Android Manually Managing Configuration Changes


Example

If your application doesn't need to update resources during a specific configuration change and you have a performance limitation that requires you to avoid the activity restart, then you can declare that your activity handles the configuration change itself, which prevents the system from restarting your activity.

However, this technique should be considered a last resort when you must avoid restarts due to a configuration change and is not recommended for most applications. To take this approach, we must add the android:configChanges node to the activity within the AndroidManifest.xml:

<activity android:name=".MyActivity"
          android:configChanges="orientation|screenSize|keyboardHidden"
          android:label="@string/app_name">

Now, when one of these configurations change, the activity does not restart but instead receives a call to onConfigurationChanged():

// Within the activity which receives these changes
// Checks the current device orientation, and toasts accordingly
@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);

    // Checks the orientation of the screen
    if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
        Toast.makeText(this, "landscape", Toast.LENGTH_SHORT).show();
    } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT){
        Toast.makeText(this, "portrait", Toast.LENGTH_SHORT).show();
    }
}

See the Handling the Change docs. For more about which configuration changes you can handle in your activity, see the android:configChanges documentation and the Configuration class.