Activity, AppCompatActivity, FragmentActivity, and

Question

I'm coming from iOS where it's easy and you simply use a UIViewController. However, in Android things seem much more complicated, with certain UIComponents for specific API Levels. I'm reading BigNerdRanch for Android (the book is roughly 2 years old) and they suggest I use Activity to host my FragmentActivities. However, I thought Activity was deprecated.

So for API Level 22 (with a minimum support for API Level 15 or 16), what exactly should I use both to host the components, and for the components themselves? Are there uses for all of these, or should I be using one or two almost exclusively?

Answer 1

2018: Use AppCompatActivity

At the time of this writing (check the link to confirm it is still true), the Android Documentation recommends using AppCompatActivity if you are using an App Bar.

This is the rational given:

Beginning with Android 3.0 (API level 11), all activities that use the default theme have an ActionBar as an app bar. However, app bar features have gradually been added to the native ActionBar over various Android releases. As a result, the native ActionBar behaves differently depending on what version of the Android system a device may be using. By contrast, the most recent features are added to the support library's version of Toolbar, and they are available on any device that can use the support library.

For this reason, you should use the support library's Toolbar class to implement your activities' app bars. Using the support library's toolbar helps ensure that your app will have consistent behavior across the widest range of devices. For example, the Toolbar widget provides a material design experience on devices running Android 2.1 (API level 7) or later, but the native action bar doesn't support material design unless the device is running Android 5.0 (API level 21) or later.

The general directions for adding a ToolBar are

1. Add the v7 appcompat support library
2. Make all your activities extend AppCompatActivity
3. In the Manifest declare that you want NoActionBar.
4. Add a ToolBar to each activity's xml layout.
5. Get the ToolBar in each activity's onCreate.

See the documentation directions for more details. They are quite clear and helpful.

Answer 2

Since the name is likely to change in future versions of Android (currently the latest is AppCompatActivity but it will probably change at some point), I believe a good thing to have is a class Activity that extends AppCompatActivity and then all your activities extend from that one. If tomorrow, they change the name to AppCompatActivity2 for instance you will have to change it just in one place.

Answer 3

Activity is the base class of all other activities, I don't think it will be deprecated. The relationship among them is:

Activity <- FragmentActivity <- AppCompatActivity <- ActionBarActivity

'<-' means inheritance here. The reference said ActionBarActivity is deprecated, use AppCompatActivity instead.

So basically, using AppCompatActivity is always the right choise. The differences between them:

• Activity is the basic one.
• Based on Activity, FragmentActivity provides the ability to use Fragment.
• Based on FragmentActivity, AppCompatActivity provides features to ActionBar.

Answer 4

There is a lot of confusion here, especially if you read outdated sources.

The basic one is Activity, which can show Fragments. You can use this combination if you're on Android version > 4.

However, there is also a support library which encompasses the other classes you mentioned: FragmentActivity, ActionBarActivity and AppCompat. Originally they were used to support fragments on Android versions < 4, but actually they're also used to backport functionality from newer versions of Android (material design for example).

The latest one is AppCompat, the other 2 are older. The strategy I use is to always use AppCompat, so that the app will be ready in case of backports from future versions of Android.

Answer 5

For a minimum API level of 15, you'd want to use AppCompatActivity. So for example, your MainActivity would look like this:

public class MainActivity extends AppCompatActivity {
    ....
    ....
}

To use the AppCompatActivity, make sure you have the Google Support Library downloaded (you can check this in your Tools -> Android -> SDK manager). Then just include the gradle dependency in your app's gradle.build file:

compile 'com.android.support:appcompat-v7:22:2.0'

You can use this AppCompat as your main Activity, which can then be used to launch Fragments or other Activities (this depends on what kind of app you're building).

The BigNerdRanch book is a good resource, but yeah, it's outdated. Read it for general information on how Android works, but don't expect the specific classes they use to be up to date.

Answer 6

AppCompatActivity extends FragmentActivity extends BaseFragmentActivityApi16 extends BaseFragmentActivityApi14 extends SupportActivity extends Activity

So Activity is faster than all & AppCompatActivity is the best of all.