在你的情况下，你正在使用线程。因此，你无法从ui线程以外的其他线程更新ui。所以你用
runOnUithread。我建议你使用倒数计时器或处理程序。
1.CountDownTimer
http://developer.android.com/reference/android/os/CountDownTimer.html
这是另一个示例的链接。建议你检查倒计时计时器的链接。
倒数计时器，以分钟和秒为单位
例：
public class MainActivity extends Activity {Button b; TextView tv;@Overrideprotected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); tv = (TextView) findViewById(R.id.textView1); b= (Button) findViewById(R.id.button1); b.setonClickListener(new onClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub startTimer(200000); } });}private void startTimer(long time){ CountDownTimer counter = new CountDownTimer(30000, 1000){ public void onTick(long millisUntilDone){Log.d("counter_label", "Counter text should be changed"); tv.setText("You have " + millisUntilDone + "ms"); } public void onFinish() { tv.setText("DONE!"); } }.start();} }2.你可以使用 Handler
范例：
Handler m_handler;Runnable m_handlerTask ; int timeleft=100;m_handler = new Handler(); m_handlerTask = new Runnable() { @Overridepublic void run() {if(timeleft>=0){ // do stuff Log.i("timeleft",""+timeleft); timeleft--; } else{ m_handler.removeCallbacks(m_handlerTask); // cancel run} m_handler.postDelayed(m_handlerTask, 1000); } }; m_handlerTask.run(); 3.计时器
计时器在其他线程上运行。你应该在ui线程上更新ui。采用runOnUiThread
范例：
int timeleft=100; Timer _t = new Timer(); _t.scheduleAtFixedRate( new TimerTask() { @Override public void run() { runonUiThread(new Runnable() //run on ui thread { public void run() { Log.i("timeleft",""+timeleft);//update ui } }); if(timeleft>==0) { timeleft--; } else { _t.cancel(); } } }, 1000, 1000 ); 
