Android: How to detect double-tap?

You can use the GestureDetector. See the following code:

public class MyView extends View {

    GestureDetector gestureDetector;

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
                // creating new gesture detector
        gestureDetector = new GestureDetector(context, new GestureListener());
    }

    // skipping measure calculation and drawing

        // delegate the event to the gesture detector
    @Override
    public boolean onTouchEvent(MotionEvent e) {
        return gestureDetector.onTouchEvent(e);
    }


    private class GestureListener extends GestureDetector.SimpleOnGestureListener {

        @Override
        public boolean onDown(MotionEvent e) {
            return true;
        }
        // event when double tap occurs
        @Override
        public boolean onDoubleTap(MotionEvent e) {
            float x = e.getX();
            float y = e.getY();

            Log.d("Double Tap", "Tapped at: (" + x + "," + y + ")");

            return true;
        }
    }
}

You can override other methods of the listener to get single taps, flinges and so on.

As a lightweight alternative to GestureDetector you can use this class

public abstract class DoubleClickListener implements OnClickListener {

    private static final long DOUBLE_CLICK_TIME_DELTA = 300;//milliseconds

    long lastClickTime = 0;

    @Override
    public void onClick(View v) {
        long clickTime = System.currentTimeMillis();
        if (clickTime - lastClickTime < DOUBLE_CLICK_TIME_DELTA){
            onDoubleClick(v);
        } else {
            onSingleClick(v);
        }
        lastClickTime = clickTime;
    }

    public abstract void onSingleClick(View v);
    public abstract void onDoubleClick(View v);
}

Example:

    view.setOnClickListener(new DoubleClickListener() {

        @Override
        public void onSingleClick(View v) {

        }

        @Override
        public void onDoubleClick(View v) {

        }
    });

Why aren’t you using a Long Press? Or are you using that already for something else? The advantages of a Long Press over a Double Touch:

  • Long Press is a recommeded interaction in the UI Guidelines, Double Touch is not.
  • It’s what users expect; a user might not find a Double Touch action as they won’t go looking for it
  • It’s already handled in the API.
  • Implementing a Double Touch will affect handling of Single Touches, because you’ll have to wait to see if every Single Touch turns into a Double Touch before you can process it.

Leave a Comment