Java Programing laungage

/*
 * save as a addCanvas.java
 */
package r4r.Mobile.Basic;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
/**
 * @author R4R
 */
public class addCanvas extends MIDlet {
 /* -- private field -- */
 private Canvas canvas;
 private Display display;
 private Command exit;
 public addCanvas() {
 display = Display.getDisplay(this);
 canvas = new userCanvas(); //invoke userCanvas class
 exit = new Command("EXIT", Command.EXIT, 1);
 canvas.addCommand(exit); // add command button into canvas
 }
				
 public void startApp() {
 canvas.setCommandListener(new CommandListener() {
 public void commandAction(Command c, Displayable d) {
 if (c == exit) {
 destroyApp(true);
 notifyDestroyed();
 }
 }
 });
 display.setCurrent(canvas);
 }
 public void pauseApp() {
 }
 public void destroyApp(boolean unconditional) {
 }
}
class userCanvas extends Canvas {
 protected void paint(Graphics g) {
 g.fillRect(0, 0, getWidth(), getHeight());
 // set up back ground color of canvas
 g.setColor(255, 255, 255);
 // draw and fill the rectangle with a specific color
 g.fillRect(40, 50, 70, 70);
 g.setColor(200, 100, 0);
 }
}