How to catch double tap events in Android using OnTouchListener

Question

I am trying to catch double-tap events using OnTouchListener. I figure I would set a long for motionEvent.ACTION_DOWN, and a different long for a second motionEvent.ACTION_D

Answer 1

Here is my solution.

It was important for me to have a fast and clear separation of 'single tap' and 'double tap'. I tried GestureDetector first but had very bad results. Maybe a result of my nested use of scrollviews - who knows...

I focus on MotionEvent.ACTION_UP and the ID of the tapped element. To keep the first tap alive I use a Handler sending a delayed message (350ms) so the user has some time to place its second tap on the ImageView. If the user placed a second tap on an element with the identical id I take this as double tap, remove the delayed message and rund my custom code for 'double tap'. If the user placed a tap on an element with a different ID I take this as new tap and create another Handler for it.

Class global variables

private int tappedItemId = -1;
Handler myTapHandler;
final Context ctx = this;

Code example

ImageView iv = new ImageView(getApplicationContext());
//[...]
iv.setId(i*1000+n);
iv.setOnTouchListener(new View.OnTouchListener() {

@Override
public boolean onTouch(View v, MotionEvent event) {

   switch (event.getAction()) {

      case MotionEvent.ACTION_UP: {

         //active 'tap handler' for current id?
         if(myTapHandler != null && myTapHandler.hasMessages(v.getId())) {

            // clean up (to avoid single tap msg to be send and handled)
            myTapHandler.removeMessages(tappedItemId);
            tappedItemId = -1;

            //run 'double tap' custom code
            Toast.makeText(ScrollView.this, "double tap on "+v.getId(), Toast.LENGTH_SHORT).show();

            return true;
         } else {
            tappedItemId = v.getId();
            myTapHandler = new Handler(){
               public void handleMessage(Message msg){
                  Toast.makeText(ctx, "single tap on "+ tappedItemId + " msg 'what': " + msg.what, Toast.LENGTH_SHORT).show();
               }
            };

            Message msg = Message.obtain();
            msg.what = tappedItemId;
            msg.obj = new Runnable() {
               public void run() {
                  //clean up
                  tappedItemId = -1;
               }
            };
            myTouchHandler.sendMessageDelayed(msg, 350); //350ms delay (= time to tap twice on the same element)
         }
         break;
      }
   }

   return true;
 }
});