Dapet tugas buat bikin segitiga gerak pake java j2me, ane dah coba utak atik tetep aja bingung error nya dimana, waktu di build n di run sih bisa, tapi waktu masuk ke display segitiga yang gerak gak terjadi apa2, tapi di wireless tool kit malah keluar pesan error..

neh script javanya,

import javax.microedition.lcdui.*;

import javax.microedition.lcdui.game.*;

import javax.microedition.midlet.*;

import java.io.*;



public class GerakSegitiga extends MIDlet implements CommandListener{

 private Display display;

 private Form form;

 private Form form2;

 private TextBox textbox;

 private TextField name;

 private TextField pass;

 private Command exit;

 private Command login;

 private Command launch;

 private Command launch2;

 private Command Logout;

 private Command back;

 private Command back2;

 private List list;

 private Alert alert;

 public MainCanvas canvas;

 

 public GerakSegitiga(){

 try{

 MainCanvas canvas = new MainCanvas(this);

 display=Display.getDisplay(this);

 login=new Command("Login",Command.OK,1);

 exit=new Command("Exit",Command.EXIT,1);

 launch=new Command("Launch",Command.OK,1);

 launch2=new Command("Launch",Command.OK,1);

 back=new Command("Back",Command.BACK,1);

 Logout=new Command("Logout",Command.BACK,1);

 list = new List("Pilih bentuk", List.IMPLICIT);

 

 name = new TextField("Name:", "", 30, TextField.ANY);

 pass = new TextField("Password:", "", 10, TextField.PASSWORD);



 form=new Form("Login");

 form.append(name);

 form.append(pass);

 form.addCommand(exit);

 form.addCommand(login);

 form.setCommandListener(this);

 //----------------------------------------------------------//

 form2=new Form("Profil");

 form2.append("Nama : Jack Wilshere");

 form2.append("TTL : English");

 form2.append("Pekerjaan : Football Player");

 Image gbr=Image.createImage("/arsenal.png");

 form2.append(gbr);

 form2.addCommand(Logout);

 form2.addCommand(launch);

 form2.setCommandListener(this);

 //----------------------------------------------------------// 

 list.append("Segitiga", null);

 list.append("Bujur Sangkar", null);

 list.append("Jajaran Genjang", null);

 list.append("Trapesium", null);

 list.append("Layang-layang", null);

 list.append("Tidak Teratur", null);

 list.addCommand(back);

 list.addCommand(launch2);

 list.setCommandListener(this);

 //----------------------------------------------------------//

 

 }catch(IOException e){}

 }

 

 public void cekUser(String name, String pass) {

 if (name.equals("") && pass.equals("")) {

 display.setCurrent(form2);

 }

 else{

 Alert alert = new Alert("Peringatan","Kombinasi Name & Password tidak sesuai!",null, AlertType.INFO);

 display.setCurrent(alert);

 }

 } 

 

 public void startApp(){

 display.setCurrent(form);

 }

 public void pauseApp(){

 }

 public void destroyApp(boolean unconditional){

 }

 public void commandAction(Command command, Displayable displayable){

 if(command==login){

 cekUser(name.getString(), pass.getString());

 }

 else if(command==back){

 display.setCurrent(form2);

 }

 else if(command==Logout){

 display.setCurrent(form);

 }

 else if(command==launch){

 display.setCurrent(list);

 }

 else if (command == launch2 || command == List.SELECT_COMMAND) {

 int index = list.getSelectedIndex();

 if (index==0){

 back2 = new Command("Back", Command.BACK, 0);

 canvas.mulai();

 canvas.addCommand(back2);

 canvas.setCommandListener(new CommandListener(){

 public void commandAction(Command c, Displayable s) {

 notifyDestroyed();

 }

 });

 display.setCurrent(canvas);

 }

 else{

 Alert alert = new Alert("Bentuk","Pilihanmu " + list.getString(index) + ".",null, AlertType.INFO);

 display.setCurrent(alert, list);

 }

 }

 else if(command==exit){

 notifyDestroyed();

 }



 }

}

 

 

class MainCanvas extends GameCanvas implements Runnable {

 public MIDlet mainMidlet;

 public Graphics g;

 public static int SLEEP_TIME = 1000/30;

 public int ballX;

 public int ballY;

 public int speed_ballX;

 public int speed_ballY;



 public static int NUMBER_OF_MENU=4;



 protected MainCanvas(MIDlet midlet) {

 super(false);

 mainMidlet = midlet;

 this.setFullScreenMode(true);

 }



 public void mulai(){

 Thread runner = new Thread(this);

 runner.start();

 }



 public void run() {

 g = getGraphics();

 

 ballX = 60;

 speed_ballX = 3;

 while(true){

 g.setColor(0x000000);

 g.fillRect(0, 0, getWidth(), getHeight());

 drawCircle(ballX, ballY, 10, 0xffffff);

 flushGraphics();

 try {

 Thread.sleep(SLEEP_TIME);

 } catch (InterruptedException e) {

 e.printStackTrace();

 }

 ballX+=speed_ballX;

 if(ballX>getWidth()){

 speed_ballX*=-1;

 }else if(ballX<0){

 speed_ballX*=-1;

 }

 }

 }



 public void drawCircle(int x, int y, int diameter, int color){

 g.setColor(color);

 g.fillTriangle(x-diameter/2, 10, diameter, diameter, 10, getHeight()-10);

 }

}

mohon petunjuknya bagi yang ikhlas memberikan petunjuknya ane doain amal dan ibadahnnya diterima oleh yang maha kuasa..