sequence of one or
* more characters followed by the end of the string. A
* line does not include the line terminator.
* <p>
* The stream returned by this method contains the lines from
* this string in the order in which they occur.
*
* @apiNote This definition of <i>line</i> implies that an empty
* string has zero lines and that there is no empty line
* following a line terminator at the end of a string.
*
* @implNote This method provides better performance than
* split("\R") by supplying elements lazily and
* by faster search of new line terminators.
*
* @return the stream of lines extracted from this string
*
* @since 11
*/
public Stream<String> lines() {
return isLatin1() ? StringLatin1.lines(value) : StringUTF16.lines(value);
}
/**
* Adjusts the indentation of each line of this string based on the value of
* {@code n}, and normalizes line termination characters.
* <p>
* This string is conceptually separated into lines using
* {@link String#lines()}. Each line is then adjusted as described below
* and then suffixed with a line feed {@code "\n"} (U+000A). The resulting
* lines are then concatenated and returned.
* <p>
* If {@code n > 0} then {@code n} spaces (U+0020) are inserted at the
* beginning of each line.
* <p>
* If {@code n < 0} then up to {@code n}
* {@linkplain Character#isWhitespace(int) white space characters} are removed
* from the beginning of each line. If a given line does not contain
* sufficient white space then all leading
* {@linkplain Character#isWhitespace(int) white space characters} are removed.
* Each white space character is treated as a single character. In
* particular, the tab character {@code "\t"} (U+0009) is considered a
* single character; it is not expanded.
* <p>
* If {@code n == 0} then the line remains unchanged. However, line
* terminators are still normalized.
*
* @param n number of leading
* {@linkplain Character#isWhitespace(int) white space characters}
* to add or remove
*
* @return string with indentation adjusted and line endings normalized
*
* @see String#lines()
* @see String#isBlank()
* @see Character#isWhitespace(int)
*
* @since 12
*/
public String indent(int n) {
if (isEmpty()) {
return "";
}
Stream<String> stream = lines();
if (n > 0) {
final String spaces = " ".repeat(n);
stream = stream.map(s -> spaces + s);
} else if (n == Integer.MIN_VALUE) {
stream = stream.map(s -> s.stripLeading());
} else if (n < 0) {
stream = stream.map(s -> s.substring(Math.min(-n, s.indexOfNonWhitespace())));
}
return stream.collect(Collectors.joining("\n", "", "\n"));
}
private int indexOfNonWhitespace() {
return isLatin1() ? StringLatin1.indexOfNonWhitespace(value)
: StringUTF16.indexOfNonWhitespace(value);
}
private int lastIndexOfNonWhitespace() {
return isLatin1() ? StringLatin1.lastIndexOfNonWhitespace(value)
: StringUTF16.lastIndexOfNonWhitespace(value);
}
/**
* Returns a string whose value is this string, with incidental
* {@linkplain Character#isWhitespace(int) white space} removed from
* the beginning and end of every line.
* <p>
* Incidental {@linkplain Character#isWhitespace(int) white space}
* is often present in a text block to align the content with the opening
* delimiter. For example, in the following code, dots represent incidental
* {@linkplain Character#isWhitespace(int) white space}:
* <blockquote><pre>
* String html = """
* ..............&lt;html&gt;
* .............. &lt;body&gt;
* .............. &lt;p&gt;Hello, world&lt;/p&gt;
* .............. &lt;/body&gt;
* ..............&lt;/html&gt;
* ..............""";
* </pre></blockquote>
* This method treats the incidental
* {@linkplain Character#isWhitespace(int) white space} as indentation to be
* stripped, producing a string that preserves the relative indentation of
* the content. Using | to visualize the start of each line of the string:
* <blockquote><pre>
* |&lt;html&gt;
* | &lt;body&gt;
* | &lt;p&gt;Hello, world&lt;/p&gt;
* | &lt;/body&gt;
* |&lt;/html&gt;
* </pre></blockquote>
* First, the individual lines of this string are extracted. A <i>line</i>
* is a sequence of zero or more characters followed by either a line
* terminator or the end of the string.
* If the string has at least one line terminator, the last line consists
* of the characters between the last terminator and the end of the string.
* Otherwise, if the string has no terminators, the last line is the start
* of the string to the end of the string, in other words, the entire
* string.
* A line does not include the line terminator.
* <p>
* Then, the <i>minimum indentation</i> (min) is determined as follows:
* <ul>
* <li><p>For each non-blank line (as defined by {@link String#isBlank()}),
* the leading {@linkplain Character#isWhitespace(int) white space}
* characters are counted.</p>
* </li>
* <li><p>The leading {@linkplain Character#isWhitespace(int) white space}
* characters on the last line are also counted even if
* {@linkplain String#isBlank() blank}.</p>
* </li>
* </ul>
* <p>The <i>min</i> value is the smallest of these counts.
* <p>
* For each {@linkplain String#isBlank() non-blank} line, <i>min</i> leading
* {@linkplain Character#isWhitespace(int) white space} characters are
* removed, and any trailing {@linkplain Character#isWhitespace(int) white
* space} characters are removed. {@linkplain String#isBlank() Blank} lines
* are replaced with the empty string.
*
* <p>
* Finally, the lines are joined into a new string, using the LF character
* {@code "\n"} (U+000A) to separate lines.
*
* @apiNote
* This method's primary purpose is to shift a block of lines as far as
* possible to the left, while preserving relative indentation. Lines
* that were indented the least will thus have no leading
* {@linkplain Character#isWhitespace(int) white space}.
* The result will have the same number of line terminators as this string.
* If this string ends with a line terminator then the result will end
* with a line terminator.
*
* @implSpec
* This method treats all {@linkplain Character#isWhitespace(int) white space}
* characters as having equal width. As long as the indentation on every
* line is consistently composed of the same character sequences, then the
* result will be as described above.
*
* @return string with incidental indentation removed and line
* terminators normalized
*
* @see String#lines()
* @see String#isBlank()
* @see String#indent(int)
* @see Character#isWhitespace(int)
*
* @since 15
*
*/
public String stripIndent() {
int length = length();
if (length == 0) {
return "";
}
char lastChar = charAt(length - 1);
boolean optOut = lastChar == '\n' || lastChar == '\r';
List<String> lines = lines().toList();
final int outdent = optOut ? 0 : outdent(lines);
return lines.stream()
.map(line -> {
int firstNonWhitespace = line.indexOfNonWhitespace();
int lastNonWhitespace = line.lastIndexOfNonWhitespace();
int incidentalWhitespace = Math.min(outdent, firstNonWhitespace);
return firstNonWhitespace > lastNonWhitespace
? "" : line.substring(incidentalWhitespace, lastNonWhitespace);
})
.collect(Collectors.joining("\n", "", optOut ? "\n" : ""));
}
private static int outdent(List<String> lines) {
// Note: outdent is guaranteed to be zero or positive number.
// If there isn't a non-blank line then the last must be blank
int outdent = Integer.MAX_VALUE;
for (String line : lines) {
int leadingWhitespace = line.indexOfNonWhitespace();
if (leadingWhitespace != line.length()) {
outdent = Integer.min(outdent, leadingWhitespace);
}
}
String lastLine = lines.get(lines.size() - 1);
if (lastLine.isBlank()) {
outdent = Integer.min(outdent, lastLine.length());
}
return outdent;
}
/**
* Returns a string whose value is this string, with escape sequences
* translated as if in a string literal.
* <p>
* Escape sequences are translated as follows;
* <table class="striped">
* <caption style="display:none">Translation</caption>
* <thead>
* <tr>
* <th scope="col">Escape</th>
* <th scope="col">Name</th>
* <th scope="col">Translation</th>
* </tr>
* </thead>
* <tbody>
* <tr>
* <th scope="row">{@code \u005Cb}</th>
* <td>backspace</td>
* <td>{@code U+0008}</td>
* </tr>
* <tr>
* <th scope="row">{@code \u005Ct}</th>
* <td>horizontal tab</td>
* <td>{@code U+0009}</td>
* </tr>
* <tr>
* <th scope="row">{@code \u005Cn}</th>
* <td>line feed</td>
* <td>{@code U+000A}</td>
* </tr>
* <tr>
* <th scope="row">{@code \u005Cf}</th>
* <td>form feed</td>
* <td>{@code U+000C}</td>
* </tr>
* <tr>
* <th scope="row">{@code \u005Cr}</th>
* <td>carriage return</td>
* <td>{@code U+000D}</td>
* </tr>
* <tr>
* <th scope="row">{@code \u005Cs}</th>
* <td>space</td>
* <td>{@code U+0020}</td>
* </tr>
* <tr>
* <th scope="row">{@code \u005C"}</th>
* <td>double quote</td>
* <td>{@code U+0022}</td>
* </tr>
* <tr>
* <th scope="row">{@code \u005C'}</th>
* <td>single quote</td>
* <td>{@code U+0027}</td>
* </tr>
* <tr>
* <th scope="row">{@code \u005C\u005C}</th>
* <td>backslash</td>
* <td>{@code U+005C}</td>
* </tr>
* <tr>
* <th scope="row">{@code \u005C0 - \u005C377}</th>
* <td>octal escape</td>
* <td>code point equivalents</td>
* </tr>
* <tr>
* <th scope="row">{@code \u005C<line-terminator>}</th>
* <td>continuation</td>
* <td>discard</td>
* </tr>
* </tbody>
* </table>
*
* @implNote
* This method does <em>not</em> translate Unicode escapes such as "{@code \u005cu2022}".
* Unicode escapes are translated by the Java compiler when reading input characters and
* are not part of the string literal specification.
*
* @throws IllegalArgumentException when an escape sequence is malformed.
*
* @return String with escape sequences translated.
*
* @jls 3.10.7 Escape Sequences
*
* @since 15
*/
public String translateEscapes() {
if (isEmpty()) {
return "";
}
char[] chars = toCharArray();
int length = chars.length;
int from = 0;
int to = 0;
while (from < length) {
char ch = chars[from++];
if (ch == '\\') {
ch = from < length ? chars[from++] : '\0';
switch (ch) {
case 'b':
ch = '\b';
break;
case 'f':
ch = '\f';
break;
case 'n':
ch = '\n';
break;
case 'r':
ch = '\r';
break;
case 's':
ch = ' ';
break;
case 't':
ch = '\t';
break;
case '\'':
case '\"':
case '\\':
// as is
break;
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
int limit = Integer.min(from + (ch <= '3' ? 2 : 1), length);
int code = ch - '0';
while (from < limit) {
ch = chars[from];
if (ch < '0' || '7' < ch) {
break;
}
from++;
code = (code << 3) | (ch - '0');
}
ch = (char)code;
break;
case '\n':
continue;
case '\r':
if (from < length && chars[from] == '\n') {
from++;
}
continue;
default: {
String msg = String.format(
"Invalid escape sequence: \\%c \\\\u%04X",
ch, (int)ch);
throw new IllegalArgumentException(msg);
}
}
}
chars[to++] = ch;
}
return new String(chars, 0, to);
}
/**
* This method allows the application of a function to {@code this}
* string. The function should expect a single String argument
* and produce an {@code R} result.
* <p>
* Any exception thrown by {@code f.apply()} will be propagated to the
* caller.
*
* @param f a function to apply
*
* @param <R> the type of the result
*
* @return the result of applying the function to this string
*
* @see java.util.function.Function
*
* @since 12
*/
public <R> R transform(Function<? super String, ? extends R> f) {
return f.apply(this);
}
/**
* This object (which is already a string!) is itself returned.
*
* @return the string itself.
*/
public String toString() {
return this;
}
/**
* Returns a stream of {@code int} zero-extending the {@code char} values
* from this sequence. Any char which maps to a {@linkplain
* Character##unicode surrogate code point} is passed through
* uninterpreted.
*
* @return an IntStream of char values from this sequence
* @since 9
*/
@Override
public IntStream chars() {
return StreamSupport.intStream(
isLatin1() ? new StringLatin1.CharsSpliterator(value, Spliterator.IMMUTABLE)
: new StringUTF16.CharsSpliterator(value, Spliterator.IMMUTABLE),
false);
}
/**
* Returns a stream of code point values from this sequence. Any surrogate
* pairs encountered in the sequence are combined as if by {@linkplain
* Character#toCodePoint Character.toCodePoint} and the result is passed
* to the stream. Any other code units, including ordinary BMP characters,
* unpaired surrogates, and undefined code units, are zero-extended to
* {@code int} values which are then passed to the stream.
*
* @return an IntStream of Unicode code points from this sequence
* @since 9
*/
@Override
public IntStream codePoints() {
return StreamSupport.intStream(
isLatin1() ? new StringLatin1.CharsSpliterator(value, Spliterator.IMMUTABLE)
: new StringUTF16.CodePointsSpliterator(value, Spliterator.IMMUTABLE),
false);
}
/**
* Converts this string to a new character array.
*
* @return a newly allocated character array whose length is the length
* of this string and whose contents are initialized to contain
* the character sequence represented by this string.
*/
public char[] toCharArray() {
return isLatin1() ? StringLatin1.toChars(value)
: StringUTF16.toChars(value);
}
/**
* Returns a formatted string using the specified format string and
* arguments.
*
* <p> The locale always used is the one returned by {@link
* java.util.Locale#getDefault(java.util.Locale.Category)
* Locale.getDefault(Locale.Category)} with
* {@link java.util.Locale.Category#FORMAT FORMAT} category specified.
*
* @param format
* A <a href="../util/Formatter.html#syntax">format string</a>
*
* @param args
* Arguments referenced by the format specifiers in the format
* string. If there are more arguments than format specifiers, the
* extra arguments are ignored. The number of arguments is
* variable and may be zero. The maximum number of arguments is
* limited by the maximum dimension of a Java array as defined by
* <cite>The Java Virtual Machine Specification</cite>.
* The behaviour on a
* {@code null} argument depends on the <a
* href="../util/Formatter.html#syntax">conversion</a>.
*
* @throws java.util.IllegalFormatException
* If a format string contains an illegal syntax, a format
* specifier that is incompatible with the given arguments,
* insufficient arguments given the format string, or other
* illegal conditions. For specification of all possible
* formatting errors, see the <a
* href="../util/Formatter.html#detail">Details</a> section of the
* formatter class specification.
*
* @return A formatted string
*
* @see java.util.Formatter
* @since 1.5
*/
public static String format(String format, Object... args) {
return new Formatter().format(format, args).toString();
}
/**
* Returns a formatted string using the specified locale, format string,
* and arguments.
*
* @param l
* The {@linkplain java.util.Locale locale} to apply during
* formatting. If {@code l} is {@code null} then no localization
* is applied.
*
* @param format
* A <a href="../util/Formatter.html#syntax">format string</a>
*
* @param args
* Arguments referenced by the format specifiers in the format
* string. If there are more arguments than format specifiers, the
* extra arguments are ignored. The number of arguments is
* variable and may be zero. The maximum number of arguments is
* limited by the maximum dimension of a Java array as defined by
* <cite>The Java Virtual Machine Specification</cite>.
* The behaviour on a
* {@code null} argument depends on the
* <a href="../util/Formatter.html#syntax">conversion</a>.
*
* @throws java.util.IllegalFormatException
* If a format string contains an illegal syntax, a format
* specifier that is incompatible with the given arguments,
* insufficient arguments given the format string, or other
* illegal conditions. For specification of all possible
* formatting errors, see the <a
* href="../util/Formatter.html#detail">Details</a> section of the
* formatter class specification
*
* @return A formatted string
*
* @see java.util.Formatter
* @since 1.5
*/
public static String format(Locale l, String format, Object... args) {
return new Formatter(l).format(format, args).toString();
}
/**
* Formats using this string as the format string, and the supplied
* arguments.
*
* @implSpec This method is equivalent to {@code String.format(this, args)}.
*
* @param args
* Arguments referenced by the format specifiers in this string.
*
* @return A formatted string
*
* @see java.lang.String#format(String,Object...)
* @see java.util.Formatter
*
* @since 15
*
*/
public String formatted(Object... args) {
return new Formatter().format(this, args).toString();
}
/**
* Returns the string representation of the {@code Object} argument.
*
* @param obj an {@code Object}.
* @return if the argument is {@code null}, then a string equal to
* {@code "null"}; otherwise, the value of
* {@code obj.toString()} is returned.
* @see java.lang.Object#toString()
*/
public static String valueOf(Object obj) {
return (obj == null) ? "null" : obj.toString();
}
/**
* Returns the string representation of the {@code char} array
* argument. The contents of the character array are copied; subsequent
* modification of the character array does not affect the returned
* string.
*
* <p> The contents of the string are unspecified if the character array
* is modified during string construction.
*
* @param data the character array.
* @return a {@code String} that contains the characters of the
* character array.
*/
public static String valueOf(char[] data) {
return new String(data);
}
/**
* Returns the string representation of a specific subarray of the
* {@code char} array argument.
* <p>
* The {@code offset} argument is the index of the first
* character of the subarray. The {@code count} argument
* specifies the length of the subarray. The contents of the subarray
* are copied; subsequent modification of the character array does not
* affect the returned string.
*
* <p> The contents of the string are unspecified if the character array
* is modified during string construction.
*
* @param data the character array.
* @param offset initial offset of the subarray.
* @param count length of the subarray.
* @return a {@code String} that contains the characters of the
* specified subarray of the character array.
* @throws IndexOutOfBoundsException if {@code offset} is
* negative, or {@code count} is negative, or
* {@code offset+count} is larger than
* {@code data.length}.
*/
public static String valueOf(char[] data, int offset, int count) {
return new String(data, offset, count);
}
/**
* Equivalent to {@link #valueOf(char[], int, int)}.
*
* @param data the character array.
* @param offset initial offset of the subarray.
* @param count length of the subarray.
* @return a {@code String} that contains the characters of the
* specified subarray of the character array.
* @throws IndexOutOfBoundsException if {@code offset} is
* negative, or {@code count} is negative, or
* {@code offset+count} is larger than
* {@code data.length}.
*/
public static String copyValueOf(char[] data, int offset, int count) {
return new String(data, offset, count);
}
/**
* Equivalent to {@link #valueOf(char[])}.
*
* @param data the character array.
* @return a {@code String} that contains the characters of the
* character array.
*/
public static String copyValueOf(char[] data) {
return new String(data);
}
/**
* Returns the string representation of the {@code boolean} argument.
*
* @param b a {@code boolean}.
* @return if the argument is {@code true}, a string equal to
* {@code "true"} is returned; otherwise, a string equal to
* {@code "false"} is returned.
*/
public static String valueOf(boolean b) {
return b ? "true" : "false";
}
/**
* Returns the string representation of the {@code char}
* argument.
*
* @param c a {@code char}.
* @return a string of length {@code 1} containing
* as its single character the argument {@code c}.
*/
public static String valueOf(char c) {
if (COMPACT_STRINGS && StringLatin1.canEncode(c)) {
return new String(StringLatin1.toBytes(c), LATIN1);
}
return new String(StringUTF16.toBytes(c), UTF16);
}
/**
* Returns the string representation of the {@code int} argument.
* <p>
* The representation is exactly the one returned by the
* {@code Integer.toString} method of one argument.
*
* @param i an {@code int}.
* @return a string representation of the {@code int} argument.
* @see java.lang.Integer#toString(int, int)
*/
public static String valueOf(int i) {
return Integer.toString(i);
}
/**
* Returns the string representation of the {@code long} argument.
* <p>
* The representation is exactly the one returned by the
* {@code Long.toString} method of one argument.
*
* @param l a {@code long}.
* @return a string representation of the {@code long} argument.
* @see java.lang.Long#toString(long)
*/
public static String valueOf(long l) {
return Long.toString(l);
}
/**
* Returns the string representation of the {@code float} argument.
* <p>
* The representation is exactly the one returned by the
* {@code Float.toString} method of one argument.
*
* @param f a {@code float}.
* @return a string representation of the {@code float} argument.
* @see java.lang.Float#toString(float)
*/
public static String valueOf(float f) {
return Float.toString(f);
}
/**
* Returns the string representation of the {@code double} argument.
* <p>
* The representation is exactly the one returned by the
* {@code Double.toString} method of one argument.
*
* @param d a {@code double}.
* @return a string representation of the {@code double} argument.
* @see java.lang.Double#toString(double)
*/
public static String valueOf(double d) {
return Double.toString(d);
}
/**
* Returns a canonical representation for the string object.
* <p>
* A pool of strings, initially empty, is maintained privately by the
* class {@code String}.
* <p>
* When the intern method is invoked, if the pool already contains a
* string equal to this {@code String} object as determined by
* the {@link #equals(Object)} method, then the string from the pool is
* returned. Otherwise, this {@code String} object is added to the
* pool and a reference to this {@code String} object is returned.
* <p>
* It follows that for any two strings {@code s} and {@code t},
* {@code s.intern() == t.intern()} is {@code true}
* if and only if {@code s.equals(t)} is {@code true}.
* <p>
* All literal strings and string-valued constant expressions are
* interned. String literals are defined in section {@jls 3.10.5} of the
* <cite>The Java Language Specification</cite>.
*
* @return a string that has the same contents as this string, but is
* guaranteed to be from a pool of unique strings.
*/
public native String intern();
/**
* Returns a string whose value is the concatenation of this
* string repeated {@code count} times.
* <p>
* If this string is empty or count is zero then the empty
* string is returned.
*
* @param count number of times to repeat
*
* @return A string composed of this string repeated
* {@code count} times or the empty string if this
* string is empty or count is zero
*
* @throws IllegalArgumentException if the {@code count} is
* negative.
*
* @since 11
*/
public String repeat(int count) {
if (count < 0) {
throw new IllegalArgumentException("count is negative: " + count);
}
if (count == 1) {
return this;
}
final int len = value.length;
if (len == 0 || count == 0) {
return "";
}
if (Integer.MAX_VALUE / count < len) {
throw new OutOfMemoryError("Required length exceeds implementation limit");
}
if (len == 1) {
final byte[] single = new byte[count];
Arrays.fill(single, value[0]);
return new String(single, coder);
}
final int limit = len * count;
final byte[] multiple = new byte[limit];
System.arraycopy(value, 0, multiple, 0, len);
repeatCopyRest(multiple, 0, limit, len);
return new String(multiple, coder);
}
/**
* Used to perform copying after the initial insertion. Copying is optimized
* by using power of two duplication. First pass duplicates original copy,
* second pass then duplicates the original and the copy yielding four copies,
* third pass duplicates four copies yielding eight copies, and so on.
* Finally, the remainder is filled in with prior copies.
*
* @implNote The technique used here is significantly faster than hand-rolled
* loops or special casing small numbers due to the intensive optimization
* done by intrinsic {@code System.arraycopy}.
*
* @param buffer destination buffer
* @param offset offset in the destination buffer
* @param limit total replicated including what is already in the buffer
* @param copied number of bytes that have already in the buffer
*/
static void repeatCopyRest(byte[] buffer, int offset, int limit, int copied) {
// Initial copy is in the buffer.
for (; copied < limit - copied; copied <<= 1) {
// Power of two duplicate.
System.arraycopy(buffer, offset, buffer, offset + copied, copied);
}
// Duplicate remainder.
System.arraycopy(buffer, offset, buffer, offset + copied, limit - copied);
}
//--------------------------------------------------------------
/**
* Copy character bytes from this string into dst starting at dstBegin.
* This method doesn't perform any range checking.
*
* Invoker guarantees: dst is in UTF16 (inflate itself for asb), if two
* coders are different, and dst is big enough (range check)
*
* @param dstBegin the char index, not offset of byte[]
* @param coder the coder of dst[]
*/
void getBytes(byte[] dst, int dstBegin, byte coder) {
if (coder() == coder) {
System.arraycopy(value, 0, dst, dstBegin << coder, value.length);
} else { // this.coder == LATIN && coder == UTF16
StringLatin1.inflate(value, 0, dst, dstBegin, value.length);
}
}
/**
* Copy character bytes from this string into dst starting at dstBegin.
* This method doesn't perform any range checking.
*
* Invoker guarantees: dst is in UTF16 (inflate itself for asb), if two
* coders are different, and dst is big enough (range check)
*
* @param srcPos the char index, not offset of byte[]
* @param dstBegin the char index to start from
* @param coder the coder of dst[]
* @param length the amount of copied chars
*/
void getBytes(byte[] dst, int srcPos, int dstBegin, byte coder, int length) {
if (coder() == coder) {
System.arraycopy(value, srcPos << coder, dst, dstBegin << coder, length << coder);
} else { // this.coder == LATIN && coder == UTF16
StringLatin1.inflate(value, srcPos, dst, dstBegin, length);
}
}
/*
* Private constructor. Trailing Void argument is there for
* disambiguating it against other (public) constructors.
*
* Stores the char[] value into a byte[] that each byte represents
* the8 low-order bits of the corresponding character, if the char[]
* contains only latin1 character. Or a byte[] that stores all
* characters in their byte sequences defined by the {@code StringUTF16}.
*
* <p> The contents of the string are unspecified if the character array
* is modified during string construction.
*/
private String(char[] value, int off, int len, Void sig) {
if (len == 0) {
this.value = "".value;
this.coder = "".coder;
return;
}
if (COMPACT_STRINGS) {
byte[] val = StringUTF16.compress(value, off, len);
this.coder = StringUTF16.coderFromArrayLen(val, len);
this.value = val;
return;
}
this.coder = UTF16;
this.value = StringUTF16.toBytes(value, off, len);
}
/*
* Package private constructor. Trailing Void argument is there for
* disambiguating it against other (public) constructors.
*
* <p> The contents of the string are unspecified if the {@code StringBuilder}
* is modified during string construction.
*/
String(AbstractStringBuilder asb, Void sig) {
byte[] val = asb.getValue();
int length = asb.length();
if (asb.isLatin1()) {
this.coder = LATIN1;
this.value = Arrays.copyOfRange(val, 0, length);
} else {
// only try to compress val if some characters were deleted.
if (COMPACT_STRINGS && asb.maybeLatin1) {
this.value = StringUTF16.compress(val, 0, length);
this.coder = StringUTF16.coderFromArrayLen(this.value, length);
return;
}
this.coder = UTF16;
this.value = Arrays.copyOfRange(val, 0, length << 1);
}
}
/*
* Package private constructor which shares value array for speed.
*/
String(byte[] value, byte coder) {
this.value = value;
this.coder = coder;
}
byte coder() {
return COMPACT_STRINGS ? coder : UTF16;
}
byte[] value() {
return value;
}
boolean isLatin1() {
return COMPACT_STRINGS && coder == LATIN1;
}
@Native static final byte LATIN1 = 0;
@Native static final byte UTF16 = 1;
/*
* StringIndexOutOfBoundsException if {@code index} is
* negative or greater than or equal to {@code length}.
*/
static void checkIndex(int index, int length) {
Preconditions.checkIndex(index, length, Preconditions.SIOOBE_FORMATTER);
}
/*
* StringIndexOutOfBoundsException if {@code offset}
* is negative or greater than {@code length}.
*/
static void checkOffset(int offset, int length) {
Preconditions.checkFromToIndex(offset, length, length, Preconditions.SIOOBE_FORMATTER);
}
/*
* Check {@code offset}, {@code count} against {@code 0} and {@code length}
* bounds.
*
* @return {@code offset} if the sub-range within bounds of the range
* @throws StringIndexOutOfBoundsException
* If {@code offset} is negative, {@code count} is negative,
* or {@code offset} is greater than {@code length - count}
*/
static int checkBoundsOffCount(int offset, int count, int length) {
return Preconditions.checkFromIndexSize(offset, count, length, Preconditions.SIOOBE_FORMATTER);
}
/*
* Check {@code begin}, {@code end} against {@code 0} and {@code length}
* bounds.
*
* @throws StringIndexOutOfBoundsException
* If {@code begin} is negative, {@code begin} is greater than
* {@code end}, or {@code end} is greater than {@code length}.
*/
static void checkBoundsBeginEnd(int begin, int end, int length) {
Preconditions.checkFromToIndex(begin, end, length, Preconditions.SIOOBE_FORMATTER);
}
/**
* Returns the string representation of the {@code codePoint}
* argument.
*
* @param codePoint a {@code codePoint}.
* @return a string of length {@code 1} or {@code 2} containing
* as its single character the argument {@code codePoint}.
* @throws IllegalArgumentException if the specified
* {@code codePoint} is not a {@linkplain Character#isValidCodePoint
* valid Unicode code point}.
*/
static String valueOfCodePoint(int codePoint) {
if (COMPACT_STRINGS && StringLatin1.canEncode(codePoint)) {
return new String(StringLatin1.toBytes((char)codePoint), LATIN1);
} else if (Character.isBmpCodePoint(codePoint)) {
return new String(StringUTF16.toBytes((char)codePoint), UTF16);
} else if (Character.isSupplementaryCodePoint(codePoint)) {
return new String(StringUTF16.toBytesSupplementary(codePoint), UTF16);
}
throw new IllegalArgumentException(
format("Not a valid Unicode code point: 0x%X", codePoint));
}
/**
* Returns an {@link Optional} containing the nominal descriptor for this
* instance, which is the instance itself.
*
* @return an {@link Optional} describing the {@linkplain String} instance
* @since 12
*/
@Override
public Optional<String> describeConstable() {
return Optional.of(this);
}
/**
* Resolves this instance as a {@link ConstantDesc}, the result of which is
* the instance itself.
*
* @param lookup ignored
* @return the {@linkplain String} instance
* @since 12
*/
@Override
public String resolveConstantDesc(MethodHandles.Lookup lookup) {
return this;
}
}