refresh - Android invalidate() not updating textView -

i'm trying make textview update alongside timed loop. i've tried making invalidate() every time loops. seems work, app crashes when timer starts.

here's loop:

private timer timer; private timertask timertask = new timertask() {     @override     public void run() {         thango += 10;         textypoo.settext(integer.tostring(thango));         textypoo.invalidate();     } };  public void start() {     if (timer != null) {         return;     }     timer = new timer();     timer.scheduleatfixedrate(timertask, 0, 2000); } 

here oncreate initialize stuff:

@override protected void oncreate(bundle savedinstancestate) {      super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_second);     intent intent = getintent();     textypoo = (textview)findviewbyid(r.id.textmcview);  } 

here 2 onclick method. 1 updates textview whenever press it, , calls timer:

 public void sendthestuff(view view) {     setcontentview(r.layout.activity_second);     textypoo = (textview) findviewbyid(r.id.textmcview);     thango++;     message = integer.tostring(thango);     textypoo.settext(message);   }  public void bazinga(view view) {     start(); } 

replace:

private timertask timertask = new timertask() {     @override     public void run() {         thango += 10;         textypoo.settext(integer.tostring(thango));         textypoo.invalidate();     } }; 

to:

private timertask timertask = new timertask() {     @override     public void run() {         runonuithread(new runnable() {             @override             public void run() {                 thango += 10;                 textypoo.settext(integer.tostring(thango));                 textypoo.invalidate();             }         });     } };