How to get GestureDetector working correctly
===

I have this code so far in my Activity:

    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();
	        Log.d("MainDisplayActivity", "Gesture class is running");
	        if (diffAbs > SWIPE_MAX_OFF_PATH)
	          return false;
	        
	        // Left swipe
	        if (diff > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
	           MainDisplayActivity.this.onLeftSwipe();

	        // Right swipe
	        } else if (-diff > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
	          MainDisplayActivity.this.onRightSwipe();
	          
	        }
	        
	      } catch (Exception e) {
	        Log.e("YourActivity", "Error on gestures");
	        
	      }
	      return false;
	    }
	   	
	  }//end of SwipeGestureDetector class
	  
	  //methods called by SwipeGestureDetector when the approrpiate swipes occured
	  private void onLeftSwipe() {
		    Toast.makeText(this, "Successfully have the swipe working for left", Toast.LENGTH_SHORT).show();
	  }

	  private void onRightSwipe() {
		  Toast.makeText(this, "Successfully have the swipe working for right", Toast.LENGTH_SHORT).show();
	  }

and I have this global: `private GestureDetector gestureDetector;`

and on `onCreate` I have this because its what I have seen people do:

    gestureDetector = new GestureDetector(this, new SwipeGestureDetector());
        ((LinearLayout)findViewById(R.id.parent_main_display)).setOnTouchListener(new View.OnTouchListener() {
			@Override
			public boolean onTouch(View v, MotionEvent event) {
				return gestureDetector.onTouchEvent(event);
			}
		});

Not really sure what I am doing wrong, but nothing is happening when I swipe. Any ideas?