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在 Android 平台上，界面元素不能在定时器的响应函数里刷新。 以下这段代码中，mButton 的文本并不变化。 public class AndroidTimerDemo extends Activity { private Button mButton; private Timer mTimer; private TimerTask mTimerTask; /* Called when the activity is first created. / @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mButton = (Button) findViewById(R.id.Button01); mTimer = new Timer(); mTimerTask = new TimerTask() { @Override public void run() { Log.d("AndroidTimerDemo", "timer"); Calendar cal = Calendar.getInstance(); mButton.setText(cal.toString()); } }; mTimer.schedule(mTimerTask, 1000, 1000); } } 在 Android 平台上，UI 单元必须在 Activity 的 context 里刷新。 为了达到想要的效果，可以使用 Message Handler。在定时器响应函数里发送条消息，在 Activity 里响应消息并更新文本。 public class AndroidTimerDemo extends Activity { protected static final int UPDATE_TEXT = 0; private Button mButton; private Timer mTimer; private TimerTask mTimerTask; private Handler mHandler; /* Called when the activity is first created. / @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mButton = (Button) findViewById(R.id.Button01); mTimer = new Timer(); mHandler = new Handler(){ @Override public void handleMessage(Message msg) { switch (msg.what){ case UPDATE_TEXT: Calendar cal = Calendar.getInstance(); ...
