| /* | |
| * Copyright (c) 2003, 2013, 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 | |
| * questions. | |
| */ | |
| package java.util; | |
| import java.io.IOException; | |
| /** | |
| * The {@code Formattable} interface must be implemented by any class that | |
| * needs to perform custom formatting using the {@code 's'} conversion | |
| * specifier of {@link java.util.Formatter}. This interface allows basic | |
| * control for formatting arbitrary objects. | |
| * | |
| * For example, the following class prints out different representations of a | |
| * stock's name depending on the flags and length constraints: | |
| * | |
| * <pre> {@code | |
| * import java.nio.CharBuffer; | |
| * import java.util.Formatter; | |
| * import java.util.Formattable; | |
| * import java.util.Locale; | |
| * import static java.util.FormattableFlags.*; | |
| * | |
| * ... | |
| * | |
| * public class StockName implements Formattable { | |
| * private String symbol, companyName, frenchCompanyName; | |
| * public StockName(String symbol, String companyName, | |
| * String frenchCompanyName) { | |
| * ... | |
| * } | |
| * | |
| * ... | |
| * | |
| * public void formatTo(Formatter fmt, int f, int width, int precision) { | |
| * StringBuilder sb = new StringBuilder(); | |
| * | |
| * // decide form of name | |
| * String name = companyName; | |
| * if (fmt.locale().equals(Locale.FRANCE)) | |
| * name = frenchCompanyName; | |
| * boolean alternate = (f & ALTERNATE) == ALTERNATE; | |
| * boolean usesymbol = alternate || (precision != -1 && precision < 10); | |
| * String out = (usesymbol ? symbol : name); | |
| * | |
| * // apply precision | |
| * if (precision == -1 || out.length() < precision) { | |
| * // write it all | |
| * sb.append(out); | |
| * } else { | |
| * sb.append(out.substring(0, precision - 1)).append('*'); | |
| * } | |
| * | |
| * // apply width and justification | |
| * int len = sb.length(); | |
| * if (len < width) | |
| * for (int i = 0; i < width - len; i++) | |
| * if ((f & LEFT_JUSTIFY) == LEFT_JUSTIFY) | |
| * sb.append(' '); | |
| * else | |
| * sb.insert(0, ' '); | |
| * | |
| * fmt.format(sb.toString()); | |
| * } | |
| * | |
| * public String toString() { | |
| * return String.format("%s - %s", symbol, companyName); | |
| * } | |
| * } | |
| * }</pre> | |
| * | |
| * <p> When used in conjunction with the {@link java.util.Formatter}, the above | |
| * class produces the following output for various format strings. | |
| * | |
| * <pre> {@code | |
| * Formatter fmt = new Formatter(); | |
| * StockName sn = new StockName("HUGE", "Huge Fruit, Inc.", | |
| * "Fruit Titanesque, Inc."); | |
| * fmt.format("%s", sn); // -> "Huge Fruit, Inc." | |
| * fmt.format("%s", sn.toString()); // -> "HUGE - Huge Fruit, Inc." | |
| * fmt.format("%#s", sn); // -> "HUGE" | |
| * fmt.format("%-10.8s", sn); // -> "HUGE " | |
| * fmt.format("%.12s", sn); // -> "Huge Fruit,*" | |
| * fmt.format(Locale.FRANCE, "%25s", sn); // -> " Fruit Titanesque, Inc." | |
| * }</pre> | |
| * | |
| * <p> Formattables are not necessarily safe for multithreaded access. Thread | |
| * safety is optional and may be enforced by classes that extend and implement | |
| * this interface. | |
| * | |
| * <p> Unless otherwise specified, passing a {@code null} argument to | |
| * any method in this interface will cause a {@link | |
| * NullPointerException} to be thrown. | |
| * | |
| * @since 1.5 | |
| */ | |
| public interface Formattable { | |
| /** | |
| * Formats the object using the provided {@link Formatter formatter}. | |
| * | |
| * @param formatter | |
| * The {@link Formatter formatter}. Implementing classes may call | |
| * {@link Formatter#out() formatter.out()} or {@link | |
| * Formatter#locale() formatter.locale()} to obtain the {@link | |
| * Appendable} or {@link Locale} used by this | |
| * {@code formatter} respectively. | |
| * | |
| * @param flags | |
| * The flags modify the output format. The value is interpreted as | |
| * a bitmask. Any combination of the following flags may be set: | |
| * {@link FormattableFlags#LEFT_JUSTIFY}, {@link | |
| * FormattableFlags#UPPERCASE}, and {@link | |
| * FormattableFlags#ALTERNATE}. If no flags are set, the default | |
| * formatting of the implementing class will apply. | |
| * | |
| * @param width | |
| * The minimum number of characters to be written to the output. | |
| * If the length of the converted value is less than the | |
| * {@code width} then the output will be padded by | |
| * <code>' '</code> until the total number of characters | |
| * equals width. The padding is at the beginning by default. If | |
| * the {@link FormattableFlags#LEFT_JUSTIFY} flag is set then the | |
| * padding will be at the end. If {@code width} is {@code -1} | |
| * then there is no minimum. | |
| * | |
| * @param precision | |
| * The maximum number of characters to be written to the output. | |
| * The precision is applied before the width, thus the output will | |
| * be truncated to {@code precision} characters even if the | |
| * {@code width} is greater than the {@code precision}. If | |
| * {@code precision} is {@code -1} then there is no explicit | |
| * limit on the number of characters. | |
| * | |
| * @throws IllegalFormatException | |
| * If any of the parameters are invalid. For specification of all | |
| * possible formatting errors, see the <a | |
| * href="../util/Formatter.html#detail">Details</a> section of the | |
| * formatter class specification. | |
| */ | |
| void formatTo(Formatter formatter, int flags, int width, int precision); | |
| } |