OnTouch method of OnTouchListener subclass being called many times in Android

Question

I created a simple [View.OnTouchListener][1] implementation in my simple Android app.

My goal right now is to make it detect downward swiping. For example, if I swipe downward, I'd like it to detect that I've done so.

It does this succesfully, however, for each swipe downward, it also gets called a whole bunch of other times. I can see this because of the default behaviour in the onTouch methods switch statement:

This is MySwipeListener :

public class MySwipeListener implements View.OnTouchListener{
    private Activity activity;

    public MySwipeListener(Activity activity){
        this.activity = activity;
    }

    @Override
    public boolean onTouch(View view, MotionEvent motionEvent) {
        switch (motionEvent.getAction()){
            case MotionEvent.ACTION_DOWN: {
                Log.i("MotionEvent", "Action Down!");
                Toast.makeText(activity, "Motion Down", Toast.LENGTH_LONG);
                return true;
            }
            default: {
                Log.i("MotionEvent", "Other Action!");
                Toast.makeText(activity, "Other Action", Toast.LENGTH_LONG);
                return true;
            }
        }
    }
}

And this is how I'm using it in my MainActivity :

    Button topUp = (Button) findViewById(R.id.a);
    topUp.setOnTouchListener(new MySwipeListener(this));

When I physically swipe on my Android screen, I get results like:

09-16 16:39:48.276  26748-26748/mobi.corp.proj I/MotionEvent﹕ Action Down!
09-16 16:39:48.316  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.326  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.346  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.361  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.376  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.396  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.411  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.426  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.446  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.461  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.476  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.496  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.511  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.526  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.546  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.561  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.576  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.596  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.611  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.626  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.631  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.886  26748-26748/mobi.corp.proj I/MotionEvent﹕ Action Down!
09-16 16:39:48.911  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.926  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.946  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.961  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.976  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:48.996  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.011  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.026  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.046  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.061  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.076  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.096  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.111  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.126  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.146  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.161  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.176  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.196  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.201  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!
09-16 16:39:49.206  26748-26748/mobi.corp.proj I/MotionEvent﹕ Other Action!

when I'm just expecting a few

I/MotionEvent﹕ Action Down!

Answer 1

The log in the default is being printed because when you swipe on the screen ACTION_MOVE and probably ACTION_UP are called.

If you want to detect a downward swipe you need to get the y co-ordinate on ACTION_DOWN and compare it to the y co-ordinate you get in ACTION_UP .

If the y in ACTION_UP is greater than ACTION_UP then there is a downward swipe.

Answer 2

MotionEvent.ACTION_MOVE is called every time you move your finger an it is an continuous task. this will be called every pixel it moves. so you may want to exclude MotionEvent.ACTION_MOVE from this class to decrease the noise

Answer 3

You can try a method as seen in this tutorial to handle swipes.

Ex:

// Private class for gestures   
    private class SwipeGestureDetector 
          extends SimpleOnGestureListener {
    // Swipe properties, you can change it to make the swipe 
    // longer or shorter and speed
    private static final int SWIPE_MIN_DISTANCE = 120;
    private static final int SWIPE_MAX_OFF_PATH = 200;
    private static final int SWIPE_THRESHOLD_VELOCITY = 200;

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2,
                         float velocityX, float velocityY) {
      try {
        float diffAbs = Math.abs(e1.getY() - e2.getY());
        float diff = e1.getX() - e2.getX();

        if (diffAbs > SWIPE_MAX_OFF_PATH)
          return false;

        // Left swipe
        if (diff > SWIPE_MIN_DISTANCE
        && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
           YourActivity.this.onLeftSwipe();

        // Right swipe
        } else if (-diff > SWIPE_MIN_DISTANCE
        && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
          YourActivity.this.onRightSwipe();
        }
      } catch (Exception e) {
        Log.e("YourActivity", "Error on gestures");
      }
      return false;
    }
 }

private void onLeftSwipe() {
    // Do something
  }

private void onRightSwipe() {
    // Do something
  }