想在窗体上做一个倒数计时器，请帮看看下面的代码怎么一运行就Forced Closed ?
想通过txtSec显示从60秒倒数到0的效果，请问下面的代码有什么问题？

public class Activity2 extends Activity {
private int Sec;
private TextView txtSec;
private TextView txtview1;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity2);

Sec=60;
txtSec=(TextView) this.findViewById(R.id.txtSec);

handler.post(updateThread);
}


Handler handler=new Handler();

Runnable updateThread=new Runnable(){
public void run(){
Sec--;
txtSec.setText(Sec);
if (Sec>0){
handler.postDelayed(updateThread, 1000);
}else{
handler.removeCallbacks(updateThread);
}
}
};
}

[解决办法]
看下logCat信息报什么错