When developing applications in Android Studio 4.2, you might encounter an issue where the background color of Button controls cannot be modified, remaining stuck with a default blue-purple appearance regardless of your styling attempts.

Consider the following button configuration where background colors are explicitly defined:

<Button
    android:id="@+id/actionButton"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:text="Login"
    android:background="#3498db"/>
    
<Button
    android:id="@+id/secondaryButton"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:text="Sign Up"
    android:background="@drawable/custom_button_background"
    android:layout_marginTop="10dp"/>

Despite these specifications, the buttons may continue to display the default color scheme on both emulators and physical devices.

Solution Approach

The root cause of this issue typically lies in the theme definitions. The default styling behavior originates from the theme files located in res/values/themes.xml and for dark mode in res/values-night/themes.xml.

To resolve this, modify the theme in your themes.xml file:

Original theme definition:

<style name="AppTheme" parent="Theme.MaterialComponents.DayNight.DarkActionBar">

Modified theme definition:

<style name="AppTheme" parent="Theme.MaterialComponents.DayNight.DarkActionBar.Bridge">

Simply adding the .Bridge suffix to the parent theme often resolves the background color issue.

Alternative Solutions

If the .Bridge approach doesn't work, consider these alternatives:

1. Add the attribute app:backgroundTint="@null" to your button elements
2. Invalidate caches and restart Android Studio through File → Invalidate Caches / Restart
3. Consider using an earlier version of Android Studio if this is a version-specific issue
4. Review other theme properties in your themes.xml file for conflicting styles

Handling Uppercase Button Text

Another common issue in Android Studio is that button text automatically converts to uppercase, even when the orignial text contains lowercase letters.

The solution is straightforward - add the following attribute to your Button elements:

android:textAllCaps="false"

This property prevents the automatic capitalization of buttton text, allowing it to display in its original case as specified in you're layout or string resources.