| /* | |
| * Copyright (c) 1997, 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 | |
| * questions. | |
| */ | |
| package java.util; | |
| import java.util.stream.Stream; | |
| import java.util.function.Consumer; | |
| import java.util.function.IntFunction; | |
| import java.util.function.Predicate; | |
| /** | |
| * This class provides a skeletal implementation of the {@code Map} | |
| * interface, to minimize the effort required to implement this interface. | |
| * | |
| * <p>To implement an unmodifiable map, the programmer needs only to extend this | |
| * class and provide an implementation for the {@code entrySet} method, which | |
| * returns a set-view of the map's mappings. Typically, the returned set | |
| * will, in turn, be implemented atop {@code AbstractSet}. This set should | |
| * not support the {@code add} or {@code remove} methods, and its iterator | |
| * should not support the {@code remove} method. | |
| * | |
| * <p>To implement a modifiable map, the programmer must additionally override | |
| * this class's {@code put} method (which otherwise throws an | |
| * {@code UnsupportedOperationException}), and the iterator returned by | |
| * {@code entrySet().iterator()} must additionally implement its | |
| * {@code remove} method. | |
| * | |
| * <p>The programmer should generally provide a void (no argument) and map | |
| * constructor, as per the recommendation in the {@code Map} interface | |
| * specification. | |
| * | |
| * <p>The documentation for each non-abstract method in this class describes its | |
| * implementation in detail. Each of these methods may be overridden if the | |
| * map being implemented admits a more efficient implementation. | |
| * | |
| * <p>This class is a member of the | |
| * <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework"> | |
| * Java Collections Framework</a>. | |
| * | |
| * @param <K> the type of keys maintained by this map | |
| * @param <V> the type of mapped values | |
| * | |
| * @author Josh Bloch | |
| * @author Neal Gafter | |
| * @see Map | |
| * @see Collection | |
| * @since 1.2 | |
| */ | |
| public abstract class AbstractMap<K,V> implements Map<K,V> { | |
| /** | |
| * Sole constructor. (For invocation by subclass constructors, typically | |
| * implicit.) | |
| */ | |
| protected AbstractMap() { | |
| } | |
| // Query Operations | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation returns {@code entrySet().size()}. | |
| */ | |
| public int size() { | |
| return entrySet().size(); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation returns {@code size() == 0}. | |
| */ | |
| public boolean isEmpty() { | |
| return size() == 0; | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation iterates over {@code entrySet()} searching | |
| * for an entry with the specified value. If such an entry is found, | |
| * {@code true} is returned. If the iteration terminates without | |
| * finding such an entry, {@code false} is returned. Note that this | |
| * implementation requires linear time in the size of the map. | |
| * | |
| * @throws ClassCastException {@inheritDoc} | |
| * @throws NullPointerException {@inheritDoc} | |
| */ | |
| public boolean containsValue(Object value) { | |
| Iterator<Entry<K,V>> i = entrySet().iterator(); | |
| if (value==null) { | |
| while (i.hasNext()) { | |
| Entry<K,V> e = i.next(); | |
| if (e.getValue()==null) | |
| return true; | |
| } | |
| } else { | |
| while (i.hasNext()) { | |
| Entry<K,V> e = i.next(); | |
| if (value.equals(e.getValue())) | |
| return true; | |
| } | |
| } | |
| return false; | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation iterates over {@code entrySet()} searching | |
| * for an entry with the specified key. If such an entry is found, | |
| * {@code true} is returned. If the iteration terminates without | |
| * finding such an entry, {@code false} is returned. Note that this | |
| * implementation requires linear time in the size of the map; many | |
| * implementations will override this method. | |
| * | |
| * @throws ClassCastException {@inheritDoc} | |
| * @throws NullPointerException {@inheritDoc} | |
| */ | |
| public boolean containsKey(Object key) { | |
| Iterator<Map.Entry<K,V>> i = entrySet().iterator(); | |
| if (key==null) { | |
| while (i.hasNext()) { | |
| Entry<K,V> e = i.next(); | |
| if (e.getKey()==null) | |
| return true; | |
| } | |
| } else { | |
| while (i.hasNext()) { | |
| Entry<K,V> e = i.next(); | |
| if (key.equals(e.getKey())) | |
| return true; | |
| } | |
| } | |
| return false; | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation iterates over {@code entrySet()} searching | |
| * for an entry with the specified key. If such an entry is found, | |
| * the entry's value is returned. If the iteration terminates without | |
| * finding such an entry, {@code null} is returned. Note that this | |
| * implementation requires linear time in the size of the map; many | |
| * implementations will override this method. | |
| * | |
| * @throws ClassCastException {@inheritDoc} | |
| * @throws NullPointerException {@inheritDoc} | |
| */ | |
| public V get(Object key) { | |
| Iterator<Entry<K,V>> i = entrySet().iterator(); | |
| if (key==null) { | |
| while (i.hasNext()) { | |
| Entry<K,V> e = i.next(); | |
| if (e.getKey()==null) | |
| return e.getValue(); | |
| } | |
| } else { | |
| while (i.hasNext()) { | |
| Entry<K,V> e = i.next(); | |
| if (key.equals(e.getKey())) | |
| return e.getValue(); | |
| } | |
| } | |
| return null; | |
| } | |
| // Modification Operations | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation always throws an | |
| * {@code UnsupportedOperationException}. | |
| * | |
| * @throws UnsupportedOperationException {@inheritDoc} | |
| * @throws ClassCastException {@inheritDoc} | |
| * @throws NullPointerException {@inheritDoc} | |
| * @throws IllegalArgumentException {@inheritDoc} | |
| */ | |
| public V put(K key, V value) { | |
| throw new UnsupportedOperationException(); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation iterates over {@code entrySet()} searching for an | |
| * entry with the specified key. If such an entry is found, its value is | |
| * obtained with its {@code getValue} operation, the entry is removed | |
| * from the collection (and the backing map) with the iterator's | |
| * {@code remove} operation, and the saved value is returned. If the | |
| * iteration terminates without finding such an entry, {@code null} is | |
| * returned. Note that this implementation requires linear time in the | |
| * size of the map; many implementations will override this method. | |
| * | |
| * <p>Note that this implementation throws an | |
| * {@code UnsupportedOperationException} if the {@code entrySet} | |
| * iterator does not support the {@code remove} method and this map | |
| * contains a mapping for the specified key. | |
| * | |
| * @throws UnsupportedOperationException {@inheritDoc} | |
| * @throws ClassCastException {@inheritDoc} | |
| * @throws NullPointerException {@inheritDoc} | |
| */ | |
| public V remove(Object key) { | |
| Iterator<Entry<K,V>> i = entrySet().iterator(); | |
| Entry<K,V> correctEntry = null; | |
| if (key==null) { | |
| while (correctEntry==null && i.hasNext()) { | |
| Entry<K,V> e = i.next(); | |
| if (e.getKey()==null) | |
| correctEntry = e; | |
| } | |
| } else { | |
| while (correctEntry==null && i.hasNext()) { | |
| Entry<K,V> e = i.next(); | |
| if (key.equals(e.getKey())) | |
| correctEntry = e; | |
| } | |
| } | |
| V oldValue = null; | |
| if (correctEntry !=null) { | |
| oldValue = correctEntry.getValue(); | |
| i.remove(); | |
| } | |
| return oldValue; | |
| } | |
| // Bulk Operations | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation iterates over the specified map's | |
| * {@code entrySet()} collection, and calls this map's {@code put} | |
| * operation once for each entry returned by the iteration. | |
| * | |
| * <p>Note that this implementation throws an | |
| * {@code UnsupportedOperationException} if this map does not support | |
| * the {@code put} operation and the specified map is nonempty. | |
| * | |
| * @throws UnsupportedOperationException {@inheritDoc} | |
| * @throws ClassCastException {@inheritDoc} | |
| * @throws NullPointerException {@inheritDoc} | |
| * @throws IllegalArgumentException {@inheritDoc} | |
| */ | |
| public void putAll(Map<? extends K, ? extends V> m) { | |
| for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) | |
| put(e.getKey(), e.getValue()); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation calls {@code entrySet().clear()}. | |
| * | |
| * <p>Note that this implementation throws an | |
| * {@code UnsupportedOperationException} if the {@code entrySet} | |
| * does not support the {@code clear} operation. | |
| * | |
| * @throws UnsupportedOperationException {@inheritDoc} | |
| */ | |
| public void clear() { | |
| entrySet().clear(); | |
| } | |
| // Views | |
| /** | |
| * Each of these fields are initialized to contain an instance of the | |
| * appropriate view the first time this view is requested. The views are | |
| * stateless, so there's no reason to create more than one of each. | |
| * | |
| * <p>Since there is no synchronization performed while accessing these fields, | |
| * it is expected that java.util.Map view classes using these fields have | |
| * no non-final fields (or any fields at all except for outer-this). Adhering | |
| * to this rule would make the races on these fields benign. | |
| * | |
| * <p>It is also imperative that implementations read the field only once, | |
| * as in: | |
| * | |
| * <pre> {@code | |
| * public Set<K> keySet() { | |
| * Set<K> ks = keySet; // single racy read | |
| * if (ks == null) { | |
| * ks = new KeySet(); | |
| * keySet = ks; | |
| * } | |
| * return ks; | |
| * } | |
| *}</pre> | |
| */ | |
| transient Set<K> keySet; | |
| transient Collection<V> values; | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation returns a set that subclasses {@link AbstractSet}. | |
| * The subclass's iterator method returns a "wrapper object" over this | |
| * map's {@code entrySet()} iterator. The {@code size} method | |
| * delegates to this map's {@code size} method and the | |
| * {@code contains} method delegates to this map's | |
| * {@code containsKey} method. | |
| * | |
| * <p>The set is created the first time this method is called, | |
| * and returned in response to all subsequent calls. No synchronization | |
| * is performed, so there is a slight chance that multiple calls to this | |
| * method will not all return the same set. | |
| */ | |
| public Set<K> keySet() { | |
| Set<K> ks = keySet; | |
| if (ks == null) { | |
| ks = new AbstractSet<>() { | |
| public Iterator<K> iterator() { | |
| return new KeyIterator(); | |
| } | |
| public int size() { | |
| return AbstractMap.this.size(); | |
| } | |
| public boolean isEmpty() { | |
| return AbstractMap.this.isEmpty(); | |
| } | |
| public void clear() { | |
| AbstractMap.this.clear(); | |
| } | |
| public boolean contains(Object k) { | |
| return AbstractMap.this.containsKey(k); | |
| } | |
| }; | |
| keySet = ks; | |
| } | |
| return ks; | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * | |
| * @implSpec | |
| * This implementation returns a collection that subclasses {@link | |
| * AbstractCollection}. The subclass's iterator method returns a | |
| * "wrapper object" over this map's {@code entrySet()} iterator. | |
| * The {@code size} method delegates to this map's {@code size} | |
| * method and the {@code contains} method delegates to this map's | |
| * {@code containsValue} method. | |
| * | |
| * <p>The collection is created the first time this method is called, and | |
| * returned in response to all subsequent calls. No synchronization is | |
| * performed, so there is a slight chance that multiple calls to this | |
| * method will not all return the same collection. | |
| */ | |
| public Collection<V> values() { | |
| Collection<V> vals = values; | |
| if (vals == null) { | |
| vals = new AbstractCollection<>() { | |
| public Iterator<V> iterator() { | |
| return new ValueIterator(); | |
| } | |
| public int size() { | |
| return AbstractMap.this.size(); | |
| } | |
| public boolean isEmpty() { | |
| return AbstractMap.this.isEmpty(); | |
| } | |
| public void clear() { | |
| AbstractMap.this.clear(); | |
| } | |
| public boolean contains(Object v) { | |
| return AbstractMap.this.containsValue(v); | |
| } | |
| }; | |
| values = vals; | |
| } | |
| return vals; | |
| } | |
| public abstract Set<Entry<K,V>> entrySet(); | |
| // Comparison and hashing | |
| /** | |
| * Compares the specified object with this map for equality. Returns | |
| * {@code true} if the given object is also a map and the two maps | |
| * represent the same mappings. More formally, two maps {@code m1} and | |
| * {@code m2} represent the same mappings if | |
| * {@code m1.entrySet().equals(m2.entrySet())}. This ensures that the | |
| * {@code equals} method works properly across different implementations | |
| * of the {@code Map} interface. | |
| * | |
| * @implSpec | |
| * This implementation first checks if the specified object is this map; | |
| * if so it returns {@code true}. Then, it checks if the specified | |
| * object is a map whose size is identical to the size of this map; if | |
| * not, it returns {@code false}. If so, it iterates over this map's | |
| * {@code entrySet} collection, and checks that the specified map | |
| * contains each mapping that this map contains. If the specified map | |
| * fails to contain such a mapping, {@code false} is returned. If the | |
| * iteration completes, {@code true} is returned. | |
| * | |
| * @param o object to be compared for equality with this map | |
| * @return {@code true} if the specified object is equal to this map | |
| */ | |
| public boolean equals(Object o) { | |
| if (o == this) | |
| return true; | |
| if (!(o instanceof Map<?, ?> m)) | |
| return false; | |
| if (m.size() != size()) | |
| return false; | |
| try { | |
| for (Entry<K, V> e : entrySet()) { | |
| K key = e.getKey(); | |
| V value = e.getValue(); | |
| if (value == null) { | |
| if (!(m.get(key) == null && m.containsKey(key))) | |
| return false; | |
| } else { | |
| if (!value.equals(m.get(key))) | |
| return false; | |
| } | |
| } | |
| } catch (ClassCastException | NullPointerException unused) { | |
| return false; | |
| } | |
| return true; | |
| } | |
| /** | |
| * Returns the hash code value for this map. The hash code of a map is | |
| * defined to be the sum of the hash codes of each entry in the map's | |
| * {@code entrySet()} view. This ensures that {@code m1.equals(m2)} | |
| * implies that {@code m1.hashCode()==m2.hashCode()} for any two maps | |
| * {@code m1} and {@code m2}, as required by the general contract of | |
| * {@link Object#hashCode}. | |
| * | |
| * @implSpec | |
| * This implementation iterates over {@code entrySet()}, calling | |
| * {@link Map.Entry#hashCode hashCode()} on each element (entry) in the | |
| * set, and adding up the results. | |
| * | |
| * @return the hash code value for this map | |
| * @see Map.Entry#hashCode() | |
| * @see Object#equals(Object) | |
| * @see Set#equals(Object) | |
| */ | |
| public int hashCode() { | |
| int h = 0; | |
| for (Entry<K, V> entry : entrySet()) | |
| h += entry.hashCode(); | |
| return h; | |
| } | |
| /** | |
| * Returns a string representation of this map. The string representation | |
| * consists of a list of key-value mappings in the order returned by the | |
| * map's {@code entrySet} view's iterator, enclosed in braces | |
| * ({@code "{}"}). Adjacent mappings are separated by the characters | |
| * {@code ", "} (comma and space). Each key-value mapping is rendered as | |
| * the key followed by an equals sign ({@code "="}) followed by the | |
| * associated value. Keys and values are converted to strings as by | |
| * {@link String#valueOf(Object)}. | |
| * | |
| * @return a string representation of this map | |
| */ | |
| public String toString() { | |
| Iterator<Entry<K,V>> i = entrySet().iterator(); | |
| if (! i.hasNext()) | |
| return "{}"; | |
| StringBuilder sb = new StringBuilder(); | |
| sb.append('{'); | |
| for (;;) { | |
| Entry<K,V> e = i.next(); | |
| K key = e.getKey(); | |
| V value = e.getValue(); | |
| sb.append(key == this ? "(this Map)" : key); | |
| sb.append('='); | |
| sb.append(value == this ? "(this Map)" : value); | |
| if (! i.hasNext()) | |
| return sb.append('}').toString(); | |
| sb.append(',').append(' '); | |
| } | |
| } | |
| /** | |
| * Returns a shallow copy of this {@code AbstractMap} instance: the keys | |
| * and values themselves are not cloned. | |
| * | |
| * @return a shallow copy of this map | |
| */ | |
| protected Object clone() throws CloneNotSupportedException { | |
| AbstractMap<?,?> result = (AbstractMap<?,?>)super.clone(); | |
| result.keySet = null; | |
| result.values = null; | |
| return result; | |
| } | |
| /** | |
| * Utility method for SimpleEntry and SimpleImmutableEntry. | |
| * Test for equality, checking for nulls. | |
| * | |
| * NB: Do not replace with Object.equals until JDK-8015417 is resolved. | |
| */ | |
| private static boolean eq(Object o1, Object o2) { | |
| return o1 == null ? o2 == null : o1.equals(o2); | |
| } | |
| // Implementation Note: SimpleEntry and SimpleImmutableEntry | |
| // are distinct unrelated classes, even though they share | |
| // some code. Since you can't add or subtract final-ness | |
| // of a field in a subclass, they can't share representations, | |
| // and the amount of duplicated code is too small to warrant | |
| // exposing a common abstract class. | |
| /** | |
| * An Entry maintaining a key and a value. The value may be | |
| * changed using the {@code setValue} method. Instances of | |
| * this class are not associated with any map nor with any | |
| * map's entry-set view. | |
| * | |
| * @apiNote | |
| * This class facilitates the process of building custom map | |
| * implementations. For example, it may be convenient to return | |
| * arrays of {@code SimpleEntry} instances in method | |
| * {@code Map.entrySet().toArray}. | |
| * | |
| * @param <K> the type of key | |
| * @param <V> the type of the value | |
| * | |
| * @since 1.6 | |
| */ | |
| public static class SimpleEntry<K,V> | |
| implements Entry<K,V>, java.io.Serializable | |
| { | |
| @java.io.Serial | |
| private static final long serialVersionUID = -8499721149061103585L; | |
| /** @serial */ | |
| @SuppressWarnings("serial") // Conditionally serializable | |
| private final K key; | |
| /** @serial */ | |
| @SuppressWarnings("serial") // Conditionally serializable | |
| private V value; | |
| /** | |
| * Creates an entry representing a mapping from the specified | |
| * key to the specified value. | |
| * | |
| * @param key the key represented by this entry | |
| * @param value the value represented by this entry | |
| */ | |
| public SimpleEntry(K key, V value) { | |
| this.key = key; | |
| this.value = value; | |
| } | |
| /** | |
| * Creates an entry representing the same mapping as the | |
| * specified entry. | |
| * | |
| * @param entry the entry to copy | |
| */ | |
| public SimpleEntry(Entry<? extends K, ? extends V> entry) { | |
| this.key = entry.getKey(); | |
| this.value = entry.getValue(); | |
| } | |
| /** | |
| * Returns the key corresponding to this entry. | |
| * | |
| * @return the key corresponding to this entry | |
| */ | |
| public K getKey() { | |
| return key; | |
| } | |
| /** | |
| * Returns the value corresponding to this entry. | |
| * | |
| * @return the value corresponding to this entry | |
| */ | |
| public V getValue() { | |
| return value; | |
| } | |
| /** | |
| * Replaces the value corresponding to this entry with the specified | |
| * value. | |
| * | |
| * @param value new value to be stored in this entry | |
| * @return the old value corresponding to the entry | |
| */ | |
| public V setValue(V value) { | |
| V oldValue = this.value; | |
| this.value = value; | |
| return oldValue; | |
| } | |
| /** | |
| * Compares the specified object with this entry for equality. | |
| * Returns {@code true} if the given object is also a map entry and | |
| * the two entries represent the same mapping. More formally, two | |
| * entries {@code e1} and {@code e2} represent the same mapping | |
| * if<pre> | |
| * (e1.getKey()==null ? | |
| * e2.getKey()==null : | |
| * e1.getKey().equals(e2.getKey())) | |
| * && | |
| * (e1.getValue()==null ? | |
| * e2.getValue()==null : | |
| * e1.getValue().equals(e2.getValue()))</pre> | |
| * This ensures that the {@code equals} method works properly across | |
| * different implementations of the {@code Map.Entry} interface. | |
| * | |
| * @param o object to be compared for equality with this map entry | |
| * @return {@code true} if the specified object is equal to this map | |
| * entry | |
| * @see #hashCode | |
| */ | |
| public boolean equals(Object o) { | |
| return o instanceof Map.Entry<?, ?> e | |
| && eq(key, e.getKey()) | |
| && eq(value, e.getValue()); | |
| } | |
| /** | |
| * Returns the hash code value for this map entry. The hash code | |
| * of a map entry {@code e} is defined to be: <pre> | |
| * (e.getKey()==null ? 0 : e.getKey().hashCode()) ^ | |
| * (e.getValue()==null ? 0 : e.getValue().hashCode())</pre> | |
| * This ensures that {@code e1.equals(e2)} implies that | |
| * {@code e1.hashCode()==e2.hashCode()} for any two Entries | |
| * {@code e1} and {@code e2}, as required by the general | |
| * contract of {@link Object#hashCode}. | |
| * | |
| * @return the hash code value for this map entry | |
| * @see #equals | |
| */ | |
| public int hashCode() { | |
| return (key == null ? 0 : key.hashCode()) ^ | |
| (value == null ? 0 : value.hashCode()); | |
| } | |
| /** | |
| * Returns a String representation of this map entry. This | |
| * implementation returns the string representation of this | |
| * entry's key followed by the equals character ("{@code =}") | |
| * followed by the string representation of this entry's value. | |
| * | |
| * @return a String representation of this map entry | |
| */ | |
| public String toString() { | |
| return key + "=" + value; | |
| } | |
| } | |
| /** | |
| * An unmodifiable Entry maintaining a key and a value. This class | |
| * does not support the {@code setValue} method. Instances of | |
| * this class are not associated with any map nor with any map's | |
| * entry-set view. | |
| * | |
| * @apiNote | |
| * Instances of this class are not necessarily immutable, as the key | |
| * and value may be mutable. An instance of <i>this specific class</i> | |
| * is unmodifiable, because the key and value references cannot be | |
| * changed. A reference of this <i>type</i> may not be unmodifiable, | |
| * as a subclass may be modifiable or may provide the appearance of modifiability. | |
| * <p> | |
| * This class may be convenient in methods that return thread-safe snapshots of | |
| * key-value mappings. For alternatives, see the | |
| * {@link Map#entry Map::entry} and {@link Map.Entry#copyOf Map.Entry::copyOf} | |
| * methods. | |
| * | |
| * @param <K> the type of the keys | |
| * @param <V> the type of the value | |
| * @since 1.6 | |
| */ | |
| public static class SimpleImmutableEntry<K,V> | |
| implements Entry<K,V>, java.io.Serializable | |
| { | |
| @java.io.Serial | |
| private static final long serialVersionUID = 7138329143949025153L; | |
| /** @serial */ | |
| @SuppressWarnings("serial") // Not statically typed as Serializable | |
| private final K key; | |
| /** @serial */ | |
| @SuppressWarnings("serial") // Not statically typed as Serializable | |
| private final V value; | |
| /** | |
| * Creates an entry representing a mapping from the specified | |
| * key to the specified value. | |
| * | |
| * @param key the key represented by this entry | |
| * @param value the value represented by this entry | |
| */ | |
| public SimpleImmutableEntry(K key, V value) { | |
| this.key = key; | |
| this.value = value; | |
| } | |
| /** | |
| * Creates an entry representing the same mapping as the | |
| * specified entry. | |
| * | |
| * @param entry the entry to copy | |
| */ | |
| public SimpleImmutableEntry(Entry<? extends K, ? extends V> entry) { | |
| this.key = entry.getKey(); | |
| this.value = entry.getValue(); | |
| } | |
| /** | |
| * Returns the key corresponding to this entry. | |
| * | |
| * @return the key corresponding to this entry | |
| */ | |
| public K getKey() { | |
| return key; | |
| } | |
| /** | |
| * Returns the value corresponding to this entry. | |
| * | |
| * @return the value corresponding to this entry | |
| */ | |
| public V getValue() { | |
| return value; | |
| } | |
| /** | |
| * Replaces the value corresponding to this entry with the specified | |
| * value (optional operation). This implementation simply throws | |
| * {@code UnsupportedOperationException}, as this class implements | |
| * an unmodifiable map entry. | |
| * | |
| * @implSpec | |
| * The implementation in this class always throws {@code UnsupportedOperationException}. | |
| * | |
| * @param value new value to be stored in this entry | |
| * @return (Does not return) | |
| * @throws UnsupportedOperationException always | |
| */ | |
| public V setValue(V value) { | |
| throw new UnsupportedOperationException(); | |
| } | |
| /** | |
| * Compares the specified object with this entry for equality. | |
| * Returns {@code true} if the given object is also a map entry and | |
| * the two entries represent the same mapping. More formally, two | |
| * entries {@code e1} and {@code e2} represent the same mapping | |
| * if<pre> | |
| * (e1.getKey()==null ? | |
| * e2.getKey()==null : | |
| * e1.getKey().equals(e2.getKey())) | |
| * && | |
| * (e1.getValue()==null ? | |
| * e2.getValue()==null : | |
| * e1.getValue().equals(e2.getValue()))</pre> | |
| * This ensures that the {@code equals} method works properly across | |
| * different implementations of the {@code Map.Entry} interface. | |
| * | |
| * @param o object to be compared for equality with this map entry | |
| * @return {@code true} if the specified object is equal to this map | |
| * entry | |
| * @see #hashCode | |
| */ | |
| public boolean equals(Object o) { | |
| return o instanceof Map.Entry<?, ?> e | |
| && eq(key, e.getKey()) | |
| && eq(value, e.getValue()); | |
| } | |
| /** | |
| * Returns the hash code value for this map entry. The hash code | |
| * of a map entry {@code e} is defined to be: <pre> | |
| * (e.getKey()==null ? 0 : e.getKey().hashCode()) ^ | |
| * (e.getValue()==null ? 0 : e.getValue().hashCode())</pre> | |
| * This ensures that {@code e1.equals(e2)} implies that | |
| * {@code e1.hashCode()==e2.hashCode()} for any two Entries | |
| * {@code e1} and {@code e2}, as required by the general | |
| * contract of {@link Object#hashCode}. | |
| * | |
| * @return the hash code value for this map entry | |
| * @see #equals | |
| */ | |
| public int hashCode() { | |
| return (key == null ? 0 : key.hashCode()) ^ | |
| (value == null ? 0 : value.hashCode()); | |
| } | |
| /** | |
| * Returns a String representation of this map entry. This | |
| * implementation returns the string representation of this | |
| * entry's key followed by the equals character ("{@code =}") | |
| * followed by the string representation of this entry's value. | |
| * | |
| * @return a String representation of this map entry | |
| */ | |
| public String toString() { | |
| return key + "=" + value; | |
| } | |
| } | |
| /** | |
| * Delegates all Collection methods to the provided non-sequenced map view, | |
| * except add() and addAll(), which throw UOE. This provides the common | |
| * implementation of each of the sequenced views of the SequencedMap. | |
| * Each view implementation is a subclass that provides an instance of the | |
| * non-sequenced view as a delegate and an implementation of reversed(). | |
| * Each view also inherits the default implementations for the sequenced | |
| * methods from SequencedCollection or SequencedSet. | |
| * <p> | |
| * Ideally this would be a private class within SequencedMap, but private | |
| * classes aren't permitted within interfaces. | |
| * <p> | |
| * The non-sequenced map view is obtained by calling the abstract view() | |
| * method for each operation. | |
| * | |
| * @param <E> the view's element type | |
| */ | |
| /* non-public */ abstract static class ViewCollection<E> implements Collection<E> { | |
| UnsupportedOperationException uoe() { return new UnsupportedOperationException(); } | |
| // convert null entry return values into NSEE | |
| static <T extends Map.Entry<?,?>> T nsee(T entry) { | |
| if (entry == null) { | |
| throw new NoSuchElementException(); | |
| } else { | |
| return entry; | |
| } | |
| } | |
| abstract Collection<E> view(); | |
| public boolean add(E t) { throw uoe(); } | |
| public boolean addAll(Collection<? extends E> c) { throw uoe(); } | |
| public void clear() { view().clear(); } | |
| public boolean contains(Object o) { return view().contains(o); } | |
| public boolean containsAll(Collection<?> c) { return view().containsAll(c); } | |
| public void forEach(Consumer<? super E> c) { view().forEach(c); } | |
| public boolean isEmpty() { return view().isEmpty(); } | |
| public Iterator<E> iterator() { return view().iterator(); } | |
| public Stream<E> parallelStream() { return view().parallelStream(); } | |
| public boolean remove(Object o) { return view().remove(o); } | |
| public boolean removeAll(Collection<?> c) { return view().removeAll(c); } | |
| public boolean removeIf(Predicate<? super E> filter) { return view().removeIf(filter); } | |
| public boolean retainAll(Collection<?> c) { return view().retainAll(c); } | |
| public int size() { return view().size(); } | |
| public Spliterator<E> spliterator() { return view().spliterator(); } | |
| public Stream<E> stream() { return view().stream(); } | |
| public Object[] toArray() { return view().toArray(); } | |
| public <T> T[] toArray(IntFunction<T[]> generator) { return view().toArray(generator); } | |
| public <T> T[] toArray(T[] a) { return view().toArray(a); } | |
| public String toString() { return view().toString(); } | |
| } | |
| // Iterator implementations. | |
| final class KeyIterator implements Iterator<K> { | |
| private final Iterator<Entry<K,V>> i = entrySet().iterator(); | |
| public boolean hasNext() { return i.hasNext(); } | |
| public void remove() { i.remove(); } | |
| public K next() { return i.next().getKey(); } | |
| } | |
| final class ValueIterator implements Iterator<V> { | |
| private final Iterator<Entry<K,V>> i = entrySet().iterator(); | |
| public boolean hasNext() { return i.hasNext(); } | |
| public void remove() { i.remove(); } | |
| public V next() { return i.next().getValue(); } | |
| } | |
| } |