AppTheme.NoActionBar "AppTheme" in red and app won't run-CodePudding

I'm following this tutorial on Youtube on how to create a navigation menu bar https://youtu.be/fGcMLu1GJEc

And I have this in my theme.xml file

<style name="AppTheme.NoActionBar">
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
    </style>

but the AppTheme is in red and the application won't run I've checked many times and I just can't see where it could've gone wrong, the Youtube video is relatively old so perhaps it should be written in a different way with the newer version now?

CodePudding user response：

Have you specified the AppTheme in your theme.xml ? Make sure these 2 steps are completed

You have a style named "AppTheme" in your theme.xml

 <style name="AppTheme" parent="Theme.MaterialComponents.DayNight">
        <item name="colorPrimary">@color/purple_500</item>
        <item name="colorPrimaryVariant">@color/purple_700</item>
        <item name="colorOnPrimary">@color/white</item>
    </style>

AppTheme.NoActionBar will only work if you've already added an AppTheme

Explaination :- AppTheme.NoActionBar means, you're using AppTheme that you've already added in a new theme and on top of it you're adding one more attribute that this AppTheme will not have any Action Bar.

<style name="AppTheme.NoActionBar" parent="Theme.MaterialComponents.DayNight.NoActionBar">
        <item name="android:textColor">@color/black</item>
    </style>

CodePudding user response：

proper way to do this:

        <style name= "Theme.projectName" parent="Theme.AppCompat.NoActionBar"> 

         ...//set styles
         </style>

       eg:

     <style name="Theme.AppTheme" parent= "Theme.AppCompat.NoActionBar">

      Now where ever you want to apply different properties for an element

     <style name="name_of_style" parent="Theme.AppTheme">
      ...
     </style>

      eg:

     <style name="AppNoActionBar" parent="Theme.Apptheme"> 
         <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
     </style>

       <style name="toolbar_matrix" parent="Theme.AppTheme">

        ....
         ....
       </style>