/*
	Demonstration of Stack
	
	
	author: 
	course: 15-111 Java Programming 
	section: 
	date: 	

*/

import java.io.*;
import java.util.*;

public class Stack 
     {
      
         // default constructor
         public Stack () {V = new Vector();} 
        // accessors
         public boolean empty(){ return (V.size()==0);}
         public boolean full(){return false;} 
         public Object  topOfStack() {
             return (V.elementAt(V.size()-1));
         }// returns the top value of the stack
         public int   sizeOfStack() { return V.size() ;}      // returns the size of the stack 
         // mutators
         // push a value to the top of the stack
         public void push(Object x){V.add(x);} 
         public Object pop(){
            if (!empty())
              { Object temp = V.elementAt(V.size()-1);
                V.remove(V.size()-1);
                return temp;
              }
            else
               return null;    
         
         }    	     // remove the most recent item
         public void clear(){
            while (!empty()) pop();
         
         }                // clear the entire stack
         public void print(){
           for (int i=V.size()-1; i>=0;i--)
             System.out.println(((Integer)V.elementAt(i)).intValue());
         
         }
         private Vector V;  // is a pointer to the top element of the stack
         
    
   


}