android - What's the enhancement of AppCompatActivity over ActionBarActivity?

Question

android.support.v7.app.AppCompatActivity was added into the latest v7 support library as a new feature yesterday.

It is said that ActionBarActivity has been deprecated in favor of the new AppCompatActivity and that AppCompatActivity is base class for activities that use the support library action bar features. So, what are new features of AppCompatActivity over ActionBarActivity? What enhancements do AppCompatActivity have over ActionBarActivity? And what are advantages of AppCompatActivity? Could somebody supply a few samples?

PS: what surprised me most is that AppCompatActivity which is extended from android.support.v4.app.FragmentActivity is the direct parent class of ActionBarActivity! I mean actually now that ActionBarActivity can do anything that AppCompatActivity can do, why did Android pushed out the latter?

Meanwhile, I saw a blog post that states: "It's not a rename from ActionBarActivity to AppCompatActivity, the internal logic of AppCompat is available via AppCompatDelegate", so what's the "internal logic" of AppCompat? What can AppCompatDelegate do? Could somebody post some codes about this?

Answer 1

As Chris wrote, new deprecated version of ActionBarActivity (the one extending AppCompatActivity class) is a safe to use backward compatibility class. Its deprecation is just a hint for you asking to use new AppCompatActivity directly instead. AppCompatActivity is a new, more generic implementation which uses AppCompatDelegate class internally.

If you start a new development, then you should rather use new AppCompatActivity class right away. If you have a chance to update your app, then replace deprecated ActionBarActivity by the new activity as well. Otherwise you can stay with deprecated activity and there will be no difference in behavior at all.

Regarding AppCompatDelegate, it allows you to have new tinted widgets in an activity, which is neither AppCompatActivity nor ActionBarActivity.

For instance, you inherit an activity from an external library, which, in turn, does not inherit from AppCompatActivity but you want this activity to have tinted materials widgets (views). To make it happen you need to create an instance of AppCompatDelegate inside your activity, override methods of that activity like addContentView(), setContentView() etc. (see AppCompatDelegate javadoc for the full list of methods), and inside of those overridden methods forward the calls to the inner AppCompatDelegate instance. AppCompatDelegate will do the rest and your "old-fashion" activity will be "materialized".