Queue Interface

In addition to Collection Operations, Queue interface provides additional operations like returning the Head of the Queue, Retrieving and removing the Head Element of the Queue etc.,

public interface Queue<E> extends Collection<E> {
  boolean offer(E e);
  E remove();
  E poll();
  E element();
  E peek();
}

 

There are many implementations for the Queue interface, LinkedList and PriorityQueue are most useful ones.

Example

   Queue queue1 = new LinkedList();

   Queue queue2 = new PriorityQueue();

Each Queue method exists in two forms:

   1. one throws an exception if the operation fails, and 

   2. the other returns a special value if the operation fails  

  

Operation	Throws exception	Returns special value
Insert	add(e)	offer(e)
Remove	remove()	poll()
Examine	element()	peek()

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