Android Programming: The Big Nerd Ranch Guide, Third Edition

Handling Touch Events

One way to listen for touch events is to set a touch event listener using the following View method:

    public void setOnTouchListener(View.OnTouchListener l)

This method works the same way as setOnClickListener(View.OnClickListener). You provide an implementation of View.OnTouchListener, and your listener will be called every time a touch event happens.

However, because you are subclassing View, you can take a shortcut and override this View method instead:

    public boolean onTouchEvent(MotionEvent event)

This method receives an instance of MotionEvent, a class that describes the touch event, including its location and its action. The action describes the stage of the event:

Action constants ...