How to get rid of the titlebar in Android, the solution that all three kinds of methods on the net complain

The Beginner Android project is bound to meet the urge to remove titlebar.

Online search There are roughly three ways: 1. Realize that all the activity in the application is full screen

Join Android:theme= "@android: Style/theme.notitlebar.fullscreen" directly in manifest
2. Achieve a single activity Full-screen requestwindowfeature (window.feature_no_title);
GetWindow (). SetFlags (WindowManager.LayoutParams.TYPE_STATUS_BAR, WindowManager.LayoutParams.TYPE_STATUS_BAR); 3. Achieve single activity remove TITLE column requestwindowfeature (window.feature_no_title);

But try, not only not effective but also the error:

After repeated attempts and comparisons, it was found that the problem was not that these methods were wrong, but that the generated classes were integrated by the activity of the activity, as the following arrow activity was mainactivity extends actionbaractivity. Change the actionbaractivity back to the activity again and try to pass.