How to fix: “You need to use a Theme.AppCompat theme (or descendant) with this activity”

Question

I am having trouble running my Android app in a fullscreen mode per instructions of a video. When it tries to run, the app crashes with the error.

\"You need t

Answer 1

Your application has an AppCompat theme

But, you overwrote the Activity (which extends AppCompatActivity) with a theme that isn't descendant of an AppCompat theme

You could define your own fullscreen theme like so (notice AppCompat in the parent=)

Then set that on the Activity.

Note: There might be an AppCompat theme that's already full screen, but don't know immediately