org.jboss.netty.util.MapBackedSet Maven / Gradle / Ivy
/*
* Copyright 2012 The Netty Project
*
* The Netty Project licenses this file to you 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 org.jboss.netty.util;
import java.io.Serializable;
import java.util.AbstractSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
/**
* A {@link Map}-backed {@link Set}.
*/
final class MapBackedSet extends AbstractSet implements Serializable {
private static final long serialVersionUID = -6761513279741915432L;
private final Map map;
/**
* Creates a new instance which wraps the specified {@code map}.
*/
MapBackedSet(Map map) {
this.map = map;
}
@Override
public int size() {
return map.size();
}
@Override
public boolean contains(Object o) {
return map.containsKey(o);
}
@Override
public boolean add(E o) {
return map.put(o, Boolean.TRUE) == null;
}
@Override
public boolean remove(Object o) {
return map.remove(o) != null;
}
@Override
public void clear() {
map.clear();
}
@Override
public Iterator iterator() {
return map.keySet().iterator();
}
}