public class SkinWizardApplication extends Application implements SkinManager.SkinProvider {
    @Override
    public void onCreate() {
        super.onCreate();
        SkinManager.getInstance().init(this);
    }

    @Override
    public int[] provideSkins() {
        return new int[]{R.style.Default, R.style.BlackNight};
    }
}

xmlns:van="http://schemas.android.com/van"

<TextView
 xmlns:van="http://schemas.android.com/van"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/colorAccent"
    android:text="MainActivity"
    android:textColor="@color/colorPrimaryDark"
    van:skinChangeEnable="true" />

applySkin(skinIndex);