diff -r 4252bfc396fc -r d382dacfd73f emul/compact/src/main/java/java/util/HashSet.java --- a/emul/compact/src/main/java/java/util/HashSet.java Tue Feb 26 14:55:55 2013 +0100 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,260 +0,0 @@ -/* - * Copyright (c) 1997, 2010, 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; - -/** - * This class implements the Set interface, backed by a hash table - * (actually a HashMap instance). It makes no guarantees as to the - * iteration order of the set; in particular, it does not guarantee that the - * order will remain constant over time. This class permits the null - * element. - * - *

This class offers constant time performance for the basic operations - * (add, remove, contains and size), - * assuming the hash function disperses the elements properly among the - * buckets. Iterating over this set requires time proportional to the sum of - * the HashSet instance's size (the number of elements) plus the - * "capacity" of the backing HashMap instance (the number of - * buckets). Thus, it's very important not to set the initial capacity too - * high (or the load factor too low) if iteration performance is important. - * - *

Note that this implementation is not synchronized. - * If multiple threads access a hash set concurrently, and at least one of - * the threads modifies the set, it must be synchronized externally. - * This is typically accomplished by synchronizing on some object that - * naturally encapsulates the set. - * - * If no such object exists, the set should be "wrapped" using the - * {@link Collections#synchronizedSet Collections.synchronizedSet} - * method. This is best done at creation time, to prevent accidental - * unsynchronized access to the set:

- *   Set s = Collections.synchronizedSet(new HashSet(...));
- * - *

The iterators returned by this class's iterator method are - * fail-fast: if the set is modified at any time after the iterator is - * created, in any way except through the iterator's own remove - * method, the Iterator throws 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. - * - *

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 ConcurrentModificationException on a best-effort basis. - * Therefore, it would be wrong to write a program that depended on this - * exception for its correctness: the fail-fast behavior of iterators - * should be used only to detect bugs. - * - *

This class is a member of the - * - * Java Collections Framework. - * - * @param the type of elements maintained by this set - * - * @author Josh Bloch - * @author Neal Gafter - * @see Collection - * @see Set - * @see TreeSet - * @see HashMap - * @since 1.2 - */ - -public class HashSet - extends AbstractSet - implements Set, Cloneable, java.io.Serializable -{ - static final long serialVersionUID = -5024744406713321676L; - - private transient HashMap map; - - // Dummy value to associate with an Object in the backing Map - private static final Object PRESENT = new Object(); - - /** - * Constructs a new, empty set; the backing HashMap instance has - * default initial capacity (16) and load factor (0.75). - */ - public HashSet() { - map = new HashMap<>(); - } - - /** - * Constructs a new set containing the elements in the specified - * collection. The HashMap is created with default load factor - * (0.75) and an initial capacity sufficient to contain the elements in - * the specified collection. - * - * @param c the collection whose elements are to be placed into this set - * @throws NullPointerException if the specified collection is null - */ - public HashSet(Collection c) { - map = new HashMap<>(Math.max((int) (c.size()/.75f) + 1, 16)); - addAll(c); - } - - /** - * Constructs a new, empty set; the backing HashMap instance has - * the specified initial capacity and the specified load factor. - * - * @param initialCapacity the initial capacity of the hash map - * @param loadFactor the load factor of the hash map - * @throws IllegalArgumentException if the initial capacity is less - * than zero, or if the load factor is nonpositive - */ - public HashSet(int initialCapacity, float loadFactor) { - map = new HashMap<>(initialCapacity, loadFactor); - } - - /** - * Constructs a new, empty set; the backing HashMap instance has - * the specified initial capacity and default load factor (0.75). - * - * @param initialCapacity the initial capacity of the hash table - * @throws IllegalArgumentException if the initial capacity is less - * than zero - */ - public HashSet(int initialCapacity) { - map = new HashMap<>(initialCapacity); - } - - /** - * Constructs a new, empty linked hash set. (This package private - * constructor is only used by LinkedHashSet.) The backing - * HashMap instance is a LinkedHashMap with the specified initial - * capacity and the specified load factor. - * - * @param initialCapacity the initial capacity of the hash map - * @param loadFactor the load factor of the hash map - * @param dummy ignored (distinguishes this - * constructor from other int, float constructor.) - * @throws IllegalArgumentException if the initial capacity is less - * than zero, or if the load factor is nonpositive - */ - HashSet(int initialCapacity, float loadFactor, boolean dummy) { - map = new LinkedHashMap<>(initialCapacity, loadFactor); - } - - /** - * Returns an iterator over the elements in this set. The elements - * are returned in no particular order. - * - * @return an Iterator over the elements in this set - * @see ConcurrentModificationException - */ - public Iterator iterator() { - return map.keySet().iterator(); - } - - /** - * Returns the number of elements in this set (its cardinality). - * - * @return the number of elements in this set (its cardinality) - */ - public int size() { - return map.size(); - } - - /** - * Returns true if this set contains no elements. - * - * @return true if this set contains no elements - */ - public boolean isEmpty() { - return map.isEmpty(); - } - - /** - * Returns true if this set contains the specified element. - * More formally, returns true if and only if this set - * contains an element e such that - * (o==null ? e==null : o.equals(e)). - * - * @param o element whose presence in this set is to be tested - * @return true if this set contains the specified element - */ - public boolean contains(Object o) { - return map.containsKey(o); - } - - /** - * Adds the specified element to this set if it is not already present. - * More formally, adds the specified element e to this set if - * this set contains no element e2 such that - * (e==null ? e2==null : e.equals(e2)). - * If this set already contains the element, the call leaves the set - * unchanged and returns false. - * - * @param e element to be added to this set - * @return true if this set did not already contain the specified - * element - */ - public boolean add(E e) { - return map.put(e, PRESENT)==null; - } - - /** - * Removes the specified element from this set if it is present. - * More formally, removes an element e such that - * (o==null ? e==null : o.equals(e)), - * if this set contains such an element. Returns true if - * this set contained the element (or equivalently, if this set - * changed as a result of the call). (This set will not contain the - * element once the call returns.) - * - * @param o object to be removed from this set, if present - * @return true if the set contained the specified element - */ - public boolean remove(Object o) { - return map.remove(o)==PRESENT; - } - - /** - * Removes all of the elements from this set. - * The set will be empty after this call returns. - */ - public void clear() { - map.clear(); - } - - /** - * Returns a shallow copy of this HashSet instance: the elements - * themselves are not cloned. - * - * @return a shallow copy of this set - */ - public Object clone() { - try { - HashSet newSet = (HashSet) super.clone(); - newSet.map = (HashMap) map.clone(); - return newSet; - } catch (CloneNotSupportedException e) { - throw new InternalError(); - } - } - -}