//StackTest.java
//1.generate user-specified number of random ints, push each onto stack, then pop them all off.
//2.loop: randomly push or pop a random int once per second until user wants to stop.

//Stack is one of the built-in classes of the Java Collections Framework.
// It is a list that is only accessed at one end, called the "top"...
// Methods:
//  push(object)    onto top of stack
//  pop()           remove and return object at top of stack
//  peek()          return but don't remove top 
//  empty()         return true if stack is empty
// more... but the push, pop, empty are the definition of a pure stack
//  http://java.sun.com/j2se/1.5.0/docs/api/java/util/Stack.html
//Stack is a subclass of Vector, which is almost the same as an ArrayList,
//so Stack has add, remove, get, iterator etc methods but they usually
//wouldn't be used.
//LinkedList can be used as a stack.  Either its addFirst()/removeFirst() or
//addLast()/removeLast() methods could be used as push and pop.

import java.util.*;     
import javax.swing.*;

class StackTest {
    public static void main(String[] args) {
	String input, userstring;
	int size;
	int range;
	int userAnswer;
	int randInt;
	
	Stack myStack = new Stack();  //**create empty stack 
	
	input = JOptionPane.showInputDialog( "Enter number of random ints to generate" );
	size = Integer.parseInt( input );

	input = JOptionPane.showInputDialog( "Enter upper range of the random ints" );
	range = Integer.parseInt( input );

	System.out.println("Now pushing items onto the stack.");
	printStack(myStack);   //display stack at each step
	for (int i=1; i<=size; i++) {   
	    randInt = (int)(Math.random()*range); 
	    myStack.push(new Integer(randInt));  //*****
	    printStack(myStack);   //display stack at each step
	}

	System.out.println();
	System.out.println("Now popping the items off the stack.");
	printStack(myStack);   //display stack at each step
	while (!myStack.empty()) {
	    System.out.print("popped off: " + myStack.pop() + "\n"); //*****
	    printStack(myStack);   //display stack at each step
	}
	System.out.println();


        userAnswer = JOptionPane.showConfirmDialog(null,
                  "Do you want to do random pushes and pops?",
	          "",
	          JOptionPane.YES_NO_OPTION);
        if (userAnswer == JOptionPane.YES_OPTION) {
	    while (true) {
	        if (Math.random() < .5) {   //push a new random int object
	            randInt = (int)(Math.random()*range);
	            System.out.println("pushing: " + randInt); 
	            myStack.push(new Integer(randInt)); 
	        }
	        else                       //pop
		    if (!myStack.empty())   //check stack is not empty
	                System.out.println("popped off: " + myStack.pop());
		    else
		        System.out.println("underflow"); //stack is empty, nothing to pop

	        printStack( myStack ); 

 	        //slow it down
	        try {
   		    Thread.sleep(1000);   //1000 ms pause
	        }
	        catch (InterruptedException e) {
	        }
            }
        }
        
	System.exit(0);
    }
    
    static void printStack( Stack s) {
	System.out.print("Stack is: ");
        //don't normally iterate over a stack.  here for illustration purposes.
        Iterator items = s.iterator();
        while (items.hasNext())
            System.out.print(items.next()+"  ");
        System.out.println();
    }
}