java - ViewFlipper: flipping at random time intervals using random children -

i want create menu "flips" @ random time intervals between 5 children of viewflipper in random order.

i tried following code , can system.out.println display debugging message logged in logcat @ random time intervals that's working. however, screen in emulator black.

when use setdisplayedchild method in "oncreate" method fixed int, works fine. can me this? many!

public class flippertest extends activity {  int randomtime; int randomchild; viewflipper fliptest; @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_beat_the_game);     viewflipper fliptest = (viewflipper) findviewbyid(r.id.menuflipper);              //this work             //fliptest.setdisplayedchild(3);      while (true){         try {             thread.sleep(randomtime);          } catch (interruptedexception e) {             e.printstacktrace();         }finally{             random timermenu = new random();             randomtime  = timermenu.nextint(6) * 2000;             random childmenu = new random();             randomchild = childmenu.nextint(5);             fliptest.setdisplayedchild(randomchild);              system.out.println("executes loop");         }     }  } 

don't block ui thread thread.sleep()(+ infinite loop), instead use handler, example, make flips:

private viewflipper mfliptest; private handler mhandler = new handler(); private random mrand = new random(); private runnable mflip = new runnable() {      @override     public void run() {         mfliptest.setdisplayedchild(mrand.nextint());         mhandler.postdelayed(this, mrand.nextint(6) * 2000);     }     }  //in oncreate method mfliptest = (viewflipper) findviewbyid(r.id.menuflipper); mhandler.postdelayed(mflip, randomtime);