001    /*
002     * Copyright (C) 2007 Google Inc.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    
017    package com.google.common.collect;
018    
019    import com.google.common.annotations.GwtCompatible;
020    
021    import java.util.Collection;
022    import java.util.Iterator;
023    
024    /**
025     * A collection which forwards all its method calls to another collection.
026     * Subclasses should override one or more methods to modify the behavior of
027     * the backing collection as desired per the <a
028     * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
029     *
030     * @author Kevin Bourrillion
031     * @since 2 (imported from Google Collections Library)
032     */
033    @GwtCompatible
034    public abstract class ForwardingCollection<E> extends ForwardingObject
035        implements Collection<E> {
036    
037      /** Constructor for use by subclasses. */
038      protected ForwardingCollection() {}
039    
040      @Override protected abstract Collection<E> delegate();
041    
042      public Iterator<E> iterator() {
043        return delegate().iterator();
044      }
045    
046      public int size() {
047        return delegate().size();
048      }
049    
050      public boolean removeAll(Collection<?> collection) {
051        return delegate().removeAll(collection);
052      }
053    
054      public boolean isEmpty() {
055        return delegate().isEmpty();
056      }
057    
058      public boolean contains(Object object) {
059        return delegate().contains(object);
060      }
061    
062      public Object[] toArray() {
063        return delegate().toArray();
064      }
065    
066      public <T> T[] toArray(T[] array) {
067        return delegate().toArray(array);
068      }
069    
070      public boolean add(E element) {
071        return delegate().add(element);
072      }
073    
074      public boolean remove(Object object) {
075        return delegate().remove(object);
076      }
077    
078      public boolean containsAll(Collection<?> collection) {
079        return delegate().containsAll(collection);
080      }
081    
082      public boolean addAll(Collection<? extends E> collection) {
083        return delegate().addAll(collection);
084      }
085    
086      public boolean retainAll(Collection<?> collection) {
087        return delegate().retainAll(collection);
088      }
089    
090      public void clear() {
091        delegate().clear();
092      }
093    }