com.google.common.collect
Class ForwardingQueue<E>

java.lang.Object
  extended by com.google.common.collect.ForwardingObject
      extended by com.google.common.collect.ForwardingCollection<E>
          extended by com.google.common.collect.ForwardingQueue<E>
All Implemented Interfaces:
Iterable<E>, Collection<E>, Queue<E>
Direct Known Subclasses:
ForwardingBlockingQueue, ForwardingDeque

@GwtCompatible
public abstract class ForwardingQueue<E>
extends ForwardingCollection<E>
implements Queue<E>

A queue which forwards all its method calls to another queue. Subclasses should override one or more methods to modify the behavior of the backing queue as desired per the decorator pattern.

Warning: The methods of ForwardingQueue forward indiscriminately to the methods of the delegate. For example, overriding ForwardingCollection.add(E) alone will not change the behavior of offer(E) which can lead to unexpected behavior. In this case, you should override offer as well, either providing your own implementation, or delegating to the provided standardOffer method.

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

Since:
2.0 (imported from Google Collections Library)
Author:
Mike Bostock, Louis Wasserman

Constructor Summary
protected ForwardingQueue()
          Constructor for use by subclasses.
 
Method Summary
protected abstract  Queue<E> delegate()
          Returns the backing delegate instance that methods are forwarded to.
 E element()
           
 boolean offer(E o)
           
 E peek()
           
 E poll()
           
 E remove()
           
protected  boolean standardOffer(E e)
          A sensible definition of offer(E) in terms of ForwardingCollection.add(E).
protected  E standardPeek()
          A sensible definition of peek() in terms of element().
protected  E standardPoll()
          A sensible definition of poll() in terms of remove().
 
Methods inherited from class com.google.common.collect.ForwardingCollection
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, standardAddAll, standardClear, standardContains, standardContainsAll, standardIsEmpty, standardRemove, standardRemoveAll, standardRetainAll, standardToArray, standardToArray, standardToString, toArray, toArray
 
Methods inherited from class com.google.common.collect.ForwardingObject
toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface java.util.Queue
add
 
Methods inherited from interface java.util.Collection
addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray
 

Constructor Detail

ForwardingQueue

protected ForwardingQueue()
Constructor for use by subclasses.

Method Detail

delegate

protected abstract Queue<E> delegate()
Description copied from class: ForwardingObject
Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet.delegate(). Concrete subclasses override this method to supply the instance being decorated.

Specified by:
delegate in class ForwardingCollection<E>

offer

public boolean offer(E o)
Specified by:
offer in interface Queue<E>

poll

public E poll()
Specified by:
poll in interface Queue<E>

remove

public E remove()
Specified by:
remove in interface Queue<E>

peek

public E peek()
Specified by:
peek in interface Queue<E>

element

public E element()
Specified by:
element in interface Queue<E>

standardOffer

@Beta
protected boolean standardOffer(E e)
A sensible definition of offer(E) in terms of ForwardingCollection.add(E). If you override ForwardingCollection.add(E), you may wish to override offer(E) to forward to this implementation.

Since:
7.0

standardPeek

@Beta
protected E standardPeek()
A sensible definition of peek() in terms of element(). If you override element(), you may wish to override peek() to forward to this implementation.

Since:
7.0

standardPoll

@Beta
protected E standardPoll()
A sensible definition of poll() in terms of remove(). If you override remove(), you may wish to override poll() to forward to this implementation.

Since:
7.0


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