Typically events do responds to user interactions. Android platform supports multiple ways to handle the events on View’s. When user clicks on an Android View, some method is getting called by the android framework and then passed the control to the application listeners. For example, when a user clicks on a view such as a Button, the onTouchEvent() method is called on that Button object. In order to make our application to responds to the event we must extend the class and override the method. But extending every View object in order to handle such an event would not be practical. Each View classes in Android provide collection of nested interfaces called listeners with callbacks that you can much more easily define in order to handle event.