How to change android button text color globally in theme

With the new Theme.MaterialComponents theme you can define the materialButtonStyle attribute in your app theme, to customize globally the style of all buttons in your app.

  <!-- Base application theme. -->
  <style name="AppTheme" parent="Theme.MaterialComponents.Light">
       <!-- .... --> 
       <item name="materialButtonStyle">@style/Widget.App.Button</item>
  </style>

With

<style name="Widget.App.Button" parent="Widget.Material3.Button">
    <!-- button style customization example -->
    <item name="materialThemeOverlay">@style/ThemeOverlay.App.Button</item>
    <item name="android:textAppearance">@style/TextAppearance.App.Button</item>
    <item name="shapeAppearance">@style/ShapeAppearance.App.SmallComponent</item>
</style>

Use Widget.MaterialComponents.Button as parent if you are using Material2 theme.

If you would like to override only some attributes like colors from the default style use the materialThemeOverlay attribute.

Something like:

  <style name="Widget.App.Button" parent="Widget.Material3.Button">
    <item name="materialThemeOverlay">@style/ThemeOverlay.App.Button</item>
  </style>

  <style name="ThemeOverlay.App.Button">
    <!-- For filled buttons, your theme's colorPrimary provides the default background color of the component, and -->
    <!--the text color is colorOnPrimary -->
    <item name="colorPrimary">@color/my_color</item>
    <item name="colorOnPrimary">@color/my_color2</item>
    
  </style>

If you just need to change the text colour of buttons. You can modify the textAppearanceButton style attribute of your main theme.

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="colorButtonNormal">@color/buttonColor</item>
    <item name="android:textAppearanceButton">@style/TextAppearance.AppCompat.Button.Custom</item>
</style>

And declare your new textAppearance style as follows

<style name="TextAppearance.AppCompat.Button.Custom">
    <item name="android:textColor">@color/mycustomcolor</item>
</style>

 <style name="AppTheme.Base" parent="Theme.AppCompat.Light.DarkActionBar">
   <item name="android:textColor">#yourcolor</item>
    <item name="android:buttonStyle">@style/ButtonColor</item>
    <item name="colorButtonNormal">@color/buttonColor</item>
</style>



<style name="ButtonColor" parent="@android:style/Widget.Button">
   <item name="android:textColor">@color/yourcolor</item>
</style> 

android:textColor This should help you change the text color globally.