Android Night Mode - themes.xml

1themes.xml

    <!-- ========================== -->
    <!-- Base App Theme -->
    <!-- ========================== -->
    <style name="AppTheme.Base" parent="Theme.AppCompat.NoActionBar">
      <item name="android:windowNoTitle">true</item>
      <item name="windowActionBar">false</item>
      ...
    </style>
    
    <!-- ========================== -->
    <!-- Regular or Light App Theme -->
    <!-- ========================== -->
    <style name="AppTheme.Light" parent="AppTheme.Base">
      <item name="colorPrimary">@color/actionbar_background_color</item>
      <item name="colorPrimaryDark">@color/statusbar_bg_color_filter_none</item>
      ...
    </style>
    
    <!-- ========================== -->
    <!-- Night or Dark App Theme -->
    <!-- ========================== -->
    <style name="AppTheme.Dark" parent="AppTheme.Base">
      <item name="colorPrimary">@color/dark_action_bar_color</item>
      <item name="colorPrimaryDark">@color/dark_status_bar_color</item>
      ...
    </style>

2ThemeUtils.java

public final class ThemeUtils {
  
  private static int mAppTheme;
  
  public static int getAppTheme(){
    mAppTheme = isNightMode() ? R.style.Apptheme_Dark : R.style.Apptheme_Light;
    return mAppTheme;
  }
  
  public static boolean isNightMode(){
    // TODO - Create a time difference logic to detect the daylight and nightmode
    return false;
  }
  
}

3MainActivity.java

public class MainActivity extends Activity {
  
  public void onCreate(Bundle saveInstance) {
    // set the daylight or night theme here  
    setTheme(Utils.getAppTheme());
    // super activity constructor
    super.onCreate(saveInstance);
    // set the content display view or layout
    setContentView(R.layout.activity_main);
    
  }
  
}

4styles.xml

<style name="MyTheme" parent="Theme.AppCompat.DayNight">
   <!-- do something -->
</style>