Android Studio预览标题

Question

Recently I opened android studio to find that the App preview was not working at all. After coming on here it was advised to add base in front of the path name inside of the android manifest style tag like so:

<style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar">

originally it was (As you can see without the Base tag):

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">

My problem now is that it works but no matter what I do when I first start an app I HAVE to add base to the beginning of the style name mentioned above and I also cannot see the ACTUAL theme I am working on in the app preview section. I have tried changing the Theme to the Theme Thats in my style tag which is DarkActionBAr but all it does is then gives me the following error:

The following classes could not be instantiated: - android.support.v7.widget.ActionBarContainer (Open Class, Show Exception, Clear Cache) - android.support.v7.widget.ActionBarContextView (Open Class, Show Exception, Clear Cache) - android.support.v7.app.WindowDecorActionBar (Open Class, Show Exception, Clear Cache) Tip: Use View.isInEditMode() in your custom views to skip code or show sample data when shown in the IDE. If this is an unexpected error you can also try to build the project, then manually refresh the layout. Exception Details java.lang.ClassNotFoundException: android.view.View$OnUnhandledKeyEventListener Copy stack to clipboard

and

Failed to load AppCompat ActionBar with unknown error.

As always any help would be greatly appreciated. Thank You

Answer 1

Okay So after 2 hours of trying everything from deleting everything to searching everywhere I have come up with the answer.

My problem was with the compileSdkVersion. I had it set to 28. After checking another app that I had done a few days ago that was still working fine I went in and checked all the settings and compared them.

Afterward I rolled the other app back to 27 by changing the following inside of build.gradle:

from:

compileSdkVersion 28

To:

compileSdkVersion 27

from:

implementation 'com.android.support:appcompat-v7:28.0.0-beta01'

to:

implementation 'com.android.support:appcompat-v7:27.1.1'

Hopefully this will help others if you run into this problem.