Package com.google.common.collect

Class ForwardingDeque<E>

  • All Implemented Interfaces:
    <E>, <E>, <E>, <E>
    Direct Known Subclasses:
    ForwardingBlockingDeque, ForwardingBlockingDeque
    @GwtIncompatible
public abstract class ForwardingDeque<E>
extends ForwardingQueue<E>
implements <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 .

    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.

    default method warning: This class does not forward calls to default methods. Instead, it inherits their default implementations. When those implementations invoke methods, they invoke methods on the ForwardingDeque.

    Since:
    12.0
    Author:
    Kurt Alfred Kluever

    • Constructor Summary

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

    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method 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, throwing an IllegalStateException if no space is currently available.
      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, throwing an IllegalStateException if no space is currently available.
      protected abstract <E> delegate()
      Returns the backing delegate instance that methods are forwarded to.
      <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, throwing an IllegalStateException if no space is currently available.
      E removeFirst()
      Retrieves and removes the first element of this deque.
      boolean  o)
      Removes the first occurrence of the specified element from this deque.
      E removeLast()
      Retrieves and removes the last element of this deque.
      boolean  o)
      Removes the last occurrence of the specified element from this deque.

      • Methods inherited from class java.lang.

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      • Methods inherited from interface java.util.

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      • Methods inherited from interface java.util.

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      • Methods inherited from interface java.lang.

    • Constructor Detail

      • ForwardingDeque

        protected ForwardingDeque()
        Constructor for use by subclasses.

    • Method Detail

      • delegate

        protected abstract <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: 
        Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions, throwing an IllegalStateException if no space is currently available. When using a capacity-restricted deque, it is generally preferable to use method .
        Specified by:
         in interface <E>
        Parameters:
        e - the element to add

      • addLast

        public void addLast​(E e)
        Description copied from interface: 
        Inserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions, throwing an IllegalStateException if no space is currently available. When using a capacity-restricted deque, it is generally preferable to use method .

        This method is equivalent to .

        Specified by:
         in interface <E>
        Parameters:
        e - the element to add

      • descendingIterator

        public <E> descendingIterator()
        Description copied from interface: 
        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:
         in interface <E>
        Returns:
        an iterator over the elements in this deque in reverse sequence

      • getFirst

        public E getFirst()
        Description copied from interface: 
        Retrieves, but does not remove, the first element of this deque. This method differs from only in that it throws an exception if this deque is empty.
        Specified by:
         in interface <E>
        Returns:
        the head of this deque

      • getLast

        public E getLast()
        Description copied from interface: 
        Retrieves, but does not remove, the last element of this deque. This method differs from only in that it throws an exception if this deque is empty.
        Specified by:
         in interface <E>
        Returns:
        the tail of this deque

      • offerFirst

        public boolean offerFirst​(E e)
        Description copied from interface: 
        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 method, which can fail to insert an element only by throwing an exception.
        Specified by:
         in interface <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: 
        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 method, which can fail to insert an element only by throwing an exception.
        Specified by:
         in interface <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: 
        Retrieves, but does not remove, the first element of this deque, or returns null if this deque is empty.
        Specified by:
         in interface <E>
        Returns:
        the head of this deque, or null if this deque is empty

      • peekLast

        public E peekLast()
        Description copied from interface: 
        Retrieves, but does not remove, the last element of this deque, or returns null if this deque is empty.
        Specified by:
         in interface <E>
        Returns:
        the tail of this deque, or null if this deque is empty

      • pollFirst

        public E pollFirst()
        Description copied from interface: 
        Retrieves and removes the first element of this deque, or returns null if this deque is empty.
        Specified by:
         in interface <E>
        Returns:
        the head of this deque, or null if this deque is empty

      • pollLast

        public E pollLast()
        Description copied from interface: 
        Retrieves and removes the last element of this deque, or returns null if this deque is empty.
        Specified by:
         in interface <E>
        Returns:
        the tail of this deque, or null if this deque is empty

      • pop

        public E pop()
        Description copied from interface: 
        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 .

        Specified by:
         in interface <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: 
        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, throwing an IllegalStateException if no space is currently available.

        This method is equivalent to .

        Specified by:
         in interface <E>
        Parameters:
        e - the element to push

      • removeFirst

        public E removeFirst()
        Description copied from interface: 
        Retrieves and removes the first element of this deque. This method differs from only in that it throws an exception if this deque is empty.
        Specified by:
         in interface <E>
        Returns:
        the head of this deque

      • removeLast

        public E removeLast()
        Description copied from interface: 
        Retrieves and removes the last element of this deque. This method differs from only in that it throws an exception if this deque is empty.
        Specified by:
         in interface <E>
        Returns:
        the tail of this deque

      • removeFirstOccurrence

        public boolean  o)
        Description copied from interface: 
        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 Objects.equals(o, 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:
         in interface <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  o)
        Description copied from interface: 
        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 Objects.equals(o, 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:
         in interface <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