| /* | |
| * Copyright (c) 1997, 2024, 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.function.Consumer; | |
| import java.util.function.BiConsumer; | |
| import java.util.function.BiFunction; | |
| import java.io.IOException; | |
| import java.util.function.Function; | |
| /** | |
| * <p>Hash table and linked list implementation of the {@code Map} interface, | |
| * with well-defined encounter order. This implementation differs from | |
| * {@code HashMap} in that it maintains a doubly-linked list running through all of | |
| * its entries. This linked list defines the encounter order (the order of iteration), | |
| * which is normally the order in which keys were inserted into the map | |
| * (<i>insertion-order</i>). The least recently inserted entry (the eldest) is | |
| * first, and the youngest entry is last. Note that encounter order is not affected | |
| * if a key is <i>re-inserted</i> into the map with the {@code put} method. (A key | |
| * {@code k} is reinserted into a map {@code m} if {@code m.put(k, v)} is invoked when | |
| * {@code m.containsKey(k)} would return {@code true} immediately prior to | |
| * the invocation.) The reverse-ordered view of this map is in the opposite order, with | |
| * the youngest entry appearing first and the eldest entry appearing last. | |
| * The encounter order of entries already in the map can be changed by using | |
| * the {@link #putFirst putFirst} and {@link #putLast putLast} methods. | |
| * | |
| * <p>This implementation spares its clients from the unspecified, generally | |
| * chaotic ordering provided by {@link HashMap} (and {@link Hashtable}), | |
| * without incurring the increased cost associated with {@link TreeMap}. It | |
| * can be used to produce a copy of a map that has the same order as the | |
| * original, regardless of the original map's implementation: | |
| * <pre>{@code | |
| * void foo(Map<String, Integer> m) { | |
| * Map<String, Integer> copy = new LinkedHashMap<>(m); | |
| * ... | |
| * } | |
| * }</pre> | |
| * This technique is particularly useful if a module takes a map on input, | |
| * copies it, and later returns results whose order is determined by that of | |
| * the copy. (Clients generally appreciate having things returned in the same | |
| * order they were presented.) | |
| * | |
| * <p>A special {@link #LinkedHashMap(int,float,boolean) constructor} is | |
| * provided to create a linked hash map whose encounter order is the order | |
| * in which its entries were last accessed, from least-recently accessed to | |
| * most-recently (<i>access-order</i>). This kind of map is well-suited to | |
| * building LRU caches. Invoking the {@code put}, {@code putIfAbsent}, | |
| * {@code get}, {@code getOrDefault}, {@code compute}, {@code computeIfAbsent}, | |
| * {@code computeIfPresent}, or {@code merge} methods results | |
| * in an access to the corresponding entry (assuming it exists after the | |
| * invocation completes). The {@code replace} methods only result in an access | |
| * of the entry if the value is replaced. The {@code putAll} method generates one | |
| * entry access for each mapping in the specified map, in the order that | |
| * key-value mappings are provided by the specified map's entry set iterator. | |
| * <i>No other methods generate entry accesses.</i> Invoking these methods on the | |
| * reversed view generates accesses to entries on the backing map. Note that in the | |
| * reversed view, an access to an entry moves it first in encounter order. | |
| * Explicit-positioning methods such as {@code putFirst} or {@code lastEntry}, whether on | |
| * the map or on its reverse-ordered view, perform the positioning operation and | |
| * do not generate entry accesses. Operations on the {@code keySet}, {@code values}, | |
| * and {@code entrySet} views or on their sequenced counterparts do <i>not</i> affect | |
| * the encounter order of the backing map. | |
| * | |
| * <p>The {@link #removeEldestEntry(Map.Entry)} method may be overridden to | |
| * impose a policy for removing stale mappings automatically when new mappings | |
| * are added to the map. Alternatively, since the "eldest" entry is the first | |
| * entry in encounter order, programs can inspect and remove stale mappings through | |
| * use of the {@link #firstEntry firstEntry} and {@link #pollFirstEntry pollFirstEntry} | |
| * methods. | |
| * | |
| * <p>This class provides all of the optional {@code Map} and {@code SequencedMap} operations, | |
| * and it permits null elements. Like {@code HashMap}, it provides constant-time | |
| * performance for the basic operations ({@code add}, {@code contains} and | |
| * {@code remove}), assuming the hash function disperses elements | |
| * properly among the buckets. Performance is likely to be just slightly | |
| * below that of {@code HashMap}, due to the added expense of maintaining the | |
| * linked list, with one exception: Iteration over the collection-views | |
| * of a {@code LinkedHashMap} requires time proportional to the <i>size</i> | |
| * of the map, regardless of its capacity. Iteration over a {@code HashMap} | |
| * is likely to be more expensive, requiring time proportional to its | |
| * <i>capacity</i>. | |
| * | |
| * <p>A linked hash map has two parameters that affect its performance: | |
| * <i>initial capacity</i> and <i>load factor</i>. They are defined precisely | |
| * as for {@code HashMap}. Note, however, that the penalty for choosing an | |
| * excessively high value for initial capacity is less severe for this class | |
| * than for {@code HashMap}, as iteration times for this class are unaffected | |
| * by capacity. | |
| * | |
| * <p><strong>Note that this implementation is not synchronized.</strong> | |
| * If multiple threads access a linked hash map concurrently, and at least | |
| * one of the threads modifies the map structurally, it <em>must</em> be | |
| * synchronized externally. This is typically accomplished by | |
| * synchronizing on some object that naturally encapsulates the map. | |
| * | |
| * If no such object exists, the map should be "wrapped" using the | |
| * {@link Collections#synchronizedMap Collections.synchronizedMap} | |
| * method. This is best done at creation time, to prevent accidental | |
| * unsynchronized access to the map:<pre> | |
| * Map m = Collections.synchronizedMap(new LinkedHashMap(...));</pre> | |
| * | |
| * A structural modification is any operation that adds or deletes one or more | |
| * mappings or, in the case of access-ordered linked hash maps, affects | |
| * iteration order. In insertion-ordered linked hash maps, merely changing | |
| * the value associated with a key that is already contained in the map is not | |
| * a structural modification. <strong>In access-ordered linked hash maps, | |
| * merely querying the map with {@code get} is a structural modification. | |
| * </strong>) | |
| * | |
| * <p>The iterators returned by the {@code iterator} method of the collections | |
| * returned by all of this class's collection view methods are | |
| * <em>fail-fast</em>: if the map is structurally modified at any time after | |
| * the iterator is created, in any way except through the iterator's own | |
| * {@code remove} method, the iterator will throw a {@link | |
| * ConcurrentModificationException}. Thus, in the face of concurrent | |
| * modification, the iterator fails quickly and cleanly, rather than risking | |
| * arbitrary, non-deterministic behavior at an undetermined time in the future. | |
| * | |
| * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed | |
| * as it is, generally speaking, impossible to make any hard guarantees in the | |
| * presence of unsynchronized concurrent modification. Fail-fast iterators | |
| * throw {@code ConcurrentModificationException} on a best-effort basis. | |
| * Therefore, it would be wrong to write a program that depended on this | |
| * exception for its correctness: <i>the fail-fast behavior of iterators | |
| * should be used only to detect bugs.</i> | |
| * | |
| * <p>The spliterators returned by the spliterator method of the collections | |
| * returned by all of this class's collection view methods are | |
| * <em><a href="Spliterator.html#binding">late-binding</a></em>, | |
| * <em>fail-fast</em>, and additionally report {@link Spliterator#ORDERED}. | |
| * | |
| * <p>This class is a member of the | |
| * <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework"> | |
| * Java Collections Framework</a>. | |
| * | |
| * @implNote | |
| * The spliterators returned by the spliterator method of the collections | |
| * returned by all of this class's collection view methods are created from | |
| * the iterators of the corresponding collections. | |
| * | |
| * @param <K> the type of keys maintained by this map | |
| * @param <V> the type of mapped values | |
| * | |
| * @author Josh Bloch | |
| * @see Object#hashCode() | |
| * @see Collection | |
| * @see Map | |
| * @see HashMap | |
| * @see TreeMap | |
| * @see Hashtable | |
| * @since 1.4 | |
| */ | |
| public class LinkedHashMap<K,V> | |
| extends HashMap<K,V> | |
| implements SequencedMap<K,V> | |
| { | |
| /* | |
| * Implementation note. A previous version of this class was | |
| * internally structured a little differently. Because superclass | |
| * HashMap now uses trees for some of its nodes, class | |
| * LinkedHashMap.Entry is now treated as intermediary node class | |
| * that can also be converted to tree form. The name of this | |
| * class, LinkedHashMap.Entry, is confusing in several ways in its | |
| * current context, but cannot be changed. Otherwise, even though | |
| * it is not exported outside this package, some existing source | |
| * code is known to have relied on a symbol resolution corner case | |
| * rule in calls to removeEldestEntry that suppressed compilation | |
| * errors due to ambiguous usages. So, we keep the name to | |
| * preserve unmodified compilability. | |
| * | |
| * The changes in node classes also require using two fields | |
| * (head, tail) rather than a pointer to a header node to maintain | |
| * the doubly-linked before/after list. This class also | |
| * previously used a different style of callback methods upon | |
| * access, insertion, and removal. | |
| */ | |
| /** | |
| * HashMap.Node subclass for normal LinkedHashMap entries. | |
| */ | |
| static class Entry<K,V> extends HashMap.Node<K,V> { | |
| Entry<K,V> before, after; | |
| Entry(int hash, K key, V value, Node<K,V> next) { | |
| super(hash, key, value, next); | |
| } | |
| } | |
| @java.io.Serial | |
| private static final long serialVersionUID = 3801124242820219131L; | |
| /** | |
| * The head (eldest) of the doubly linked list. | |
| */ | |
| transient LinkedHashMap.Entry<K,V> head; | |
| /** | |
| * The tail (youngest) of the doubly linked list. | |
| */ | |
| transient LinkedHashMap.Entry<K,V> tail; | |
| /** | |
| * The iteration ordering method for this linked hash map: {@code true} | |
| * for access-order, {@code false} for insertion-order. | |
| * | |
| * @serial | |
| */ | |
| final boolean accessOrder; | |
| // internal utilities | |
| // link at the end of list | |
| private void linkNodeAtEnd(LinkedHashMap.Entry<K,V> p) { | |
| if (putMode == PUT_FIRST) { | |
| LinkedHashMap.Entry<K,V> first = head; | |
| head = p; | |
| if (first == null) | |
| tail = p; | |
| else { | |
| p.after = first; | |
| first.before = p; | |
| } | |
| } else { | |
| LinkedHashMap.Entry<K,V> last = tail; | |
| tail = p; | |
| if (last == null) | |
| head = p; | |
| else { | |
| p.before = last; | |
| last.after = p; | |
| } | |
| } | |
| } | |
| // apply src's links to dst | |
| private void transferLinks(LinkedHashMap.Entry<K,V> src, | |
| LinkedHashMap.Entry<K,V> dst) { | |
| LinkedHashMap.Entry<K,V> b = dst.before = src.before; | |
| LinkedHashMap.Entry<K,V> a = dst.after = src.after; | |
| if (b == null) | |
| head = dst; | |
| else | |
| b.after = dst; | |
| if (a == null) | |
| tail = dst; | |
| else | |
| a.before = dst; | |
| } | |
| // overrides of HashMap hook methods | |
| void reinitialize() { | |
| super.reinitialize(); | |
| head = tail = null; | |
| } | |
| Node<K,V> newNode(int hash, K key, V value, Node<K,V> e) { | |
| LinkedHashMap.Entry<K,V> p = | |
| new LinkedHashMap.Entry<>(hash, key, value, e); | |
| linkNodeAtEnd(p); | |
| return p; | |
| } | |
| Node<K,V> replacementNode(Node<K,V> p, Node<K,V> next) { | |
| LinkedHashMap.Entry<K,V> q = (LinkedHashMap.Entry<K,V>)p; | |
| LinkedHashMap.Entry<K,V> t = | |
| new LinkedHashMap.Entry<>(q.hash, q.key, q.value, next); | |
| transferLinks(q, t); | |
| return t; | |
| } | |
| TreeNode<K,V> newTreeNode(int hash, K key, V value, Node<K,V> next) { | |
| TreeNode<K,V> p = new TreeNode<>(hash, key, value, next); | |
| linkNodeAtEnd(p); | |
| return p; | |
| } | |
| TreeNode<K,V> replacementTreeNode(Node<K,V> p, Node<K,V> next) { | |
| LinkedHashMap.Entry<K,V> q = (LinkedHashMap.Entry<K,V>)p; | |
| TreeNode<K,V> t = new TreeNode<>(q.hash, q.key, q.value, next); | |
| transferLinks(q, t); | |
| return t; | |
| } | |
| void afterNodeRemoval(Node<K,V> e) { // unlink | |
| LinkedHashMap.Entry<K,V> p = | |
| (LinkedHashMap.Entry<K,V>)e, b = p.before, a = p.after; | |
| p.before = p.after = null; | |
| if (b == null) | |
| head = a; | |
| else | |
| b.after = a; | |
| if (a == null) | |
| tail = b; | |
| else | |
| a.before = b; | |
| } | |
| void afterNodeInsertion(boolean evict) { // possibly remove eldest | |
| LinkedHashMap.Entry<K,V> first; | |
| if (evict && (first = head) != null && removeEldestEntry(first)) { | |
| K key = first.key; | |
| removeNode(hash(key), key, null, false, true); | |
| } | |
| } | |
| static final int PUT_NORM = 0; | |
| static final int PUT_FIRST = 1; | |
| static final int PUT_LAST = 2; | |
| transient int putMode = PUT_NORM; | |
| // Called after update, but not after insertion | |
| void afterNodeAccess(Node<K,V> e) { | |
| LinkedHashMap.Entry<K,V> last; | |
| LinkedHashMap.Entry<K,V> first; | |
| if ((putMode == PUT_LAST || (putMode == PUT_NORM && accessOrder)) && (last = tail) != e) { | |
| // move node to last | |
| LinkedHashMap.Entry<K,V> p = | |
| (LinkedHashMap.Entry<K,V>)e, b = p.before, a = p.after; | |
| p.after = null; | |
| if (b == null) | |
| head = a; | |
| else | |
| b.after = a; | |
| if (a != null) | |
| a.before = b; | |
| else | |
| last = b; | |
| if (last == null) | |
| head = p; | |
| else { | |
| p.before = last; | |
| last.after = p; | |
| } | |
| tail = p; | |
| ++modCount; | |
| } else if (putMode == PUT_FIRST && (first = head) != e) { | |
| // move node to first | |
| LinkedHashMap.Entry<K,V> p = | |
| (LinkedHashMap.Entry<K,V>)e, b = p.before, a = p.after; | |
| p.before = null; | |
| if (a == null) | |
| tail = b; | |
| else | |
| a.before = b; | |
| if (b != null) | |
| b.after = a; | |
| else | |
| first = a; | |
| if (first == null) | |
| tail = p; | |
| else { | |
| p.after = first; | |
| first.before = p; | |
| } | |
| head = p; | |
| ++modCount; | |
| } | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * <p> | |
| * If this map already contains a mapping for this key, the mapping is relocated if necessary | |
| * so that it is first in encounter order. | |
| * | |
| * @since 21 | |
| */ | |
| public V putFirst(K k, V v) { | |
| try { | |
| putMode = PUT_FIRST; | |
| return this.put(k, v); | |
| } finally { | |
| putMode = PUT_NORM; | |
| } | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * <p> | |
| * If this map already contains a mapping for this key, the mapping is relocated if necessary | |
| * so that it is last in encounter order. | |
| * | |
| * @since 21 | |
| */ | |
| public V putLast(K k, V v) { | |
| try { | |
| putMode = PUT_LAST; | |
| return this.put(k, v); | |
| } finally { | |
| putMode = PUT_NORM; | |
| } | |
| } | |
| void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException { | |
| for (LinkedHashMap.Entry<K,V> e = head; e != null; e = e.after) { | |
| s.writeObject(e.key); | |
| s.writeObject(e.value); | |
| } | |
| } | |
| /** | |
| * Constructs an empty insertion-ordered {@code LinkedHashMap} instance | |
| * with the specified initial capacity and load factor. | |
| * | |
| * @apiNote | |
| * To create a {@code LinkedHashMap} with an initial capacity that accommodates | |
| * an expected number of mappings, use {@link #newLinkedHashMap(int) newLinkedHashMap}. | |
| * | |
| * @param initialCapacity the initial capacity | |
| * @param loadFactor the load factor | |
| * @throws IllegalArgumentException if the initial capacity is negative | |
| * or the load factor is nonpositive | |
| */ | |
| public LinkedHashMap(int initialCapacity, float loadFactor) { | |
| super(initialCapacity, loadFactor); | |
| accessOrder = false; | |
| } | |
| /** | |
| * Constructs an empty insertion-ordered {@code LinkedHashMap} instance | |
| * with the specified initial capacity and a default load factor (0.75). | |
| * | |
| * @apiNote | |
| * To create a {@code LinkedHashMap} with an initial capacity that accommodates | |
| * an expected number of mappings, use {@link #newLinkedHashMap(int) newLinkedHashMap}. | |
| * | |
| * @param initialCapacity the initial capacity | |
| * @throws IllegalArgumentException if the initial capacity is negative | |
| */ | |
| public LinkedHashMap(int initialCapacity) { | |
| super(initialCapacity); | |
| accessOrder = false; | |
| } | |
| /** | |
| * Constructs an empty insertion-ordered {@code LinkedHashMap} instance | |
| * with the default initial capacity (16) and load factor (0.75). | |
| */ | |
| public LinkedHashMap() { | |
| super(); | |
| accessOrder = false; | |
| } | |
| /** | |
| * Constructs an insertion-ordered {@code LinkedHashMap} instance with | |
| * the same mappings as the specified map. The {@code LinkedHashMap} | |
| * instance is created with a default load factor (0.75) and an initial | |
| * capacity sufficient to hold the mappings in the specified map. | |
| * | |
| * @param m the map whose mappings are to be placed in this map | |
| * @throws NullPointerException if the specified map is null | |
| */ | |
| @SuppressWarnings("this-escape") | |
| public LinkedHashMap(Map<? extends K, ? extends V> m) { | |
| super(); | |
| accessOrder = false; | |
| putMapEntries(m, false); | |
| } | |
| /** | |
| * Constructs an empty {@code LinkedHashMap} instance with the | |
| * specified initial capacity, load factor and ordering mode. | |
| * | |
| * @param initialCapacity the initial capacity | |
| * @param loadFactor the load factor | |
| * @param accessOrder the ordering mode - {@code true} for | |
| * access-order, {@code false} for insertion-order | |
| * @throws IllegalArgumentException if the initial capacity is negative | |
| * or the load factor is nonpositive | |
| */ | |
| public LinkedHashMap(int initialCapacity, | |
| float loadFactor, | |
| boolean accessOrder) { | |
| super(initialCapacity, loadFactor); | |
| this.accessOrder = accessOrder; | |
| } | |
| /** | |
| * Returns {@code true} if this map maps one or more keys to the | |
| * specified value. | |
| * | |
| * @param value value whose presence in this map is to be tested | |
| * @return {@code true} if this map maps one or more keys to the | |
| * specified value | |
| */ | |
| public boolean containsValue(Object value) { | |
| for (LinkedHashMap.Entry<K,V> e = head; e != null; e = e.after) { | |
| V v = e.value; | |
| if (v == value || (value != null && value.equals(v))) | |
| return true; | |
| } | |
| return false; | |
| } | |
| /** | |
| * Returns the value to which the specified key is mapped, | |
| * or {@code null} if this map contains no mapping for the key. | |
| * | |
| * <p>More formally, if this map contains a mapping from a key | |
| * {@code k} to a value {@code v} such that {@code (key==null ? k==null : | |
| * key.equals(k))}, then this method returns {@code v}; otherwise | |
| * it returns {@code null}. (There can be at most one such mapping.) | |
| * | |
| * <p>A return value of {@code null} does not <i>necessarily</i> | |
| * indicate that the map contains no mapping for the key; it's also | |
| * possible that the map explicitly maps the key to {@code null}. | |
| * The {@link #containsKey containsKey} operation may be used to | |
| * distinguish these two cases. | |
| */ | |
| public V get(Object key) { | |
| Node<K,V> e; | |
| if ((e = getNode(key)) == null) | |
| return null; | |
| if (accessOrder) | |
| afterNodeAccess(e); | |
| return e.value; | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| public V getOrDefault(Object key, V defaultValue) { | |
| Node<K,V> e; | |
| if ((e = getNode(key)) == null) | |
| return defaultValue; | |
| if (accessOrder) | |
| afterNodeAccess(e); | |
| return e.value; | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| public void clear() { | |
| super.clear(); | |
| head = tail = null; | |
| } | |
| /** | |
| * Returns {@code true} if this map should remove its eldest entry. | |
| * This method is invoked by {@code put} and {@code putAll} after | |
| * inserting a new entry into the map. It provides the implementor | |
| * with the opportunity to remove the eldest entry each time a new one | |
| * is added. This is useful if the map represents a cache: it allows | |
| * the map to reduce memory consumption by deleting stale entries. | |
| * | |
| * <p>Sample use: this override will allow the map to grow up to 100 | |
| * entries and then delete the eldest entry each time a new entry is | |
| * added, maintaining a steady state of 100 entries. | |
| * <pre> | |
| * private static final int MAX_ENTRIES = 100; | |
| * | |
| * protected boolean removeEldestEntry(Map.Entry eldest) { | |
| * return size() > MAX_ENTRIES; | |
| * } | |
| * </pre> | |
| * | |
| * <p>This method typically does not modify the map in any way, | |
| * instead allowing the map to modify itself as directed by its | |
| * return value. It <i>is</i> permitted for this method to modify | |
| * the map directly, but if it does so, it <i>must</i> return | |
| * {@code false} (indicating that the map should not attempt any | |
| * further modification). The effects of returning {@code true} | |
| * after modifying the map from within this method are unspecified. | |
| * | |
| * <p>This implementation merely returns {@code false} (so that this | |
| * map acts like a normal map - the eldest element is never removed). | |
| * | |
| * @param eldest The least recently inserted entry in the map, or if | |
| * this is an access-ordered map, the least recently accessed | |
| * entry. This is the entry that will be removed if this | |
| * method returns {@code true}. If the map was empty prior | |
| * to the {@code put} or {@code putAll} invocation resulting | |
| * in this invocation, this will be the entry that was just | |
| * inserted; in other words, if the map contains a single | |
| * entry, the eldest entry is also the newest. | |
| * @return {@code true} if the eldest entry should be removed | |
| * from the map; {@code false} if it should be retained. | |
| */ | |
| protected boolean removeEldestEntry(Map.Entry<K,V> eldest) { | |
| return false; | |
| } | |
| /** | |
| * Returns a {@link Set} view of the keys contained in this map. The encounter | |
| * order of the keys in the view matches the encounter order of mappings of | |
| * this map. The set is backed by the map, so changes to the map are | |
| * reflected in the set, and vice-versa. If the map is modified | |
| * while an iteration over the set is in progress (except through | |
| * the iterator's own {@code remove} operation), the results of | |
| * the iteration are undefined. The set supports element removal, | |
| * which removes the corresponding mapping from the map, via the | |
| * {@code Iterator.remove}, {@code Set.remove}, | |
| * {@code removeAll}, {@code retainAll}, and {@code clear} | |
| * operations. It does not support the {@code add} or {@code addAll} | |
| * operations. | |
| * Its {@link Spliterator} typically provides faster sequential | |
| * performance but much poorer parallel performance than that of | |
| * {@code HashMap}. | |
| * | |
| * @return a set view of the keys contained in this map | |
| */ | |
| public Set<K> keySet() { | |
| return sequencedKeySet(); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * <p> | |
| * The returned view has the same characteristics as specified for the view | |
| * returned by the {@link #keySet keySet} method. | |
| * | |
| * @return {@inheritDoc} | |
| * @since 21 | |
| */ | |
| public SequencedSet<K> sequencedKeySet() { | |
| Set<K> ks = keySet; | |
| if (ks == null) { | |
| SequencedSet<K> sks = new LinkedKeySet(false); | |
| keySet = sks; | |
| return sks; | |
| } else { | |
| // The cast should never fail, since the only assignment of non-null to keySet is | |
| // above, and assignments in AbstractMap and HashMap are in overridden methods. | |
| return (SequencedSet<K>) ks; | |
| } | |
| } | |
| static <K1,V1> Node<K1,V1> nsee(Node<K1,V1> node) { | |
| if (node == null) | |
| throw new NoSuchElementException(); | |
| else | |
| return node; | |
| } | |
| final <T> T[] keysToArray(T[] a) { | |
| return keysToArray(a, false); | |
| } | |
| final <T> T[] keysToArray(T[] a, boolean reversed) { | |
| Object[] r = a; | |
| int idx = 0; | |
| if (reversed) { | |
| for (LinkedHashMap.Entry<K,V> e = tail; e != null; e = e.before) { | |
| r[idx++] = e.key; | |
| } | |
| } else { | |
| for (LinkedHashMap.Entry<K,V> e = head; e != null; e = e.after) { | |
| r[idx++] = e.key; | |
| } | |
| } | |
| return a; | |
| } | |
| final <T> T[] valuesToArray(T[] a, boolean reversed) { | |
| Object[] r = a; | |
| int idx = 0; | |
| if (reversed) { | |
| for (LinkedHashMap.Entry<K,V> e = tail; e != null; e = e.before) { | |
| r[idx++] = e.value; | |
| } | |
| } else { | |
| for (LinkedHashMap.Entry<K,V> e = head; e != null; e = e.after) { | |
| r[idx++] = e.value; | |
| } | |
| } | |
| return a; | |
| } | |
| final class LinkedKeySet extends AbstractSet<K> implements SequencedSet<K> { | |
| final boolean reversed; | |
| LinkedKeySet(boolean reversed) { this.reversed = reversed; } | |
| public final int size() { return size; } | |
| public final void clear() { LinkedHashMap.this.clear(); } | |
| public final Iterator<K> iterator() { | |
| return new LinkedKeyIterator(reversed); | |
| } | |
| public final boolean contains(Object o) { return containsKey(o); } | |
| public final boolean remove(Object key) { | |
| return removeNode(hash(key), key, null, false, true) != null; | |
| } | |
| public final Spliterator<K> spliterator() { | |
| return Spliterators.spliterator(this, Spliterator.SIZED | | |
| Spliterator.ORDERED | | |
| Spliterator.DISTINCT); | |
| } | |
| public Object[] toArray() { | |
| return keysToArray(new Object[size], reversed); | |
| } | |
| public <T> T[] toArray(T[] a) { | |
| return keysToArray(prepareArray(a), reversed); | |
| } | |
| public final void forEach(Consumer<? super K> action) { | |
| if (action == null) | |
| throw new NullPointerException(); | |
| int mc = modCount; | |
| if (reversed) { | |
| for (LinkedHashMap.Entry<K,V> e = tail; e != null; e = e.before) | |
| action.accept(e.key); | |
| } else { | |
| for (LinkedHashMap.Entry<K,V> e = head; e != null; e = e.after) | |
| action.accept(e.key); | |
| } | |
| if (modCount != mc) | |
| throw new ConcurrentModificationException(); | |
| } | |
| public final void addFirst(K k) { throw new UnsupportedOperationException(); } | |
| public final void addLast(K k) { throw new UnsupportedOperationException(); } | |
| public final K getFirst() { return nsee(reversed ? tail : head).key; } | |
| public final K getLast() { return nsee(reversed ? head : tail).key; } | |
| public final K removeFirst() { | |
| var node = nsee(reversed ? tail : head); | |
| removeNode(node.hash, node.key, null, false, false); | |
| return node.key; | |
| } | |
| public final K removeLast() { | |
| var node = nsee(reversed ? head : tail); | |
| removeNode(node.hash, node.key, null, false, false); | |
| return node.key; | |
| } | |
| public SequencedSet<K> reversed() { | |
| if (reversed) { | |
| return LinkedHashMap.this.sequencedKeySet(); | |
| } else { | |
| return new LinkedKeySet(true); | |
| } | |
| } | |
| } | |
| /** | |
| * Returns a {@link Collection} view of the values contained in this map. The | |
| * encounter order of values in the view matches the encounter order of entries in | |
| * this map. The collection is backed by the map, so changes to the map are | |
| * reflected in the collection, and vice-versa. If the map is | |
| * modified while an iteration over the collection is in progress | |
| * (except through the iterator's own {@code remove} operation), | |
| * the results of the iteration are undefined. The collection | |
| * supports element removal, which removes the corresponding | |
| * mapping from the map, via the {@code Iterator.remove}, | |
| * {@code Collection.remove}, {@code removeAll}, | |
| * {@code retainAll} and {@code clear} operations. It does not | |
| * support the {@code add} or {@code addAll} operations. | |
| * Its {@link Spliterator} typically provides faster sequential | |
| * performance but much poorer parallel performance than that of | |
| * {@code HashMap}. | |
| * | |
| * @return a view of the values contained in this map | |
| */ | |
| public Collection<V> values() { | |
| return sequencedValues(); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * <p> | |
| * The returned view has the same characteristics as specified for the view | |
| * returned by the {@link #values values} method. | |
| * | |
| * @return {@inheritDoc} | |
| * @since 21 | |
| */ | |
| public SequencedCollection<V> sequencedValues() { | |
| Collection<V> vs = values; | |
| if (vs == null) { | |
| SequencedCollection<V> svs = new LinkedValues(false); | |
| values = svs; | |
| return svs; | |
| } else { | |
| // The cast should never fail, since the only assignment of non-null to values is | |
| // above, and assignments in AbstractMap and HashMap are in overridden methods. | |
| return (SequencedCollection<V>) vs; | |
| } | |
| } | |
| final class LinkedValues extends AbstractCollection<V> implements SequencedCollection<V> { | |
| final boolean reversed; | |
| LinkedValues(boolean reversed) { this.reversed = reversed; } | |
| public final int size() { return size; } | |
| public final void clear() { LinkedHashMap.this.clear(); } | |
| public final Iterator<V> iterator() { | |
| return new LinkedValueIterator(reversed); | |
| } | |
| public final boolean contains(Object o) { return containsValue(o); } | |
| public final Spliterator<V> spliterator() { | |
| return Spliterators.spliterator(this, Spliterator.SIZED | | |
| Spliterator.ORDERED); | |
| } | |
| public Object[] toArray() { | |
| return valuesToArray(new Object[size], reversed); | |
| } | |
| public <T> T[] toArray(T[] a) { | |
| return valuesToArray(prepareArray(a), reversed); | |
| } | |
| public final void forEach(Consumer<? super V> action) { | |
| if (action == null) | |
| throw new NullPointerException(); | |
| int mc = modCount; | |
| if (reversed) { | |
| for (LinkedHashMap.Entry<K,V> e = tail; e != null; e = e.before) | |
| action.accept(e.value); | |
| } else { | |
| for (LinkedHashMap.Entry<K,V> e = head; e != null; e = e.after) | |
| action.accept(e.value); | |
| } | |
| if (modCount != mc) | |
| throw new ConcurrentModificationException(); | |
| } | |
| public final void addFirst(V v) { throw new UnsupportedOperationException(); } | |
| public final void addLast(V v) { throw new UnsupportedOperationException(); } | |
| public final V getFirst() { return nsee(reversed ? tail : head).value; } | |
| public final V getLast() { return nsee(reversed ? head : tail).value; } | |
| public final V removeFirst() { | |
| var node = nsee(reversed ? tail : head); | |
| removeNode(node.hash, node.key, null, false, false); | |
| return node.value; | |
| } | |
| public final V removeLast() { | |
| var node = nsee(reversed ? head : tail); | |
| removeNode(node.hash, node.key, null, false, false); | |
| return node.value; | |
| } | |
| public SequencedCollection<V> reversed() { | |
| if (reversed) { | |
| return LinkedHashMap.this.sequencedValues(); | |
| } else { | |
| return new LinkedValues(true); | |
| } | |
| } | |
| } | |
| /** | |
| * Returns a {@link Set} view of the mappings contained in this map. The encounter | |
| * order of the view matches the encounter order of entries of this map. | |
| * The set is backed by the map, so changes to the map are | |
| * reflected in the set, and vice-versa. If the map is modified | |
| * while an iteration over the set is in progress (except through | |
| * the iterator's own {@code remove} operation, or through the | |
| * {@code setValue} operation on a map entry returned by the | |
| * iterator) the results of the iteration are undefined. The set | |
| * supports element removal, which removes the corresponding | |
| * mapping from the map, via the {@code Iterator.remove}, | |
| * {@code Set.remove}, {@code removeAll}, {@code retainAll} and | |
| * {@code clear} operations. It does not support the | |
| * {@code add} or {@code addAll} operations. | |
| * Its {@link Spliterator} typically provides faster sequential | |
| * performance but much poorer parallel performance than that of | |
| * {@code HashMap}. | |
| * | |
| * @return a set view of the mappings contained in this map | |
| */ | |
| public Set<Map.Entry<K,V>> entrySet() { | |
| return sequencedEntrySet(); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| * <p> | |
| * The returned view has the same characteristics as specified for the view | |
| * returned by the {@link #entrySet entrySet} method. | |
| * | |
| * @return {@inheritDoc} | |
| * @since 21 | |
| */ | |
| public SequencedSet<Map.Entry<K, V>> sequencedEntrySet() { | |
| Set<Map.Entry<K, V>> es = entrySet; | |
| if (es == null) { | |
| SequencedSet<Map.Entry<K, V>> ses = new LinkedEntrySet(false); | |
| entrySet = ses; | |
| return ses; | |
| } else { | |
| // The cast should never fail, since the only assignment of non-null to entrySet is | |
| // above, and assignments in HashMap are in overridden methods. | |
| return (SequencedSet<Map.Entry<K, V>>) es; | |
| } | |
| } | |
| final class LinkedEntrySet extends AbstractSet<Map.Entry<K,V>> | |
| implements SequencedSet<Map.Entry<K,V>> { | |
| final boolean reversed; | |
| LinkedEntrySet(boolean reversed) { this.reversed = reversed; } | |
| public final int size() { return size; } | |
| public final void clear() { LinkedHashMap.this.clear(); } | |
| public final Iterator<Map.Entry<K,V>> iterator() { | |
| return new LinkedEntryIterator(reversed); | |
| } | |
| public final boolean contains(Object o) { | |
| if (!(o instanceof Map.Entry<?, ?> e)) | |
| return false; | |
| Object key = e.getKey(); | |
| Node<K,V> candidate = getNode(key); | |
| return candidate != null && candidate.equals(e); | |
| } | |
| public final boolean remove(Object o) { | |
| if (o instanceof Map.Entry<?, ?> e) { | |
| Object key = e.getKey(); | |
| Object value = e.getValue(); | |
| return removeNode(hash(key), key, value, true, true) != null; | |
| } | |
| return false; | |
| } | |
| public final Spliterator<Map.Entry<K,V>> spliterator() { | |
| return Spliterators.spliterator(this, Spliterator.SIZED | | |
| Spliterator.ORDERED | | |
| Spliterator.DISTINCT); | |
| } | |
| public final void forEach(Consumer<? super Map.Entry<K,V>> action) { | |
| if (action == null) | |
| throw new NullPointerException(); | |
| int mc = modCount; | |
| if (reversed) { | |
| for (LinkedHashMap.Entry<K,V> e = tail; e != null; e = e.before) | |
| action.accept(e); | |
| } else { | |
| for (LinkedHashMap.Entry<K,V> e = head; e != null; e = e.after) | |
| action.accept(e); | |
| } | |
| if (modCount != mc) | |
| throw new ConcurrentModificationException(); | |
| } | |
| final Node<K,V> nsee(Node<K,V> e) { | |
| if (e == null) | |
| throw new NoSuchElementException(); | |
| else | |
| return e; | |
| } | |
| public final void addFirst(Map.Entry<K,V> e) { throw new UnsupportedOperationException(); } | |
| public final void addLast(Map.Entry<K,V> e) { throw new UnsupportedOperationException(); } | |
| public final Map.Entry<K,V> getFirst() { return nsee(reversed ? tail : head); } | |
| public final Map.Entry<K,V> getLast() { return nsee(reversed ? head : tail); } | |
| public final Map.Entry<K,V> removeFirst() { | |
| var node = nsee(reversed ? tail : head); | |
| removeNode(node.hash, node.key, null, false, false); | |
| return node; | |
| } | |
| public final Map.Entry<K,V> removeLast() { | |
| var node = nsee(reversed ? head : tail); | |
| removeNode(node.hash, node.key, null, false, false); | |
| return node; | |
| } | |
| public SequencedSet<Map.Entry<K,V>> reversed() { | |
| if (reversed) { | |
| return LinkedHashMap.this.sequencedEntrySet(); | |
| } else { | |
| return new LinkedEntrySet(true); | |
| } | |
| } | |
| } | |
| // Map overrides | |
| public void forEach(BiConsumer<? super K, ? super V> action) { | |
| if (action == null) | |
| throw new NullPointerException(); | |
| int mc = modCount; | |
| for (LinkedHashMap.Entry<K,V> e = head; e != null; e = e.after) | |
| action.accept(e.key, e.value); | |
| if (modCount != mc) | |
| throw new ConcurrentModificationException(); | |
| } | |
| public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) { | |
| if (function == null) | |
| throw new NullPointerException(); | |
| int mc = modCount; | |
| for (LinkedHashMap.Entry<K,V> e = head; e != null; e = e.after) | |
| e.value = function.apply(e.key, e.value); | |
| if (modCount != mc) | |
| throw new ConcurrentModificationException(); | |
| } | |
| // Iterators | |
| abstract class LinkedHashIterator { | |
| LinkedHashMap.Entry<K,V> next; | |
| LinkedHashMap.Entry<K,V> current; | |
| int expectedModCount; | |
| boolean reversed; | |
| LinkedHashIterator(boolean reversed) { | |
| this.reversed = reversed; | |
| next = reversed ? tail : head; | |
| expectedModCount = modCount; | |
| current = null; | |
| } | |
| public final boolean hasNext() { | |
| return next != null; | |
| } | |
| final LinkedHashMap.Entry<K,V> nextNode() { | |
| LinkedHashMap.Entry<K,V> e = next; | |
| if (modCount != expectedModCount) | |
| throw new ConcurrentModificationException(); | |
| if (e == null) | |
| throw new NoSuchElementException(); | |
| current = e; | |
| next = reversed ? e.before : e.after; | |
| return e; | |
| } | |
| public final void remove() { | |
| Node<K,V> p = current; | |
| if (p == null) | |
| throw new IllegalStateException(); | |
| if (modCount != expectedModCount) | |
| throw new ConcurrentModificationException(); | |
| current = null; | |
| removeNode(p.hash, p.key, null, false, false); | |
| expectedModCount = modCount; | |
| } | |
| } | |
| final class LinkedKeyIterator extends LinkedHashIterator | |
| implements Iterator<K> { | |
| LinkedKeyIterator(boolean reversed) { super(reversed); } | |
| public final K next() { return nextNode().getKey(); } | |
| } | |
| final class LinkedValueIterator extends LinkedHashIterator | |
| implements Iterator<V> { | |
| LinkedValueIterator(boolean reversed) { super(reversed); } | |
| public final V next() { return nextNode().value; } | |
| } | |
| final class LinkedEntryIterator extends LinkedHashIterator | |
| implements Iterator<Map.Entry<K,V>> { | |
| LinkedEntryIterator(boolean reversed) { super(reversed); } | |
| public final Map.Entry<K,V> next() { return nextNode(); } | |
| } | |
| /** | |
| * Creates a new, empty, insertion-ordered LinkedHashMap suitable for the expected number of mappings. | |
| * The returned map uses the default load factor of 0.75, and its initial capacity is | |
| * generally large enough so that the expected number of mappings can be added | |
| * without resizing the map. | |
| * | |
| * @param numMappings the expected number of mappings | |
| * @param <K> the type of keys maintained by the new map | |
| * @param <V> the type of mapped values | |
| * @return the newly created map | |
| * @throws IllegalArgumentException if numMappings is negative | |
| * @since 19 | |
| */ | |
| public static <K, V> LinkedHashMap<K, V> newLinkedHashMap(int numMappings) { | |
| if (numMappings < 0) { | |
| throw new IllegalArgumentException("Negative number of mappings: " + numMappings); | |
| } | |
| return new LinkedHashMap<>(HashMap.calculateHashMapCapacity(numMappings)); | |
| } | |
| // Reversed View | |
| /** | |
| * {@inheritDoc} | |
| * <p> | |
| * Modifications to the reversed view and its map views are permitted and will be | |
| * propagated to this map. In addition, modifications to this map will be visible | |
| * in the reversed view and its map views. | |
| * | |
| * @return {@inheritDoc} | |
| * @since 21 | |
| */ | |
| public SequencedMap<K, V> reversed() { | |
| return new ReversedLinkedHashMapView<>(this); | |
| } | |
| static class ReversedLinkedHashMapView<K, V> extends AbstractMap<K, V> | |
| implements SequencedMap<K, V> { | |
| final LinkedHashMap<K, V> base; | |
| ReversedLinkedHashMapView(LinkedHashMap<K, V> lhm) { | |
| base = lhm; | |
| } | |
| // Object | |
| // inherit toString() from AbstractMap; it depends on entrySet() | |
| public boolean equals(Object o) { | |
| return base.equals(o); | |
| } | |
| public int hashCode() { | |
| return base.hashCode(); | |
| } | |
| // Map | |
| public int size() { | |
| return base.size(); | |
| } | |
| public boolean isEmpty() { | |
| return base.isEmpty(); | |
| } | |
| public boolean containsKey(Object key) { | |
| return base.containsKey(key); | |
| } | |
| public boolean containsValue(Object value) { | |
| return base.containsValue(value); | |
| } | |
| public V get(Object key) { | |
| return base.get(key); | |
| } | |
| public V put(K key, V value) { | |
| return base.put(key, value); | |
| } | |
| public V remove(Object key) { | |
| return base.remove(key); | |
| } | |
| public void putAll(Map<? extends K, ? extends V> m) { | |
| base.putAll(m); | |
| } | |
| public void clear() { | |
| base.clear(); | |
| } | |
| public Set<K> keySet() { | |
| return base.sequencedKeySet().reversed(); | |
| } | |
| public Collection<V> values() { | |
| return base.sequencedValues().reversed(); | |
| } | |
| public Set<Entry<K, V>> entrySet() { | |
| return base.sequencedEntrySet().reversed(); | |
| } | |
| public V getOrDefault(Object key, V defaultValue) { | |
| return base.getOrDefault(key, defaultValue); | |
| } | |
| public void forEach(BiConsumer<? super K, ? super V> action) { | |
| if (action == null) | |
| throw new NullPointerException(); | |
| int mc = base.modCount; | |
| for (LinkedHashMap.Entry<K,V> e = base.tail; e != null; e = e.before) | |
| action.accept(e.key, e.value); | |
| if (base.modCount != mc) | |
| throw new ConcurrentModificationException(); | |
| } | |
| public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) { | |
| if (function == null) | |
| throw new NullPointerException(); | |
| int mc = base.modCount; | |
| for (LinkedHashMap.Entry<K,V> e = base.tail; e != null; e = e.before) | |
| e.value = function.apply(e.key, e.value); | |
| if (base.modCount != mc) | |
| throw new ConcurrentModificationException(); | |
| } | |
| public V putIfAbsent(K key, V value) { | |
| return base.putIfAbsent(key, value); | |
| } | |
| public boolean remove(Object key, Object value) { | |
| return base.remove(key, value); | |
| } | |
| public boolean replace(K key, V oldValue, V newValue) { | |
| return base.replace(key, oldValue, newValue); | |
| } | |
| public V replace(K key, V value) { | |
| return base.replace(key, value); | |
| } | |
| public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) { | |
| return base.computeIfAbsent(key, mappingFunction); | |
| } | |
| public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) { | |
| return base.computeIfPresent(key, remappingFunction); | |
| } | |
| public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) { | |
| return base.compute(key, remappingFunction); | |
| } | |
| public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) { | |
| return base.merge(key, value, remappingFunction); | |
| } | |
| // SequencedMap | |
| public SequencedMap<K, V> reversed() { | |
| return base; | |
| } | |
| public Entry<K, V> firstEntry() { | |
| return base.lastEntry(); | |
| } | |
| public Entry<K, V> lastEntry() { | |
| return base.firstEntry(); | |
| } | |
| public Entry<K, V> pollFirstEntry() { | |
| return base.pollLastEntry(); | |
| } | |
| public Entry<K, V> pollLastEntry() { | |
| return base.pollFirstEntry(); | |
| } | |
| public V putFirst(K k, V v) { | |
| return base.putLast(k, v); | |
| } | |
| public V putLast(K k, V v) { | |
| return base.putFirst(k, v); | |
| } | |
| } | |
| } |