android - How to switch themes (night mode) without restarting the activity? -

i have made few apps support multiple themes, had restart app when user switches theme, because settheme() needs called before setcontentview().

i okay it, until discovered app. can seamlessly switch between 2 themes, , transitions/animations too!

please give me hints on how implemented (and animations too). thanks!

@alexander hanssen's answer has answered this... don't know why not accepted... maybe because of finish()/startactivity(). voted , tried comment cannot...

anyway, described in terms of styles.

<style name="appthemelight" parent="theme.appcompat.light">     <!-- customize theme here. -->     <item name="android:windowanimationstyle">@style/windowanimationtransition</item> </style> <style name="appthemedark" parent="theme.appcompat">     <!-- customize theme here. -->     <item name="android:windowanimationstyle">@style/windowanimationtransition</item> </style> <!-- set fade in animation on activities default --> <style name="windowanimationtransition">     <item name="android:windowenteranimation">@android:anim/fade_in</item>     <item name="android:windowexitanimation">@android:anim/fade_out</item> </style> 

but instead of finish/start new intent:

intent intent = new intent(this, <yourclass>.class); startactivity(intent); finish(); 

i do:

@override protected void oncreate(bundle savedinstancestate) {      // must before super call or setcontentview(...)     // pick theme day or night settings     settheme(somesettings.get(preffered_theme) ? r.style.appthemelight : r.style.appthemedark);      super.oncreate(savedinstancestate); }  // somewhere in activity button switches theme btn.setonclicklistener(new view.onclicklistener() {     @override     public void onclick(view v) {          // decide theme use day or night , save         somesettings.save(preffered_theme, isday());          activity.this.recreate();     } }); 

the effect shown in video...