Question

任何人都可以帮助我吗？我显然做错了，我似乎无法弄清楚自己。基本上 doInBackground（）方法没有运行。

这是整个类文件和调用它的代码行

呼叫：

new MyTimer().execute();

文件：

public class MyTimer extends AsyncTask<Object, Object, Object> { 

Timer _timerTask = new Timer();
static int totalSeconds = 1, hour = 0, min = 0, sec = 0;
static String mTimeFormat = "%02d:%02d:%02d";
static String timeTakenString;

@Override
protected Object doInBackground(Object... params) {

        TimerTask timer = new TimerTask() {
            @Override
            public void run() {

                GPSMain.printscreen();
                totalSeconds += 1;
                sec += 1;
                if(sec >= 60) {
                    sec = 0;
                    min += 1;
                    if (min >= 60) {
                        min = 0;
                        hour += 1;
                    }
                }
                timeTakenString = String.format(mTimeFormat, hour, min, sec);
                onPostExecute(timeTakenString);

            }
        };
         (_timerTask).scheduleAtFixedRate(timer,1000,1000);
        return timeTakenString;


}
 protected void onPostExecute(String timeTaken) {
    GPSMain.timer.setText("Time Taken: "+timeTaken);
}
}

编辑1：

logcat的：

06-20 10:18:20.036: DEBUG/AndroidRuntime(312): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<<
06-20 10:18:20.046: DEBUG/AndroidRuntime(312): CheckJNI is ON
06-20 10:18:20.225: DEBUG/AndroidRuntime(312): --- registering native functions ---
06-20 10:18:20.506: DEBUG/ddm-heap(312): Got feature list request
06-20 10:18:20.865: INFO/ActivityManager(52): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=Hartford.gps/.GPSMain }
06-20 10:18:20.925: DEBUG/AndroidRuntime(312): Shutting down VM
06-20 10:18:20.944: DEBUG/dalvikvm(312): DestroyJavaVM waiting for non-daemon threads to exit
06-20 10:18:20.944: DEBUG/dalvikvm(312): DestroyJavaVM shutting VM down
06-20 10:18:20.944: DEBUG/dalvikvm(312): HeapWorker thread shutting down
06-20 10:18:20.944: DEBUG/dalvikvm(312): HeapWorker thread has shut down
06-20 10:18:20.976: DEBUG/jdwp(312): JDWP shutting down net...
06-20 10:18:20.976: INFO/dalvikvm(312): Debugger has detached; object registry had 1 entries
06-20 10:18:20.985: ERROR/AndroidRuntime(312): ERROR: thread attach failed
06-20 10:18:20.985: DEBUG/dalvikvm(312): VM cleaning up
06-20 10:18:21.175: DEBUG/dalvikvm(312): LinearAlloc 0x0 used 638596 of 5242880 (12%)
06-20 10:18:21.495: INFO/ActivityManager(52): Displayed activity Hartford.gps/.GPSMain: 604 ms (total 24251 ms)
06-20 10:18:23.365: INFO/NotificationService(52): enqueueToast pkg=Hartford.gps callback=android.app.ITransientNotification$Stub$Proxy@44ddfa60 duration=1
06-20 10:18:23.545: DEBUG/GpsLocationProvider(52): setMinTime 250
06-20 10:18:23.545: DEBUG/GpsLocationProvider(52): startNavigating
06-20 10:18:24.206: DEBUG/LocationManager(287): removeUpdates: listener = Hartford.gps.Calculations$1@44f03dc0
06-20 10:18:24.206: DEBUG/GpsLocationProvider(52): stopNavigating
06-20 10:18:26.146: WARN/KeyCharacterMap(287): No keyboard for id 0
06-20 10:18:26.146: WARN/KeyCharacterMap(287): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
06-20 10:18:26.616: WARN/IInputConnectionWrapper(97): showStatusIcon on inactive InputConnection

Answer 1

试试这个..

公共类MyAsyncTask扩展了Activity {

public static TextView timer;
private MyTimer asyncTask;

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

    asyncTask = (MyTimer) new MyTimer().execute();
    timer = (TextView) findViewById(R.id.text);

}

public class MyTimer extends AsyncTask<String, Object, String> {

    Timer _timerTask = new Timer();
    int totalSeconds = 1;
    int hour = 0;
    int min = 0;
    int sec = 0;
    final String mTimeFormat = "%02d:%02d:%02d";
    String timeTakenString;
    private String timeTaken;
    @Override
    protected String doInBackground(String... params) {

        TimerTask timer = new TimerTask() {
            @Override
            public void run() {

                MyAsyncTask.printscreen();
                totalSeconds += 1;
                sec += 1;
                if (sec >= 60) {
                    sec = 0;
                    min += 1;
                    if (min >= 60) {
                        min = 0;
                        hour += 1;
                    }
                }
                timeTakenString = String
                        .format(mTimeFormat, hour, min, sec);
                onPostExecute(timeTakenString);

            }
        };
        (_timerTask).scheduleAtFixedRate(timer, 1000, 1000);
        return timeTakenString;

    }

    protected void onPostExecute(String timeTaken) {
        this.timeTaken = timeTaken;
        Message message = new Message();
        message.what = 100;
        mHandler.sendMessage(message);
    }

    Handler mHandler = new Handler() {


        public void handleMessage(Message msg) {
            if (msg.what == 100) {

                timer.setText("Time Taken: " + timeTaken);
            }
        };
    };
}

protected static void printscreen() {
    // TODO Auto-generated method stub

}

}

Answer 2

您在线程中启动线程（计时器是一个线程），这是一个问题。我发现你需要可重复的代码。为什么不使用没有AsyncTask的Timer？它是单独的线程，它不会挂起UI。当然，您需要Handler对象来更新任何UI，因为您无法从另一个UI更新UI，而不能更新UI线程。这样的事情应该有效：

Timer _timerTask = new Timer();
    TimerTask timer = new TimerTask() {
        @Override
        public void run() {
            postExecute.sendEmptyMessage(0); //first UI update              
            totalSeconds += 1;
            sec += 1;
            if(sec >= 60) {
                sec = 0;
                min += 1;
                if (min >= 60) {
                    min = 0;
                    hour += 1;
                }
            }
            timeTakenString = String.format(mTimeFormat, hour, min, sec);
            postExecute.sendEmptyMessage(1); //second UI update
        }
        private Handler postExecute = new Handler(){
            @Override
            public void dispatchMessage(Message msg) {
                super.dispatchMessage(msg);
                if(msg.what == 0)
                    GPSMain.printscreen();
                else if(msg.what == 1)
                    GPSMain.timer.setText("Time Taken: "+timeTaken);
            }
        };
    };
    _timerTask.scheduleAtFixedRate(timer,1000,1000);

Answer 3

您可以在后台使用onProgressUpdate更改TextView文本。

 @Override
        protected void onProgressUpdate(String... values) 
         {
            GPSMain.timer.setText("Time Taken: "+values[0]);
            super.onProgressUpdate(values);
        }

并在publishProgress(timeTakenString)方法中调用此doinBackground。

有关AsyncTask的更多详细信息，请click here

AsyncTask没有执行

3 个答案: