android - Simple Runnable experiment Works on AVD but not on hardware device -

i'm beginner @ both android development , stackoverflow please don't shoot me if step on toes ! trying simple app working user pushes button , displayed integer increments while button held down, , button stays when button released. ground breaking stuff !

so went following approach :

public class mainactivity extends activity { button pushbtn; textview textview,inc_txt; string tag ="button act"; int inc_val =0; public handler myhandler=null; boolean finishedthread = false; boolean threadrunning = false; @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);      setcontentview(r.layout.activity_main);      log.i(tag, "in oncreate");  } @override protected void onstart() {     // todo auto-generated method stub     super.onstart();     log.i(tag, "in onstart");     pushbtn=(button)findviewbyid(r.id.btn_push);     log.i(tag, "in onstart 1");     textview=(textview)findviewbyid(r.id.testtext);     inc_txt=(textview)findviewbyid(r.id.increment_text);       pushbtn.setontouchlistener(new ontouchlistener() {          @override         public boolean ontouch(view v, motionevent button_event) {              log.i(tag, "in ontouch event");             switch (button_event.getaction()) {             case motionevent.action_down:                  log.i(tag, " ..down");                 textview.settext("button down");                 if(myhandler!=null)                 {                     log.i(tag, "handle not null");                     return true;                 }                 myhandler=new handler();                 log.i(tag, "postingaction original");                 myhandler.postdelayed(pushedaction, 250);                   return true;              case motionevent.action_up:                  textview.settext("button up");                 myhandler.removecallbacks(pushedaction);                 myhandler=null;                   return true;               default:                 textview.settext("default");                 myhandler=null;                 break;             }             return false;         }       });     log.i(tag, "in onstart 3"); }  runnable pushedaction= new runnable() {      @override     public void run() {         inc_txt.settext(integer.tostring(inc_val));         inc_val++;         log.i(tag, "postingaction repeat");         myhandler.postdelayed(this, 250);         // todo auto-generated method stub      } }; 

and happy days works on avd (4.2.2). (its button , 2 textviews)

but when went put onto nexus 4 (4.3), original postdelayed (in "onstart") works fine , second postdelayed, recursive call in runnable throws null pointer exception.

see logcat:

08-08 10:08:14.245: i/button act(19992): in ontouch event 08-08 10:08:14.245: i/button act(19992): ..down 08-08 10:08:14.245: i/button act(19992): postingaction original 08-08 10:08:14.275: i/button act(19992): in ontouch event 08-08 10:08:14.385: i/button act(19992): in ontouch event 08-08 10:08:14.405: i/button act(19992): in ontouch event 08-08 10:08:14.425: i/button act(19992): in ontouch event 08-08 10:08:14.495: i/button act(19992): postingaction repeat 08-08 10:08:14.495: d/androidruntime(19992): shutting down vm 08-08 10:08:14.495: w/dalvikvm(19992): threadid=1: thread exiting uncaught exception (group=0x4152c700) 08-08 10:08:14.495: e/androidruntime(19992): fatal exception: main 08-08 10:08:14.495: e/androidruntime(19992): java.lang.nullpointerexception 08-08 10:08:14.495: e/androidruntime(19992): @ com.example.buttonexperiments.mainactivity$1.run(mainactivity.java:94) 08-08 10:08:14.495: e/androidruntime(19992): @ android.os.handler.handlecallback(handler.java:730) 08-08 10:08:14.495: e/androidruntime(19992): @ android.os.handler.dispatchmessage(handler.java:92) 08-08 10:08:14.495: e/androidruntime(19992): @ android.os.looper.loop(looper.java:137) 08-08 10:08:14.495: e/androidruntime(19992): @ android.app.activitythread.main(activitythread.java:5103) 08-08 10:08:14.495: e/androidruntime(19992): @ java.lang.reflect.method.invokenative(native method) 08-08 10:08:14.495: e/androidruntime(19992): @ java.lang.reflect.method.invoke(method.java:525) 08-08 10:08:14.495: e/androidruntime(19992): @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:737) 08-08 10:08:14.495: e/androidruntime(19992): @ com.android.internal.os.zygoteinit.main(zygoteinit.java:553) 08-08 10:08:14.495: e/androidruntime(19992): @ dalvik.system.nativestart.main(native method)

can see doing wrong? appreciated. sorry if made mess of asking question ( logcat .. know )! safe travels !

i think problem might in default case of switch case , in action put myhandler null. there reason why that? create new handler everytime touch , null everytime. why that? put myhandler=new handler(); in oncreate , leave way, no need put null , create new one.