barbershopapplet.java

Barber Shop algorithm Synchronization Simulator

/* File: BarberShopApplet.java
 *
 * This is a Java applet file for Barbershop problem animation. The GUI
 * of this applet contains three parts: animation canvas, message canvas
 * and a button panel.
 * The animation canvas is where the Barbershop animation is displayed.
 * The message canvas is where the statues of barbers and customers are displayed.
 * The button panel has 6 basic buttons: START, STOP, PAUSE, CONTINUE, FASTER,
 * SLOWER.
 *
 * This applet will allow user to choose from a fair barbershop or unfair barbershop.
 * In the fair barbershop, unless the user choose the number of customers, default
 * number of the customers is 4.
 * The number of customers in the unfair barbershop is also 4. And there are two
 * unfair situations that the user can choose from.
 *
 *
 * @author:      Jie Zhang
 * Last Updated: 07/19/2002
 */


import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.applet.Applet;
import java.lang.*;

public class BarberShopApplet extends Applet
{
	private BarberShopApplet applet = this;
	private BarberShop myShop;
	private Button fastButton, slowButton, stopButton, startButton,pauseButton, continueButton;
	private Panel buttonPanel, namePanel, namePanel2;
	private Checkbox haltResource, requestResource;
	private Choice customer;
	private int customerN = 4;		//default number of customer and barber
	private int barberN   = 3;
	private Thread at;
	MessageCanvas mc;
	Customer[] c;
	Barber[] b;
	int haltFlag	 = 0;
	int requestFlag  = 0;
	synchronized void startPushed() {notify();}
	synchronized void stopPushed()  {notify();}

	public void init() {
		resize(800, 600);
		setLayout(new GridLayout(3, 1));

		myShop = new BarberShop();
		mc = new MessageCanvas();
		add(myShop);						//add BarberShop canvas at the top
		add(mc);							//add message box canvas in the middle

		buttonPanel = new Panel();
		Panel namePanel = new Panel();
		Panel bPanel = new Panel(); 		// to hold all buttons and the labels
		bPanel.setFont(new Font("TimesRoman", Font.BOLD, 14));
		bPanel.setLayout(new GridLayout(3, 1));

		buttonPanel.add(startButton 	= new Button("START"));
		buttonPanel.add(stopButton 		= new Button("STOP"));
		buttonPanel.add(pauseButton 	= new Button("PAUSE"));
		buttonPanel.add(continueButton 	= new Button("CONTINUE"));
		buttonPanel.add(fastButton 		= new Button("FAST"));
		buttonPanel.add(slowButton 		= new Button("SLOW"));

		Label titleLabel = new Label("Fair Barbershop", Label.CENTER);
		titleLabel.setFont(new Font("TimesRoman", Font.BOLD, 16));
		titleLabel.setForeground(Color.blue);
		Label textLabel = new Label("Maximum Shop Capacity is 8 Customers", Label.CENTER);

		Label titleLabel2 = new Label("Unfair Barbershop ", Label.CENTER);
		Label textLabel2 = new Label("4 Customers In The Shop", Label.CENTER);
		titleLabel2.setFont(new Font("TimesRoman", Font.BOLD, 16));
		titleLabel2.setForeground(Color.blue);

		namePanel.setLayout(new GridLayout(2,1));
		namePanel.add(titleLabel);
		namePanel.add(textLabel);

		namePanel2 = new Panel();
		namePanel2.setLayout(new GridLayout(2,1));
		namePanel2.add(titleLabel2);
		namePanel2.add(textLabel2);

		Panel titlePanel = new Panel();
		titlePanel.setLayout(new GridLayout(1,2));
		titlePanel.add(namePanel);
		titlePanel.add(namePanel2);

		Panel choicePanel = new Panel();    //to hold all the choice boxes
		choicePanel.setLayout(new GridLayout(1,2));
		customer = new Choice();
		for(int i = 1; i <=10; i++)
		{
			customer.addItem(Integer.toString(i));
		}
		customer.select("4");
		Label customerLabel = new Label("Number of Customers", 2);
		customerLabel.setBackground(Color.lightGray);
		Panel customerPanel = new Panel();
		customerPanel.add(customerLabel);
		customerPanel.add(customer);

		Panel unfairPanel = new Panel();
		unfairPanel.setLayout(new GridLayout(2,1));
		CheckboxGroup g = new CheckboxGroup();
		unfairPanel.add(haltResource = new Checkbox("Request finished, but resources are held unnecessarily", g, false));
		unfairPanel.add(requestResource = new Checkbox("Request not finished, but resources are released", g, false));
		choicePanel.add(customerPanel);
		choicePanel.add(unfairPanel);

		bPanel.add(titlePanel);
		bPanel.add(choicePanel);
		bPanel.add(buttonPanel);

		add(bPanel);
	}

	public boolean action(Event evt, Object arg)
	{
		if(evt.target == customer)
		{
			customerN = Integer.parseInt(arg.toString());
			haltResource.setEnabled(false);
			requestResource.setEnabled(false);
			return true;
		}
		else if(evt.target == haltResource)
		{
			startButton.setEnabled(false);
			customer.setEnabled(false);
			stopButton.setEnabled(true);
			haltResource.setEnabled(false);
			requestResource.setEnabled(false);
			haltFlag = 1;
			System.out.println("HaltResource");
			customerN = 4;
			myShop.setSize(customerN);
			c = new Customer[customerN+1];		//Customer[0] is a dummy slot
			b = new Barber[barberN+1];

			mc.setMessage(barberN, customerN);
			for(int i = 1; i <= customerN; i++)
			{
				c[i] = new Customer(applet, myShop, i);
			}

			for(int i = 1; i <= barberN; i++)
			{
				b[i] = new Barber(applet, myShop, i);
			}
			for(int i = 1; i <= barberN; i++)
			{
				b[i].start();
			}
			for(int i = 1; i <= customerN; i++)
			{
				c[i].start();
			}

			return true;
		}
		else if(evt.target == requestResource)
		{
			startButton.setEnabled(false);
			stopButton.setEnabled(true);
			customer.setEnabled(false);
			haltResource.setEnabled(false);
			requestResource.setEnabled(false);
			System.out.println("RequestResource");
			requestFlag = 1;

			customerN = 4;
			myShop.setSize(customerN);
			c = new Customer[customerN+1];		//Customer[0] is a dummy slot
			b = new Barber[barberN+1];

			mc.setMessage(barberN, customerN);
			for(int i = 1; i <= customerN; i++)
			{
				c[i] = new Customer(applet, myShop, i);
			}

			for(int i = 1; i <= barberN; i++)
			{
				b[i] = new Barber(applet, myShop, i);
			}
			for(int i = 1; i <= barberN; i++)
			{
				b[i].start();
			}
			for(int i = 1; i <= customerN; i++)
			{
				c[i].start();
			}

			return true;
		}
		else if(arg.equals("PAUSE"))
		{	for(int i = 1; i <= customerN; i++)
			{
				if(c[i].isAlive()) 	c[i].suspend();
			}
			for(int i = 1; i <= barberN; i++)
			{
				if(b[i].isAlive())	b[i].suspend();
			}
			fastButton.setEnabled(false);
			slowButton.setEnabled(false);
			return true;
		}
		else if(arg.equals("CONTINUE"))
		{
			for(int i = 1; i <= customerN; i++)
			{
				if(c[i].isAlive()) 	c[i].resume();
			}

			for(int i = 1; i <= barberN; i++)
			{
				if(b[i].isAlive())	b[i].resume();
			}
			fastButton.setEnabled(true);
			slowButton.setEnabled(true);
			return true;
		}
		else if(arg.equals("FASTER"))
		{
			int newDelay = b[1].delay;
			newDelay /= 2;
			newDelay = newDelay < 100 ? 100: newDelay;

			for(int i = 1; i <= customerN; i++)
			{
					c[i].delay = newDelay;
			}
			for(int i = 1; i <= barberN; i++)
			{
					b[i].delay = newDelay;
			}
			return true;
		}
		else if(arg.equals("SLOWER"))
		{
			int newDelay = b[1].delay;
			newDelay *= 2;
			for(int i = 1; i <= customerN; i++)
			{
				c[i].delay = newDelay;
			}
			for(int i = 1; i <= barberN; i++)
			{
				b[i].delay = newDelay;
			}
			return true;
		}
		else if(arg.equals("START"))
		{
			myShop.setSize(customerN);
			c = new Customer[customerN+1];		//Customer[0] is a dummy slot
			b = new Barber[barberN+1];

			mc.setMessage(barberN, customerN);
			for(int i = 1; i <= customerN; i++)
			{
				c[i] = new Customer(applet, myShop, i);
			}

			for(int i = 1; i <= barberN; i++)
			{
				b[i] = new Barber(applet, myShop, i);
			}
			for(int i = 1; i <= barberN; i++)
			{
				b[i].start();
			}
			for(int i = 1; i <= customerN; i++)
			{
				c[i].start();
			}

			applet.startPushed();
			stopButton.setEnabled(true);
			startButton.setEnabled(false);
			fastButton.setEnabled(true);
			slowButton.setEnabled(true);
			customer.setEnabled(false);
			haltResource.setEnabled(false);
			requestResource.setEnabled(false);
			return true;
		}

		else if(arg.equals("STOP"))
		{
			try{
				for(int i = 1; i <= customerN; i++)
				{
					if(c[i].isAlive()) 	c[i].stop();
					c[i] = null;
				}

				for(int i = 1; i <= barberN; i++)
				{
					if(b[i].isAlive()) 	b[i].stop();
					b[i] = null;
				}
				}catch(Exception e) {}

			myShop.clear();
			applet.stopPushed();
			haltFlag 	= 0;
			requestFlag = 0;
			startButton.setEnabled(true);
			customer.setEnabled(true);
			haltResource.setEnabled(true);
			requestResource.setEnabled(true);
			fastButton.setEnabled(true);
			slowButton.setEnabled(true);
			if(at != null) at.stop();
			at = null;
			return true;
		}
		else{ return false;}

	}

}