How to catch double tap events in Android using OnTouchListener

That's much easyer:

//variable for storing the time of first click
long startTime;
//constant for defining the time duration between the click that can be considered as double-tap
static final int MAX_DURATION = 200;

    if (event.getAction() == MotionEvent.ACTION_UP) {

        startTime = System.currentTimeMillis();             
    }
    else if (event.getAction() == MotionEvent.ACTION_DOWN) {

        if(System.currentTimeMillis() - startTime <= MAX_DURATION)
        {
            //DOUBLE TAP
        }       
    }

In your class definition:

public class main_activity extends Activity
{
    //variable for counting two successive up-down events
   int clickCount = 0;
    //variable for storing the time of first click
   long startTime;
    //variable for calculating the total time
   long duration;
    //constant for defining the time duration between the click that can be considered as double-tap
   static final int MAX_DURATION = 500;
}

Then in your class body:

OnTouchListener MyOnTouchListener = new OnTouchListener()
{
    @Override
    public boolean onTouch (View v, MotionEvent event)
    {
        switch(event.getAction() & MotionEvent.ACTION_MASK)
        {
        case MotionEvent.ACTION_DOWN:
            startTime = System.currentTimeMillis();
            clickCount++;
            break;
        case MotionEvent.ACTION_UP:
            long time = System.currentTimeMillis() - startTime;
            duration=  duration + time;
            if(clickCount == 2)
            {
                if(duration<= MAX_DURATION)
                {
                    Toast.makeText(captureActivity.this, "double tap",Toast.LENGTH_LONG).show();
                }
                clickCount = 0;
                duration = 0;
                break;             
            }
        }
    return true;    
    }
}

This was adapted from an answer in: DoubleTap in android by https://stackoverflow.com/users/1395802/karn

With the helper class SimpleGestureListener that implements the GestureListener and OnDoubleTapListener you dont need much to do.

yourView.setOnTouchListener(new OnTouchListener() {
private GestureDetector gestureDetector = new GestureDetector(Test.this, new GestureDetector.SimpleOnGestureListener() {
    @Override
    public boolean onDoubleTap(MotionEvent e) {
        Log.d("TEST", "onDoubleTap");
        return super.onDoubleTap(e);
    }
    ... // implement here other callback methods like onFling, onScroll as necessary
});

@Override
public boolean onTouch(View v, MotionEvent event) {
    Log.d("TEST", "Raw event: " + event.getAction() + ", (" + event.getRawX() + ", " + event.getRawY() + ")");
    gestureDetector.onTouchEvent(event);
    return true;
}});