001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 * 019 */ 020package org.apache.mina.util; 021 022import java.io.Serializable; 023import java.util.AbstractSet; 024import java.util.Collection; 025import java.util.Iterator; 026import java.util.Map; 027import java.util.Set; 028 029/** 030 * A {@link Map}-backed {@link Set}. 031 * 032 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 033 */ 034public class MapBackedSet<E> extends AbstractSet<E> implements Serializable { 035 036 private static final long serialVersionUID = -8347878570391674042L; 037 038 protected final Map<E, Boolean> map; 039 040 public MapBackedSet(Map<E, Boolean> map) { 041 this.map = map; 042 } 043 044 public MapBackedSet(Map<E, Boolean> map, Collection<E> c) { 045 this.map = map; 046 addAll(c); 047 } 048 049 @Override 050 public int size() { 051 return map.size(); 052 } 053 054 @Override 055 public boolean contains(Object o) { 056 return map.containsKey(o); 057 } 058 059 @Override 060 public Iterator<E> iterator() { 061 return map.keySet().iterator(); 062 } 063 064 @Override 065 public boolean add(E o) { 066 return map.put(o, Boolean.TRUE) == null; 067 } 068 069 @Override 070 public boolean remove(Object o) { 071 return map.remove(o) != null; 072 } 073 074 @Override 075 public void clear() { 076 map.clear(); 077 } 078}