Android：用定时器刷 timer 新界面
16lz
2021-12-04
Android：用定时器刷 timer 新界面
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(); mButton.setText(cal.toString()); break; } } }; mTimerTask = new TimerTask() { @Override public void run() { Log.d("AndroidTimerDemo", "timer"); mHandler.sendEmptyMessage(UPDATE_TEXT);/* // It doesn't work updating the UI inside a timer. Calendar cal = Calendar.getInstance(); mButton.setText(cal.toString());*/ } }; mTimer.schedule(mTimerTask, 1000, 1000); }}更多相关文章
- cocos2d-x3.0beta版+NDK-r9b在android上的启动过程
- Android中Message机制的灵活应用
- android相机预览
- android中的recovery模式
- Windows 下 Android(安卓)NDK 环境配置
- [Android]PhoneGap源码分析——CallbackServer异步回调
- Android(安卓)MediaExtractor 浅析
- IntentService简介
- Android(安卓)JB 4.2 中InputManager 启动过程解析 -- 1