Check the key event : Key Event « J2ME « Java Tutorial

1. Java Tutorial
2. J2ME
3. Key Event

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;
import javax.microedition.midlet.MIDlet;

public class KeyMIDlet extends MIDlet {
  public void startApp() {
    Displayable d = new KeyCanvas();

    d.addCommand(new Command("Exit", Command.EXIT, 0));
    d.setCommandListener(new CommandListener() {
      public void commandAction(Command c, Displayable s) {
        notifyDestroyed();
      }
    });

    Display.getDisplay(this).setCurrent(d);
  }

  public void pauseApp() {
  }

  public void destroyApp(boolean unconditional) {
  }
}

class KeyCanvas extends Canvas {
  private Font mFont= Font.getFont(Font.FACE_PROPORTIONAL, Font.STYLE_PLAIN, Font.SIZE_MEDIUM);

  private String mMessage = "[Press keys]";

  public void paint(Graphics g) {
    int w = getWidth();
    int h = getHeight();
    int x = w / 2;
    int y = h / 2;

    g.drawString(mMessage, x, y, Graphics.BASELINE | Graphics.HCENTER);
  }

  protected void keyPressed(int keyCode) {
    int gameAction = getGameAction(keyCode);
    switch (gameAction) {
    case UP:
      mMessage = "UP";
      break;
    case DOWN:
      mMessage = "DOWN";
      break;
    case LEFT:
      mMessage = "LEFT";
      break;
    case RIGHT:
      mMessage = "RIGHT";
      break;
    case FIRE:
      mMessage = "FIRE";
      break;
    case GAME_A:
      mMessage = "GAME_A";
      break;
    case GAME_B:
      mMessage = "GAME_B";
      break;
    case GAME_C:
      mMessage = "GAME_C";
      break;
    case GAME_D:
      mMessage = "GAME_D";
      break;
    default:
      mMessage = "";
      break;
    }
    repaint();
  }
}

31.19.Key Event
	31.19.1.	Canvas key events
	31.19.2.	Check the key event
	31.19.3.	Get key code
	31.19.4.	Game action