structure
Class AbstractQueue

java.lang.Object
  |
  +--structure.AbstractStructure
        |
        +--structure.AbstractLinear
              |
              +--structure.AbstractQueue

All Implemented Interfaces:

Linear, Queue, Structure

Direct Known Subclasses:

QueueArray, QueueList, QueueVector

public abstract class AbstractQueue

extends AbstractLinear

implements Queue

An abstract structure implementing features common to all first-in, first-out structures in this package. Queues are typically used to process values in the order that they appear and to store the state of buffered objects. The structure package provides several implementations of the Queue interface, each of which has its particular strengths and weaknesses.

Example usage:

To compute the sum of the unicode value of every character in the standard input we could use the following:

 public static void main(String[] arguments)
 {
     AbstractQueue q = new QueueList();
     int unicodeSum = 0;

     if(arguments.length > 0){
         for(int i=0; i < arguments.length; i++){
	       for(int j=0; j < arguments[i].length(); j++){
		   q.enqueue(new Character(arguments[i].charAt(j)));
	       }
	   }
     }

     while(!q.AbstractLinear.empty()){
	  char c = ((Character)q.dequeue()).charValue();
	  unicodeSum+=Character.getNumericValue(c);
     }

     System.out.println("Total Value: " + unicodeSum);
 }
 

See Also:

QueueArray, QueueVector, QueueList

Constructor Summary

AbstractQueue()

Method Summary

Object	dequeue() Remove a value form the head of the queue.
void	enqueue(Object item) Add a value to the tail of the queue.
Object	getFirst() Fetch the value at the head of the queue.
Object	peek() Fetch the value at the head of the queue.

Methods inherited from class structure.AbstractLinear

empty, remove

Methods inherited from class structure.AbstractStructure

contains, elements, hashCode, isEmpty, values

Methods inherited from class java.lang.Object

, clone, equals, finalize, getClass, notify, notifyAll, registerNatives, toString, wait, wait, wait

Methods inherited from interface structure.Queue

add, empty, get, remove, size

Methods inherited from interface structure.Structure

clear, contains, elements, isEmpty, iterator, remove, values

Constructor Detail

AbstractQueue

public AbstractQueue()

Method Detail

enqueue

public void enqueue(Object item)

Add a value to the tail of the queue.

Specified by:

enqueue in interface Queue

Parameters:

value - The value added.

Postcondition:

the value is added to the tail of the structure

dequeue

public Object dequeue()

Remove a value form the head of the queue.

Specified by:

dequeue in interface Queue

Precondition:

the queue is not empty

Postcondition:

the head of the queue is removed and returned

Returns:

The value actually removed.

getFirst

public Object getFirst()

Fetch the value at the head of the queue.

Specified by:

getFirst in interface Queue

Precondition:

the queue is not empty

Postcondition:

the element at the head of the queue is returned

Returns:

Reference to the first value of the queue.

peek

public Object peek()

Fetch the value at the head of the queue.

Specified by:

peek in interface Queue

Precondition:

the queue is not empty

Postcondition:

the element at the head of the queue is returned

Returns:

Reference to the first value of the queue.