Handle touch input by converting screen → virtual coordinates before game logic. | Problem | Cause | Fix | |--------|-------|-----| | Touch not detected | No pointer events supported | Add vendor API fallback or emulate via keypad | | Slow drag | Full repaint on every move | Only repaint affected area or use repaint(x,y,w,h) | | Sticky touch | No pointerReleased called | Add timeout reset after 500ms | | Accidental taps | Too sensitive | Require min drag distance of 5px before action | | Overlapping UI | Fingers cover screen | Place UI at bottom/edges, use haptic feedback (if supported via DeviceControl – rare) | 8. Example: Simple Touch Arcade Shooter import javax.microedition.lcdui.*; import javax.microedition.midlet.*; public class TouchShooter extends MIDlet implements CommandListener { private Display display; private GameCanvas canvas; private Command exitCommand;

Most vendors ignored these until later JTWI/Java Verified phones. Use vendor-specific APIs. Nokia Touch API (S60 5th Ed / S40) // Need: com.nokia.mid.ui.TouchEvent import com.nokia.mid.ui.TouchEvent; import com.nokia.mid.ui.TouchDevice; // In FullCanvas subclass public void pointerPressed(int x, int y) // still works, but better:

// Or via TouchEvent listener: TouchDevice.addListener(touchListener); They support standard pointerPressed reliably. No extra JAR needed. Defensive detection pattern: public boolean isTouchSupported() { try Class.forName("com.nokia.mid.ui.TouchEvent"); return true; catch (ClassNotFoundException e) {} // Also test if pointerPressed works: return getClass().getMethod("pointerPressed", int.class, int.class) != null; // rough } Better: check touch capability via Canvas.hasPointerEvents() (midp 2.0) – but that returns false if not supported.

(e.g., tower defense, puzzle) Store last tap point and move character toward it.

protected void paint(Graphics g) g.setColor(0); g.fillRect(0, 0, getWidth(), getHeight()); g.setColor(0x00FF00); g.fillRect(playerX - 10, playerY - 10, 20, 20); drawBullets(g); // ... bullet management methods }