com.google.common.collect

Class ForwardingDeque<E>

java.lang.Object

com.google.common.collect.ForwardingObject

com.google.common.collect.ForwardingCollection<E>

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

com.google.common.collect.ForwardingDeque<E>

All Implemented Interfaces:

Iterable<E>, Collection<E>, Deque<E>, Queue<E>

Direct Known Subclasses:

ForwardingBlockingDeque

public abstract class ForwardingDeque<E>
extends ForwardingQueue<E>
implements Deque<E>

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

Warning: The methods of ForwardingDeque forward indiscriminately to the methods of the delegate. For example, overriding ForwardingCollection.add(E) alone will not change the behavior of ForwardingQueue.offer(E) which can lead to unexpected behavior. In this case, you should override offer as well.

Since:

12.0

Author:

Kurt Alfred Kluever

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ForwardingDeque() Constructor for use by subclasses.

Method Summary

Methods

Modifier and Type	Method and Description
void	addFirst(E e) Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions.
void	addLast(E e) Inserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions.
protected abstract Deque<E>	delegate() Returns the backing delegate instance that methods are forwarded to.
Iterator<E>	descendingIterator() Returns an iterator over the elements in this deque in reverse sequential order.
E	getFirst() Retrieves, but does not remove, the first element of this deque.
E	getLast() Retrieves, but does not remove, the last element of this deque.
boolean	offerFirst(E e) Inserts the specified element at the front of this deque unless it would violate capacity restrictions.
boolean	offerLast(E e) Inserts the specified element at the end of this deque unless it would violate capacity restrictions.
E	peekFirst() Retrieves, but does not remove, the first element of this deque, or returns null if this deque is empty.
E	peekLast() Retrieves, but does not remove, the last element of this deque, or returns null if this deque is empty.
E	pollFirst() Retrieves and removes the first element of this deque, or returns null if this deque is empty.
E	pollLast() Retrieves and removes the last element of this deque, or returns null if this deque is empty.
E	pop() Pops an element from the stack represented by this deque.
void	push(E e) Pushes an element onto the stack represented by this deque (in other words, at the head of this deque) if it is possible to do so immediately without violating capacity restrictions, returning true upon success and throwing an IllegalStateException if no space is currently available.
E	removeFirst() Retrieves and removes the first element of this deque.
boolean	removeFirstOccurrence(Object o) Removes the first occurrence of the specified element from this deque.
E	removeLast() Retrieves and removes the last element of this deque.
boolean	removeLastOccurrence(Object o) Removes the last occurrence of the specified element from this deque.

Methods inherited from class com.google.common.collect.ForwardingQueue

element, offer, peek, poll, remove, standardOffer, standardPeek, standardPoll

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.Deque

add, contains, element, iterator, offer, peek, poll, remove, remove, size

Methods inherited from interface java.util.Collection

addAll, clear, containsAll, equals, hashCode, isEmpty, removeAll, retainAll, toArray, toArray

Constructor Detail

ForwardingDeque

protected ForwardingDeque()

Constructor for use by subclasses.

Method Detail

delegate

protected abstract Deque<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 ForwardingQueue<E>

addFirst

public void addFirst(E e)

Description copied from interface: java.util.Deque

Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions. When using a capacity-restricted deque, it is generally preferable to use method Deque.offerFirst(E).

Specified by:

addFirst in interface Deque<E>

Parameters:

e - the element to add

addLast

public void addLast(E e)

Description copied from interface: java.util.Deque

Inserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions. When using a capacity-restricted deque, it is generally preferable to use method Deque.offerLast(E).

This method is equivalent to Deque.add(E).

Specified by:

addLast in interface Deque<E>

Parameters:

e - the element to add

descendingIterator

public Iterator<E> descendingIterator()

Description copied from interface: java.util.Deque

Returns an iterator over the elements in this deque in reverse sequential order. The elements will be returned in order from last (tail) to first (head).

Specified by:

descendingIterator in interface Deque<E>

Returns:

an iterator over the elements in this deque in reverse sequence

getFirst

public E getFirst()

Description copied from interface: java.util.Deque

Retrieves, but does not remove, the first element of this deque. This method differs from peekFirst only in that it throws an exception if this deque is empty.

Specified by:

getFirst in interface Deque<E>

Returns:

the head of this deque

getLast

public E getLast()

Description copied from interface: java.util.Deque

Retrieves, but does not remove, the last element of this deque. This method differs from peekLast only in that it throws an exception if this deque is empty.

Specified by:

getLast in interface Deque<E>

Returns:

the tail of this deque

offerFirst

public boolean offerFirst(E e)

Description copied from interface: java.util.Deque

Inserts the specified element at the front of this deque unless it would violate capacity restrictions. When using a capacity-restricted deque, this method is generally preferable to the Deque.addFirst(E) method, which can fail to insert an element only by throwing an exception.

Specified by:

offerFirst in interface Deque<E>

Parameters:

e - the element to add

Returns:

true if the element was added to this deque, else false

offerLast

public boolean offerLast(E e)

Description copied from interface: java.util.Deque

Inserts the specified element at the end of this deque unless it would violate capacity restrictions. When using a capacity-restricted deque, this method is generally preferable to the Deque.addLast(E) method, which can fail to insert an element only by throwing an exception.

Specified by:

offerLast in interface Deque<E>

Parameters:

e - the element to add

Returns:

true if the element was added to this deque, else false

peekFirst

public E peekFirst()

Description copied from interface: java.util.Deque

Retrieves, but does not remove, the first element of this deque, or returns null if this deque is empty.

Specified by:

peekFirst in interface Deque<E>

Returns:

the head of this deque, or null if this deque is empty

peekLast

public E peekLast()

Description copied from interface: java.util.Deque

Retrieves, but does not remove, the last element of this deque, or returns null if this deque is empty.

Specified by:

peekLast in interface Deque<E>

Returns:

the tail of this deque, or null if this deque is empty

pollFirst

public E pollFirst()

Description copied from interface: java.util.Deque

Retrieves and removes the first element of this deque, or returns null if this deque is empty.

Specified by:

pollFirst in interface Deque<E>

Returns:

the head of this deque, or null if this deque is empty

pollLast

public E pollLast()

Description copied from interface: java.util.Deque

Retrieves and removes the last element of this deque, or returns null if this deque is empty.

Specified by:

pollLast in interface Deque<E>

Returns:

the tail of this deque, or null if this deque is empty

pop

public E pop()

Description copied from interface: java.util.Deque

Pops an element from the stack represented by this deque. In other words, removes and returns the first element of this deque.

This method is equivalent to Deque.removeFirst().

Specified by:

pop in interface Deque<E>

Returns:

the element at the front of this deque (which is the top of the stack represented by this deque)

push

public void push(E e)

Description copied from interface: java.util.Deque

Pushes an element onto the stack represented by this deque (in other words, at the head of this deque) if it is possible to do so immediately without violating capacity restrictions, returning true upon success and throwing an IllegalStateException if no space is currently available.

This method is equivalent to Deque.addFirst(E).

Specified by:

push in interface Deque<E>

Parameters:

e - the element to push

removeFirst

public E removeFirst()

Description copied from interface: java.util.Deque

Retrieves and removes the first element of this deque. This method differs from pollFirst only in that it throws an exception if this deque is empty.

Specified by:

removeFirst in interface Deque<E>

Returns:

the head of this deque

removeLast

public E removeLast()

Description copied from interface: java.util.Deque

Retrieves and removes the last element of this deque. This method differs from pollLast only in that it throws an exception if this deque is empty.

Specified by:

removeLast in interface Deque<E>

Returns:

the tail of this deque

removeFirstOccurrence

public boolean removeFirstOccurrence(Object o)

Description copied from interface: java.util.Deque

Removes the first occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the first element e such that (o==null ? e==null : o.equals(e)) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).

Specified by:

removeFirstOccurrence in interface Deque<E>

Parameters:

o - element to be removed from this deque, if present

Returns:

true if an element was removed as a result of this call

removeLastOccurrence

public boolean removeLastOccurrence(Object o)

Description copied from interface: java.util.Deque

Removes the last occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the last element e such that (o==null ? e==null : o.equals(e)) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).

Specified by:

removeLastOccurrence in interface Deque<E>

Parameters:

o - element to be removed from this deque, if present

Returns:

true if an element was removed as a result of this call