Android error - Must specify preferenceTheme in Theme

Question

I created a layout (preferences.xml) in the res/xml directory based on Preferencescreen.

I implemented a class derived from Preferencesfragmentcompat

public class PrefsFragment extends PreferenceFragmentCompat  
{
  @Override   
  public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
    setPreferencesFromResource(R.xml.preferences, rootKey);    
  }
}

I implemented Activity of preferences

public class PrefsActivity extends AppCompatActivity
{

  @Override
  protected void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.prefs_activity);

    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.fragContent, new PrefsFragment());
    transaction.commit();
  }

} 

When I run Activity the following error is displayed:

java.lang.Runtimeexception: Unable to start Activity Componentinfo{Prefsactivity}: java.lang.Illegalstateexception: Must specify preferenceTheme in Theme

How do I specify the preferenceTheme?

Answer 1

In the archive res/values/styles.xml add

<item name="preferenceTheme">@style/PreferenceThemeOverlay</item>

If you haven’t changed anything in the file generated by Android Studio will look like this:

<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>

    <item name="preferenceTheme">@style/PreferenceThemeOverlay</item>
</style>

If you’re using the v7 Preference Support Library I advise you to replace it with v14 Preference Support Library because in v7 there are "problems" with the preferenceTheme.