How to create an inclusive aar file in Android?

Why do some android programmers uses View class to create buttons?

• I'm currently learning Android programming and the way I used to create command buttons in the activity class (not xml) is to "import android.widget.Button;" and then to create the Button instance such as " Button exit = (Button) findViewById(R.id.exitButton); " But I have came across some source code file that contains a View instance that is being used as a button. The rest of the code seems to be similar but the only difference is he is using View class instead of Button class. Can someone please tell me the difference between these two methods? Thanks in advance!

• Answer:

  There is not much difference. Think of widget as custom and ready-to-use View. In developer site it says: "The widget package contains (mostly visual) UI elements to use on your Application screen. You can design your own" http://developer.android.com/reference/android/widget/package-summary.html And if you design your own widget you have to extend View as well. So you're making use of View whether you're using View (directly) or widget (indirectly). Take a look at the android.widget.Button hierarchy at the top of: http://developer.android.com/reference/android/widget/Button.html