Android: Accessing UI Element from timer thread
You have to create the Handler
in the UI Thread, i.e. in onCreate
of your Activity
.
Because you create it in the run
method of a background thread, the handler will execute your code in that very same background thread.
You could also initialize your Handler
directly:
public class MyActivity extends Activity{ private Handler handler = new Handler(); //more code}
And then don't use runOnUIThread
:
handler.post(new Runnable() { public void run() { // TODO Auto-generated method stub Butgrp1.get(cnt).setChecked(true); cnt=cnt+1; if(cnt>4) cnt=0; if(cnt>0) // Butgrp1.get(cnt-1).setChecked(false); System.out.println(cnt); } });
EDIT:Ok try this cleaned up code. Because you did not post your full Activity this won't work out of the box:
public class TestActivity extends Activity { private Button button; static int cnt=0; public ArrayList<RadioButton> buttonArray = new ArrayList<RadioButton>(); private Timer timer = new Timer(); protected void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { timer.schedule(new MyTimerTask(), 1000,2000); } }); } private void doButtonStuff(){ buttonArray.get(cnt).setChecked(true); cnt=cnt+1; if(cnt>4){ cnt=0; } if(cnt>0){ // Butgrp1.get(cnt-1).setChecked(false); System.out.println(cnt); } } private class MyTimerTask extends TimerTask{ @Override public void run() { runOnUiThread(new Runnable() { @Override public void run() { doButtonStuff(); } }); } }}
You don't need to call runOnUIThread inside the handler. By calling post on the Handler instance, the runnable you pass will be executed on the UI thread at some point in the future. Change your code to look like this and it should work:
Handler h=new Handler(); h.post(new Runnable() { public void run() { // TODO Auto-generated method stub Butgrp1.get(cnt).setChecked(true); cnt=cnt+1; if(cnt>4) cnt=0; if(cnt>0) // Butgrp1.get(cnt-1).setChecked(false); System.out.println(cnt); } });