COLASQUIZ

// QueueDemo.java

import com.javajeff.cds.*;

class QueueDemo {
public static void main (String [] args) {
System.out.println ("ArrayLinearQueue Demo");
System.out.println ("---------------------");
queueDemo (new ArrayLinearQueue (5));
System.out.println ("ArrayCircularQueue Demo");
System.out.println ("---------------------");
queueDemo (new ArrayCircularQueue (6)); // Need one more slot because
// of empty slot in circular
// implementation
}

static void queueDemo (Queue q) {
System.out.println ("Is empty = " + q.isEmpty ());
System.out.println ("Is full = " + q.isFull ());

System.out.println ("Inserting \"This\"");
q.insert ("This");

System.out.println ("Inserting \"is\"");
q.insert ("is");

System.out.println ("Inserting \"a\"");
q.insert ("a");

System.out.println ("Inserting \"sentence\"");
q.insert ("sentence");

System.out.println ("Inserting \".\"");
q.insert (".");

try {
System.out.println ("Inserting \"One last item\"");
q.insert ("One last item");
}
catch (FullQueueException e) {
System.out.println ("One insert too many");
System.out.println ("Is empty = " + q.isEmpty ());
System.out.println ("Is full = " + q.isFull ());
}

System.out.println ();

while (!q.isEmpty ())
System.out.println (q.remove () + " [Is empty = " + q.isEmpty () +
", Is full = " + q.isFull () + "]");

try {
q.remove ();
}
catch (EmptyQueueException e) {
System.out.println ("One remove too many");
}
System.out.println ();
}
}
************************
// ArrayLinearQueue.java

package com.javajeff.cds;

public class ArrayLinearQueue implements Queue {
private int front = -1, rear = -1;
private Object [] queue;

public ArrayLinearQueue (int maxElements) {
queue = new Object [maxElements];
}

public void insert (Object o) {
if (rear == queue.length - 1)
throw new FullQueueException ();
queue [++rear] = o;
}

public boolean isEmpty () {
return front == rear;
}

public boolean isFull () {
return rear == queue.length - 1;
}

public Object remove () {
if (front == rear)
throw new EmptyQueueException ();
return queue [++front];
}
}

*****************
// ArrayCircularQueue.java

package com.javajeff.cds;

public class ArrayCircularQueue implements Queue {
private int front = 0, rear = 0;
private Object [] queue;

public ArrayCircularQueue (int maxElements) {
queue = new Object [maxElements];
}

public void insert (Object o) {
int temp = rear;
rear = (rear + 1) % queue.length;
if (front == rear) {
rear = temp;
throw new FullQueueException ();
}
queue [rear] = o;
}

public boolean isEmpty () {
return front == rear;
}

public boolean isFull () {
return ((rear + 1) % queue.length) == front;
}

public Object remove () {
if (front == rear)
throw new EmptyQueueException ();
front = (front + 1) % queue.length;
return queue [front];
}
}


**************************
// Queue.java

package com.javajeff.cds;

public interface Queue {
void insert (Object o);
boolean isEmpty ();
boolean isFull ();
Object remove ();
}


****************************
// FullQueueException.java

package com.javajeff.cds;

public class FullQueueException extends RuntimeException {

/**
*
*/
private static final long serialVersionUID = 1L;
}


***********************
// EmptyQueueException.java

package com.javajeff.cds;

public class EmptyQueueException extends RuntimeException {

/**
*
*/
private static final long serialVersionUID = 1L;
}