package stacks;

import java.util.Stack;
import java.io.PrintWriter;

public class StackExample {
    // class provides a framework for a simple stack example
    // The following steps follow work done in a Scheme lab on Stacks

    public static void main (String args []) 
        throws Exception {

        // Section 0:  Create objects needed later
        //             These stacks may hold any type of Object
        Stack<Object> magPile = new Stack<Object>();
        Stack<Object> billPile = new Stack<Object>();
        PrintWriter out = new PrintWriter(System.out, true);
        out.println ("Section 0 done");
        out.println ("Creation of objects magPile, billPile, and out completed");
        
        // Section 1:  push objects onto billPile
        billPile.push ("mortgage");
        billPile.push ("doctor's bill");
        billPile.push ("credit card");
        out.println ("Section 1 done");
        out.println ("Check if billPile is empty:  " + billPile.isEmpty());
        out.println ("Check if magPile is empty:  "  +  magPile.isEmpty());
        
        // Section 2:  push objects onto magPile
        magPile.push ("Communications of the ACM - April 1997");
        magPile.push ("CS Education Bulletin - Spring 1998");
        out.println ("Section 2 done");
        //Note:  top not a method of built-in class Stack
        //       Replace top() by the appropriate method in what follows!
        //out.println ("Check top of billPile:  " + billPile.top());
        //out.println ("Check top of magPile:  "  +  magPile.top());
        
        // Section 3:  pop and print objects from billPile
        out.println ("Top item removed from billPile:  " + billPile.pop());
        out.println ("Check if billPile is empty:  " + billPile.isEmpty());
        out.println ("Top item removed from billPile:  " + billPile.pop());
        out.println ("Check if billPile is empty:  " + billPile.isEmpty());
        out.println ("Top item removed from billPile:  " + billPile.pop());
        out.println ("Check if billPile is empty:  " + billPile.isEmpty());
        // billPile empty here, so next line causes program to terminate
        out.println ("Top item removed from billPile:  " + billPile.pop());
    }
}