CS401 Lab 8:
A Stack of Objects and a Queue of Objects

Introduction

In this lab you will use inheritance to define a Stack class using the functionality of the Vector class described in the Java APIs. Look at Vector in the Java APIs.

Stack Operations

A Stack implements these operations:

public void push(Object n) adds a new object at the top of the stack.
public Object pop() removes and returns the object from the top of the stack.
public boolean isEmpty() checks if the stack is empty.
public Object top() returns the object from the top of the stack without removing it from the stack.

Assignment

Implement the stack operations in the class Stack in the file Stack.java. Since you are going to define your class in terms of the ElasticArray class, your file should begin with:

           public class Stack { ...



When you are finished, the following program:

  public static void main(String[] args) {

    Stack s = new Stack() ;

    s.push("objects") ;  s.push("on") ;

    s.push("a") ; s.push("stack") ;

    while ( !s.isEmpty() ) { 

      System.out.println( s.pop() ) ; 

    }

prints:

  stack

on

  objects

Queue Operations

A Queue implements these operations:

public void enque(Object n) adds a new object at the rear of the queue.
public Object deque() removes and returns the object from the front of the queue.
public boolean isEmpty() checks if the queue is empty.
public Object peek() returns the object from the front of the queue without removing it from the queue.

  public static void main(String[] args) {

    Queue q = new Queue() ;

    q.enque("objects") ;  q.enque("on") ;

    q.enque("a") ; q.enque("queue") ;

    while ( !q.isEmpty() ) { 

      System.out.println( q.front() ) ; 

      q.deque();

    }