java - 异步任务 : Can't update UI from publishProgress. 错误 : Only the original thread that created a view hierarchy can touch its views.

Question

Developer.Android 说 PublishProgress 驻留在 UI 线程中，因此我应该能够从 Publish Progress 更改 UI。

但是，我得到这个错误:

android.view.ViewRootImpl$CalledFromWrongThreadException: 只有创建 View 层次结构的原始线程可以触及它的 View

关于这段代码:

通话 Activity

public class AttendanceOperations extends AppCompatActivity {

TextView remaningTimeTV;
databaseTimeTableClass aDB;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_attendance_operations);



    Calendar c = Calendar.getInstance();
    int minute = c.get(Calendar.MINUTE);
    int hours = c.get(Calendar.HOUR);

    remaningTimeTV = (TextView)findViewById(R.id.remaningTime);
    aDB = new databaseTimeTableClass(this);

    String currentClass = aDB.attendanceSubjectView(hours, minute);

    TextView newClass = (TextView)findViewById(R.id.nextclass);
    newClass.setText(currentClass);

    new timerForUpComing(remaningTimeTV).execute();

}}

异步类

public class timerForUpComing extends AsyncTask <Void, Integer, Void>{

public boolean a = true;
public int differenceMinute;
public int currentMinute;

TextView timeView;

public timerForUpComing(TextView timeRem)
{
    this.timeView=timeRem;
}

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



    while (a)
    {
        Calendar c = Calendar.getInstance();
        currentMinute = c.get(Calendar.SECOND);
        differenceMinute = 60 - currentMinute;
        Log.d("d ", String.valueOf(differenceMinute));
        publishProgress(differenceMinute);
        try {
           Thread.sleep(999);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        if(differenceMinute==1)
            a = false;
    }

   return null;
}


public void publishProgress(int remaining)
{
    timeView.setText(String.valueOf(remaining));

} }

我正在通过 Constructor 将 TextView 从类 AttendanceOperations 传递到 timeForUpComing，因此我可以从 PublishProgress 更新它。

这似乎不起作用。

Answer 1

Android says PublishProgress resides in UI Thread and thus I should be able to alter the UI from Publish Progress.

AsyncTask 有自己的 publishProgress() 方法。您不实现 publishProgress()。您调用 publishProgress()。您实现 onProgressUpdate()，然后在onProgressUpdate() 中，您可以更新您的用户界面。

这包含在 the documentation 中.

所以，改变:

public void publishProgress(int remaining)
{
    timeView.setText(String.valueOf(remaining));

}

到:

@Override
public void onProgressUpdate(Integer... remaining) {
    timeView.setText(remaining.toString());
}

此外，this sample app演示了 AsyncTask 的使用，包括调用 publishProgress() 和实现 onProgressUpdate()。