Android – You need to use a Theme.AppCompat theme (or descendant) with this activity

You need to use a Theme.AppCompat theme (or descendant) with this activity is a common error message that appears when trying to run an Android application. This error occurs because the Android operating system requires the use of a specific theme for the application’s main activity. In this article, we’ll explore the cause of this error and the steps you can take to resolve it.

What causes the error?

The error message “You need to use a Theme.AppCompat theme (or descendant) with this activity” occurs because the Android operating system requires the use of a specific theme for the application’s main activity. The Theme.AppCompat theme is part of the Android Support Library and provides backward compatibility for older versions of Android. If you’re using a different theme, your application may not run correctly on older devices, or it may not display the correct styling on newer devices.

How to fix the error?

To resolve the error, you need to ensure that the application’s main activity is using a Theme.AppCompat theme (or descendant) as its parent theme.

Method 1: Fixing the current theme used in your project

Step #1: Open the AndroidManifest.xml file: 

GeekTip: This file is located in the “app/manifests” folder of your Android project.

Step #2: Locate the main activity for your application: You’ll see a section of the file that looks like this:

XML

<activity android:name=".GeeksforGeeksMainActivity">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

Step #3: Add the theme to the main activity: To add the theme to the main activity, you need to add the following line of code within the <activity> tag:

android:theme="@style/Theme.AppCompat"

Step #4: Restart the application, and you will find that the error has been fixed if it was being caused due to the AppCompat, otherwise if your application is still crashing you can continue with trying the next steps given in this article to fix it.

Method 2: Using a new theme altogether

Use a different Theme.AppCompat theme: Instead of using the default Theme.AppCompat theme, you can use one of its descendants, such as Theme.AppCompat.Light or Theme.AppCompat.Light.DarkActionBar. To do this, simply change the theme in the AndroidManifest.xml file as described in the previous method. 

Step #1: Change the theme in the themes.xml file:

XML

<resources xmlns:tools="http://schemas.android.com/tools">
    <!-- Base application theme. -->
    <style name="Theme.GeeksforGeeks" parent="Theme.MaterialComponents.DayNight.NoActionBar">
        <!-- Primary brand color. -->
        <item name="colorPrimary">@color/orange_500</item>
        <item name="colorPrimaryVariant">@color/orange_700</item>
        <item name="colorOnPrimary">@color/white</item>
        <!-- Secondary brand color. -->
        <item name="colorSecondary">@color/teal_200</item>
        <item name="colorSecondaryVariant">@color/teal_700</item>
        <item name="colorOnSecondary">@color/black</item>
        <!-- Status bar color. -->
        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
    </style>
</resources>

If none of the existing Theme.AppCompat themes meet your needs, you can create a custom Theme.AppCompat theme. To do this, create a new style resource in the “res/values” folder of your Android project and specify the parent theme as Theme.AppCompat. Then, you can define your custom styles and colors within this new style resource.

Method 3: Avoiding the Action Bar in your Android App

Step #1: You will need to change the action bar to no action bar in the theme file like below:

android:theme="@style/Theme.AppCompat.NoActionBar">

Alternatively

android:theme="@style/Theme.AppCompat" >

If you still want the action bar to be present in your application.

Method 4: Programmatically apply the theme to solve the issue

You can use this method if the above methods are not working, using this we will change the theme of your app with the java code.

Step #1: Creating a custom theme:

We will create a new theme, in this case, the name is ‘GeeksforGeeks’, you can change it accordingly:

XML

<style name="Theme.GeeksforGeeks" parent="Theme.MaterialComponents.DayNight.NoActionBar">
        <item name="colorPrimary">@color/green_400</item>
        <item name="colorPrimaryVariant">@color/green_200</item>
        <item name="colorOnPrimary">@color/white</item>
</style>

Step #2: Applying theme using java file:

We will now add the below line to apply the theme, which will fix the error:

Java

@Override
protected void onCreate(Bundle savedInstanceState)
{
      // Use this line to set the theme
      // Name of our theme is GeeksforGeeks
    setTheme(R.style.GeeksforGeeks);
    super.onCreate(savedInstanceState);
    setContentView(R.layout.geeks_for_geeks_main_activity);
}

By using these steps, you will be able to fix this error, one of them will resolve your issue, and get you back running!

Conclusion

This error is a common issue when developing Android applications. By ensuring that the main activity uses a Theme.AppCompat theme (or descendant) as its parent theme, you can resolve this error and ensure that your application runs correctly on all Android devices. Hope this article with these simple steps, will help you to resolve this error and get your application up and running smoothly.