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  /*
   * Copyright (C) 2007 The Guava Authors
   *
   * 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 com.google.common.collect;
 
 
 import java.util.Set;
 
A multiset which forwards all its method calls to another multiset. Subclasses should override one or more methods to modify the behavior of the backing multiset as desired per the decorator pattern.

Warning: The methods of ForwardingMultiset forward indiscriminately to the methods of the delegate. For example, overriding add(java.lang.Object,int) alone will not change the behavior of com.google.common.collect.ForwardingCollection.add(java.lang.Object), which can lead to unexpected behavior. In this case, you should override add(Object) as well, either providing your own implementation, or delegating to the provided standardAdd method.

The standard methods and any collection views they return are not guaranteed to be thread-safe, even when all of the methods that they depend on are thread-safe.

Author(s):
Kevin Bourrillion
Louis Wasserman
Since:
2.0
 
 public abstract class ForwardingMultiset<E> extends ForwardingCollection<E> implements Multiset<E> {

  
Constructor for use by subclasses.
 
   protected ForwardingMultiset() {}
 
   @Override
   protected abstract Multiset<E> delegate();
 
   @Override
   public int count(Object element) {
     return delegate().count(element);
   }
 
   @Override
   public int add(E elementint occurrences) {
     return delegate().add(elementoccurrences);
   }
 
   @Override
   public int remove(Object elementint occurrences) {
     return delegate().remove(elementoccurrences);
   }
 
   @Override
   public Set<E> elementSet() {
     return delegate().elementSet();
   }
 
   @Override
   public Set<Entry<E>> entrySet() {
     return delegate().entrySet();
   }
 
   @Override
   public boolean equals(@Nullable Object object) {
     return object == this || delegate().equals(object);
   }
 
   @Override
   public int hashCode() {
     return delegate().hashCode();
   }
 
   @Override
   public int setCount(E elementint count) {
     return delegate().setCount(elementcount);
   }
 
  public boolean setCount(E elementint oldCountint newCount) {
    return delegate().setCount(elementoldCountnewCount);
  }

  
A sensible definition of com.google.common.collect.ForwardingCollection.contains(java.lang.Object) in terms of count(java.lang.Object). If you override count(java.lang.Object), you may wish to override com.google.common.collect.ForwardingCollection.contains(java.lang.Object) to forward to this implementation.

Since:
7.0
  protected boolean standardContains(@Nullable Object object) {
    return count(object) > 0;
  }

  
A sensible definition of com.google.common.collect.ForwardingCollection.clear() in terms of the iterator method of entrySet(). If you override entrySet(), you may wish to override com.google.common.collect.ForwardingCollection.clear() to forward to this implementation.

Since:
7.0
  protected void standardClear() {
    Iterators.clear(entrySet().iterator());
  }

  
A sensible, albeit inefficient, definition of count(java.lang.Object) in terms of entrySet(). If you override entrySet(), you may wish to override count(java.lang.Object) to forward to this implementation.

Since:
7.0
  @Beta
  protected int standardCount(@Nullable Object object) {
    for (Entry<?> entry : this.entrySet()) {
      if (Objects.equal(entry.getElement(), object)) {
        return entry.getCount();
      }
    }
    return 0;
  }

  
A sensible definition of com.google.common.collect.ForwardingCollection.add(java.lang.Object) in terms of add(java.lang.Object,int). If you override add(java.lang.Object,int), you may wish to override com.google.common.collect.ForwardingCollection.add(java.lang.Object) to forward to this implementation.

Since:
7.0
  protected boolean standardAdd(E element) {
    add(element, 1);
    return true;
  }

  
  @Beta
  protected boolean standardAddAll(Collection<? extends E> elementsToAdd) {
    return Multisets.addAllImpl(thiselementsToAdd);
  }

  
  protected boolean standardRemove(Object element) {
    return remove(element, 1) > 0;
  }

  
A sensible definition of com.google.common.collect.ForwardingCollection.removeAll(java.util.Collection) in terms of the removeAll method of elementSet(). If you override elementSet(), you may wish to override com.google.common.collect.ForwardingCollection.removeAll(java.util.Collection) to forward to this implementation.

Since:
7.0
  protected boolean standardRemoveAll(Collection<?> elementsToRemove) {
    return Multisets.removeAllImpl(thiselementsToRemove);
  }

  
A sensible definition of com.google.common.collect.ForwardingCollection.retainAll(java.util.Collection) in terms of the retainAll method of elementSet(). If you override elementSet(), you may wish to override com.google.common.collect.ForwardingCollection.retainAll(java.util.Collection) to forward to this implementation.

Since:
7.0
  protected boolean standardRetainAll(Collection<?> elementsToRetain) {
    return Multisets.retainAllImpl(thiselementsToRetain);
  }

  
A sensible definition of setCount(java.lang.Object,int) in terms of count(java.lang.Object), add(java.lang.Object,int), and remove(java.lang.Object,int). entrySet(). If you override any of these methods, you may wish to override setCount(java.lang.Object,int) to forward to this implementation.

Since:
7.0
  protected int standardSetCount(E elementint count) {
    return Multisets.setCountImpl(thiselementcount);
  }

  
A sensible definition of setCount(java.lang.Object,int,int) in terms of count(java.lang.Object) and setCount(java.lang.Object,int). If you override either of these methods, you may wish to override setCount(java.lang.Object,int,int) to forward to this implementation.

Since:
7.0
  protected boolean standardSetCount(E elementint oldCountint newCount) {
    return Multisets.setCountImpl(thiselementoldCountnewCount);
  }

  
  @Beta
  protected class StandardElementSet extends Multisets.ElementSet<E> {
    
Constructor for use by subclasses.
    public StandardElementSet() {}
    @Override
    Multiset<E> multiset() {
      return ForwardingMultiset.this;
    }
  }

  
A sensible definition of com.google.common.collect.ForwardingCollection.iterator() in terms of entrySet() and com.google.common.collect.ForwardingCollection.remove(java.lang.Object). If you override either of these methods, you may wish to override com.google.common.collect.ForwardingCollection.iterator() to forward to this implementation.

Since:
7.0
  protected Iterator<E> standardIterator() {
    return Multisets.iteratorImpl(this);
  }

  
A sensible, albeit inefficient, definition of com.google.common.collect.ForwardingCollection.size() in terms of entrySet(). If you override entrySet(), you may wish to override com.google.common.collect.ForwardingCollection.size() to forward to this implementation.

Since:
7.0
  protected int standardSize() {
    return Multisets.sizeImpl(this);
  }

  
A sensible, albeit inefficient, definition of com.google.common.collect.ForwardingCollection.size() in terms of entrySet().size() and count(java.lang.Object). If you override either of these methods, you may wish to override com.google.common.collect.ForwardingCollection.size() to forward to this implementation.

Since:
7.0
  protected boolean standardEquals(@Nullable Object object) {
    return Multisets.equalsImpl(thisobject);
  }

  
A sensible definition of hashCode() as entrySet().hashCode() . If you override entrySet(), you may wish to override hashCode() to forward to this implementation.

Since:
7.0
  protected int standardHashCode() {
    return entrySet().hashCode();
  }

  
A sensible definition of com.google.common.collect.ForwardingObject.toString() as entrySet().toString() . If you override entrySet(), you may wish to override com.google.common.collect.ForwardingObject.toString() to forward to this implementation.

Since:
7.0
  protected String standardToString() {
    return entrySet().toString();
  }
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