java - SharedPreferences doesn't update preferences immediately. Requires app restart -

i trying update app layout based on user preference. after preference made, app requires restart preference come effect. want happen without restart. here activity class.

public class mainactivity extends activity implements onclicklistener {  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.mainactivity);     sharedpreferences getprefs = preferencemanager             .getdefaultsharedpreferences(getbasecontext());          theme  = getprefs.getstring("themelist", "0");     switch(theme){     case "0":         setcontentview(r.layout.mainactivity);         break;     case "1":         setcontentview(r.layout.mainactivity_black);         break;     }             initialize();     setclicklisteners();         } 

in way read preferences @ start-up because calling methods in oncreate. if want when change happens have register listner in activity , unregister in ondestroy(). see registeronsharedpreferencechangelistener() method of sharedpreferences.