menu - How to create custom actionbar in android? -

i want create custom actionbar in android, simple code : public class mainactivity extends activity {

    @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);         menubar();     }      public void menubar(){          actionbar mactionbar = getactionbar();         layoutinflater inflater = getlayoutinflater();          view mcustomview    = inflater.inflate(r.layout.menu_bar, null);         imagebutton button  = (imagebutton) mcustomview.findviewbyid(r.id.bt_menu);         button.setonclicklistener(new view.onclicklistener() {              @override             public void onclick(view view) {                 toast.maketext(getapplicationcontext(), "clicked!",toast.length_long).show();             }         });          mactionbar.setcustomview(mcustomview);         mactionbar.setdisplayshowcustomenabled(true);      }  } 

but when running display error :

caused by: java.lang.nullpointerexception: attempt invoke virtual method 'void android.app.actionbar.setcustomview(android.view.view)' on null object reference         @ dot.com.coba.mainactivity.menubar(mainactivity.java:39)         @ dot.com.coba.mainactivity.oncreate(mainactivity.java:21) 

your getactionbar() method returns null, try getsupportactionbar() this:

actionbar mactionbar = getsupportactionbar();