Basics
A Queue is a collection for holding elements prior to processing. Queues typically, but not necessarily, order elements in a FIFO (first-in-first-out) manner.
Head of the queue is the element that would be removed by a call to remove or poll. In a FIFO queue, all new elements are inserted at the tail of the queue.
The Queue Interface
public interface Queue<E> extends Collection<E> {
boolean add(E e);
boolean offer(E e);
E remove();
E poll();
E element();
E peek();
}
Each Queue method exists in two forms:
- one throws an exception if the operation fails;
- other returns a special value if the operation fails (either
null or false depending on the operation.
| Type of operation | Throws exception | Returns special value | | —— | —— |––––| | Insert | add(e) | offer(e) | |Remove|remove()|poll()| |Examine|element()|peek()|
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