For android's getActionBar (), null is returned. Or related questions

1) set <uses-sdk android: minSdkVersion = "4" android: targetSdkVersion = "11"/> to indicate that the application can be deployed on or before android3.0. That is to say, when the device SdkVersion = 11, the application starts the Action Bar.
But how can an application use the Action Bar API to access the ActionBar class. For example, add a tab and change the Action Bar style,

We need to set minSdkVersion to 11. Otherwise, your actions won't even happen,

There are also some funny ones:

GetWindow (). requestFeature (Window. FEATURE_ACTION_BAR );

You can use this sentence to get the ActionBar, but the ActionBar position is black.

Or in android 8.0

GetWindow (). requestFeature (8); all have the same effect, so... I want to use SDK11 or lower mobile phones

Do not use ActionBar, or there are a lot of bugs !!