//QueueTestRandom.java
//randomly enqueue and dequeue dummy objects to/from a queue.
//the queue can be bounded or unbounded in size.
//display size of queue at each operation.

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

public class QueueTestRandom {
	
    public static void main(String[] args) {
	String input;
	int userAnswer;
	int queueMaxSize=-1;  //fakeout compiler
	boolean isQueueBounded;

	LinkedList myQueue = new LinkedList();  //create empty queue

        userAnswer = JOptionPane.showConfirmDialog(null,
            "Do you want a bounded size queue?",
	    "",
	    JOptionPane.YES_NO_OPTION);
        if (userAnswer == JOptionPane.YES_OPTION) {
	    input = JOptionPane.showInputDialog("Enter (maximum) size of queue");
	    queueMaxSize = Integer.parseInt( input );
	    isQueueBounded = true;  
	}
	else
	    isQueueBounded = false;  

	do {
	    if (Math.random() < .5)    //enqueue
		if (isQueueBounded && myQueue.size()==queueMaxSize) 
		    System.out.print("overflow");   //does not do overflow
		else 
		    myQueue.addLast(new Object());   //enqueue empty object
	    else                       //dequeue
		if (!myQueue.isEmpty())   //check queue (LinkedList) is not empty
		    myQueue.removeFirst();  //dequeue and discard
		else
		    System.out.print("underflow"); //Queue is empty, nothing to dequeue

	    printQueue( myQueue ); 

	    //slow it down
	    try {
   		Thread.sleep(1000);   //1 s pause
	    }
	    catch (InterruptedException e) {
	    }

	} while (true);

    }
    
    static void printQueue( LinkedList q) {
        for (int i=1; i<=q.size(); i++)
            System.out.print("#");
        System.out.println();
    }
}