Interface QueueInterface<E>

Type Parameters:

E - The type of Object that the queue will accept.

All Superinterfaces:

java.lang.Iterable<E>

All Known Implementing Classes:

ArrayBasedQueue, LinkedQueue

public interface QueueInterface<E>
extends java.lang.Iterable<E>

Generic interface for a FIFO queue.

Author:

Sameh Fakhouri

Method Summary

Modifier and Type	Method and Description
E	dequeue() Retrieves and removes the element at the head of this queue.
E	dequeue(int index) Retrieves and removes the element at the specified index.
void	enqueue(E e) Adds the specified element into the stack if it is possible to do so immediately without violating capacity restrictions, otherwise, throwing an IllegalStateException if no space is currently available or NullPointerException if the specified element is null.
boolean	isEmpty() This method is called to determine if the queue is empty.
E	peek() Retrieves, but does not remove, the head of this queue.
void	removeAll() Removes all elements from the queue.
int	size() This method is called to obtain the count of elements in the list.

Methods inherited from interface java.lang.Iterable

forEach, iterator, spliterator

Method Detail

isEmpty

boolean isEmpty()

This method is called to determine if the queue is empty.

Returns:

Returns true if the queue is empty, otherwise it returns false.

size

int size()

This method is called to obtain the count of elements in the list.

Returns:

Returns the numbers of elements that are currently in the queue.

enqueue

void enqueue(E e)
      throws java.lang.IllegalStateException,
             java.lang.NullPointerException

Adds the specified element into the stack if it is possible to do so immediately without violating capacity restrictions, otherwise, throwing an IllegalStateException if no space is currently available or NullPointerException if the specified element is null.

Parameters:

e - The element to add.

Throws:

java.lang.IllegalStateException - If the element cannot be added at this time due to capacity restrictions.

java.lang.NullPointerException - If the specified element being added is null.

peek

E peek()

Retrieves, but does not remove, the head of this queue.

Returns:

The element at the head of the queue or null if the queue is empty.

dequeue

E dequeue()

Retrieves and removes the element at the head of this queue.

Returns:

The element at the head of the queue or null if the queue is empty.

dequeue

E dequeue(int index)
   throws java.util.NoSuchElementException

Retrieves and removes the element at the specified index.

Parameters:

index - The index of the element to be removed.

Returns:

The element at the specified index.

Throws:

java.util.NoSuchElementException - If the specified index is invalid.

removeAll

void removeAll()

Removes all elements from the queue.