Question

in my android application i’m using Timer schedule.but getting Timer-0 fatal exception as below.how can i remove it.i have also mentioned code below –

01-28 13:44:41.142: E/AndroidRuntime(1307): FATAL EXCEPTION: Timer-0
01-28 13:44:41.142: E/AndroidRuntime(1307):android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
01-28 13:44:41.142: E/AndroidRuntime(1307):     at android.view.ViewRoot.checkThread(ViewRoot.java:2932)
01-28 13:44:41.142: E/AndroidRuntime(1307):     at android.view.ViewRoot.invalidateChild(ViewRoot.java:642)
01-28 13:44:41.142: E/AndroidRuntime(1307):     at android.view.ViewRoot.invalidateChildInParent(ViewRoot.java:668)
01-28 13:44:41.142: E/AndroidRuntime(1307):     at android.view.ViewGroup.invalidateChild(ViewGroup.java:2511)
01-28 13:44:41.142: E/AndroidRuntime(1307):     at android.view.View.invalidate(View.java:5279)
01-28 13:44:41.142: E/AndroidRuntime(1307):     at android.view.View.setBackgroundDrawable(View.java:7626)
01-28 13:44:41.142: E/AndroidRuntime(1307):     at android.view.View.setBackgroundResource(View.java:7535)
01-28 13:44:41.142: E/AndroidRuntime(1307):     at com.example.iqtest.PlayGame$1.run(PlayGame.java:61)
01-28 13:44:41.142: E/AndroidRuntime(1307):     at java.util.Timer$TimerImpl.run(Timer.java:284)

and code is-

protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.next);
    but1=(Button) findViewById(R.id.b1);
    but2=(Button) findViewById(R.id.b2);
    but3=(Button) findViewById(R.id.b3);

    myTimer = new Timer();

    myTimer.schedule(new TimerTask() {      

        @Override
        public void run() {
            Random rand=new Random();
            int num=rand.nextInt(9)+1;

            num = rand.nextInt(buttonIds.length);
            int buttonId = buttonIds[num];
            Button bb=(Button) findViewById(buttonId);

            Drawable a=bb.getBackground();
            if(getResources().getDrawable(R.drawable.happy).equals(a))
             bb.setBackgroundResource(R.drawable.happy);
            else
                bb.setBackgroundResource(R.drawable.whoa);
        }
    },0, 1000);
}

Answer 1

use runOnUiThread for updating UI element from Timertask run Method as :

 myTimer.schedule(new TimerTask() {      

 @Override
 public void run() {
  Current_Activity.this.runOnUiThread(new Runnable() {
    public void run() {
        // update UI here
    }
 });
 }
},0, 1000);