26.6 The Event Listener and Callback Method
For the purposes of this example, an onClickListener needs to be registered for the myButton view. This is achieved by making a call to the setOnClickListener() method of the button view, passing through a new onClickListener object as an argument and implementing the onClick() callback method. Since this is a task that only needs to be performed when the activity is created, a good location is the onCreate() method of the MainActivity class.
If the MainActivity.java file is already open within an editor session, select it by clicking on the tab in the editor panel. Alternatively locate it within the Project tool window by navigating to (app -> java -> com.ebookfrenzy.eventexample -> MainActivity) and double-click on it to load it into the code editor. Once loaded, locate the template onCreate() method and modify it to obtain a reference to the button view, register the event listener and implement the onClick() callback method...