| /* |
| * Copyright 2007 Google Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| * use this file except in compliance with the License. You may obtain a copy of |
| * the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| * License for the specific language governing permissions and limitations under |
| * the License. |
| */ |
| package java.util; |
| |
| import java.io.Serializable; |
| |
| /** |
| * Implements a set in terms of a hash table. <a |
| * href="http://java.sun.com/j2se/1.5.0/docs/api/java/util/HashSet.html">[Sun |
| * docs]</a> |
| * |
| * @param <E> element type. |
| */ |
| public class HashSet<E> extends AbstractSet<E> implements Set<E>, Cloneable, |
| Serializable { |
| |
| private transient HashMap<E, Object> map; |
| |
| /** |
| * Ensures that RPC will consider type parameter E to be exposed. It will be |
| * pruned by dead code elimination. |
| */ |
| @SuppressWarnings("unused") |
| private E exposeElement; |
| |
| public HashSet() { |
| map = new HashMap<E, Object>(); |
| } |
| |
| public HashSet(Collection<? extends E> c) { |
| map = new HashMap<E, Object>(c.size()); |
| addAll(c); |
| } |
| |
| public HashSet(int initialCapacity) { |
| map = new HashMap<E, Object>(initialCapacity); |
| } |
| |
| public HashSet(int initialCapacity, float loadFactor) { |
| map = new HashMap<E, Object>(initialCapacity, loadFactor); |
| } |
| |
| /** |
| * Protected constructor to specify the underlying map. This is used by |
| * LinkedHashSet. |
| * |
| * @param map underlying map to use. |
| */ |
| protected HashSet(HashMap<E, Object> map) { |
| this.map = map; |
| } |
| |
| @Override |
| public boolean add(E o) { |
| Object old = map.put(o, this); |
| return (old == null); |
| } |
| |
| @Override |
| public void clear() { |
| map.clear(); |
| } |
| |
| public Object clone() { |
| return new HashSet<E>(this); |
| } |
| |
| @Override |
| public boolean contains(Object o) { |
| return map.containsKey(o); |
| } |
| |
| @Override |
| public boolean isEmpty() { |
| return map.isEmpty(); |
| } |
| |
| @Override |
| public Iterator<E> iterator() { |
| return map.keySet().iterator(); |
| } |
| |
| @Override |
| public boolean remove(Object o) { |
| return (map.remove(o) != null); |
| } |
| |
| @Override |
| public int size() { |
| return map.size(); |
| } |
| |
| } |