Bouncing Ball

PROBLEM STATEMENT
Create an application to demonstrate Bouncing Ball, create a menu for the above with 2 options: start and stop to pause and resume the bouncing ball.

CODE

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;


public class BouncingBallMidlet extends MIDlet {
//Declaring BouncingBallCanvas object

private BouncingBallCanvas bbc;

//Declaring Display object

private Display display;
public BouncingBallMidlet()
{

//Initailizing BouncingBallCanvas object.

bbc = new BouncingBallCanvas(this);
}

public void startApp()
{

// Indicating the object to be Displayed

display = Display.getDisplay(this);
display.setCurrent(bbc);
}
public void pauseApp()
{
}

public void destroyApp(boolean unconditional)
{
}

public void exitButton()
{

// Indicating the object to be Displayed
destroyApp(false);
notifyDestroyed();
}




import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import java.util.Random;

public class BouncingBallCanvas extends Canvas implements CommandListener, Runnable
{
BouncingBallMidlet bbm;
Display display;
Command quitCommand;
Command startCommand;
Command pauseCommand;

//Declaring Random’s object

Random rand;

//Declaring Thread’s object

Thread t;

int stopFlag;
int x, y;
int dx, dy;
int r, gr, b;

public BouncingBallCanvas()
{
}

public BouncingBallCanvas(BouncingBallMidlet bbm)
{
this.bbm = bbm;
// Indicating the object to be Displayed

display = Display.getDisplay(bbm);

//Initailizing Random’s object.

rand = new Random();

//Initailizing Command buttons

quitCommand = new Command("Quit", Command.EXIT, 0);
startCommand = new Command("Start", Command.SCREEN, 0);
pauseCommand = new Command("Pause", Command.STOP, 0);

//Adding Command to current form

addCommand(quitCommand);
addCommand(pauseCommand);

// Adding Command Listner

setCommandListener(this);

//Initailizing Thread’s object.

t = new Thread(this);
stopFlag = 0;
dx = 10;
dy = 10;
x = 8;
y = 12;

//Generating the Random number in the range of 0 to 255 and assigning it to the variable.

r = gr = b = Math.abs(rand.nextInt()%255);

//Starting the Thread t

t.start();
}

protected void paint(Graphics g)
{
g.setColor(255, 255, 255);
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(r, gr, b);
g.fillArc(x , y, 20, 20, 0, 360);

if (x > getWidth()-23 || x < 8)
{
dx = -dx;
r = Math.abs(rand.nextInt()%255);
gr = Math.abs(rand.nextInt()%255);
b = Math.abs(rand.nextInt()%255);
}
if (y > getHeight()-21 || y < 12)
{
dy = -dy;
r = Math.abs(rand.nextInt()%255);
gr = Math.abs(rand.nextInt()%255);
b = Math.abs(rand.nextInt()%255);
}
x += dx;
y += dy;
}

//Condition to get and check the user input

Command getCurrentCommand()
{
switch(stopFlag)
{
case 0:
return pauseCommand;
case 1:

return startCommand;
default:
return startCommand;
}
}

public void commandAction(Command command, Displayabl displayable)
{
addCommand(getCurrentCommand());

if(command == quitCommand)
{
bbm.exitButton();
}
else if(command == startCommand)
{
t = new Thread(this);
stopFlag = 0;
this.removeCommand(startCommand);
addCommand(pauseCommand);
t.start();
}
else if(command == pauseCommand)
{
stopFlag = 1;
t = null;
this.removeCommand(pauseCommand);
addCommand(startCommand);
}
}

public void run()
{
for( ; ; )
{
try
{
repaint();

//Thread is sleep for 170 mill second

Thread.sleep(170);
if(stopFlag == 1)
break;
}
catch(InterruptedException ie)
{
}
}
}
}