Android：在onProgressUpdate函數中的AsyncTask中的CalledFromWrongThreadException

Question

這是一個非常簡單的程序，它調用按鈕單擊上的asynctask，這會更改textview。

但在按鈕上單擊它會給出一個CalledFromWrongException。

public class FragmentC extends Fragment { 
public FragmentC() { 
    } 
public View contentViewC; 
@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    contentViewC = inflater.inflate(R.layout.fragment_fragment_b, container, false); 

    Button button = (Button) contentViewC.findViewById(R.id.button1); 
    button.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      if (MainActivity.filepath != "Nothing") { 
       Frequency getFreq=new Frequency(); 
       getFreq.execute(); 
     } 

     } 

    }); 
    return contentViewC; 
} 
private class Frequency extends AsyncTask<Void, Float, Void> { 
    @Override 
    protected Void doInBackground(Void... params) { 
      onProgressUpdate(); 
     return null; 
    } 

    @Override 
    protected void onProgressUpdate(Float... values) { 
     textToChange.setText("Demo"); 
    } 
} 

Answer 1

不要調用onProgressUpdate()直接

您只要致電publishProgress()從doInBackground()，然後AsynchTask呼叫onProgressUpdate()在UI線程。

In Android only in main thread we update the UI 

詳細檢查了這onProgressUpdate() documnet