在将文本附加到EditText时出现AsyncTask错误

Question

我想将文本附加到从doInBackground返回的Edittext。

我的代码如下所示：

public void openFile() { 
      progressDialog.show(); 


     new AsyncTask<Void,String,Void>(){ 

      @Override 
      protected Void doInBackground(Void... voids) { 
        File file = new File("/some file"); 
        BufferedReader br = new 
          BufferedReader(new FileReader(file)); 
        String line; 

        while ((line = br.readLine()) != null) { 
         onProgressUpdate(line); 
        } 
        br.close(); 
       } catch (IOException e) { 
       } 

      } 
      return null; 
     } 

     @Override 
     protected void onProgressUpdate(String... values) { 

      final String line = values[0].toString(); 

       for (char c : line.toCharArray()) { 
         inputEditText.append(Character.toString(c)); 
       }  

     } 

    @Override 
     protected void onPostExecute(Void val){ 
        progressDialog.dismiss(); 
     } 


    }.execute(); 

} 

如果我删除代码onProgressUpdate然后应用程序是无故障运行。

如何解决这个问题？

错误：

java.lang.RuntimeException: An error occured while executing doInBackground() 
     at android.os.AsyncTask$3.done(AsyncTask.java:200) 
     at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274) 
     at java.util.concurrent.FutureTask.setException(FutureTask.java:125) 
     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308) 
     at java.util.concurrent.FutureTask.run(FutureTask.java:138) 
     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) 
     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) 
     at java.lang.Thread.run(Thread.java:1019) 
Caused by: android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. 
     at android.view.ViewRoot.checkThread(ViewRoot.java:3041) 
     at android.view.ViewRoot.invalidateChild(ViewRoot.java:647) 
     at android.view.ViewRoot.invalidateChildInParent(ViewRoot.java:673) 
     at android.view.ViewGroup.invalidateChild(ViewGroup.java:2511) 
     at android.view.View.invalidate(View.java:5279) 
     at android.widget.TextView.updateAfterEdit(TextView.java:5104) 
     at android.widget.TextView.handleTextChanged(TextView.java:6617) 
     at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:6775) 
     at android.text.SpannableStringBuilder.sendTextChange(SpannableStringBuilder.java:889) 
     at android.text.SpannableStringBuilder.change(SpannableStringBuilder.java:352) 
     at android.text.SpannableStringBuilder.change(SpannableStringBuilder.java:269) 
     at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:432) 
     at android.text.SpannableStringBuilder.append(SpannableStringBuilder.java:259) 
     at android.text.SpannableStringBuilder.append(SpannableStringBuilder.java:28) 
     at android.widget.TextView.append(TextView.java:2334) 
     at android.widget.TextView.append(TextView.java:2321) 
     at com.example.sa.myapplication.MainActivity$7.onProgressUpdate(MainActivity.java:358) 

Answer 1

正在直接从doInBackground打电话onProgressUpdate(line);，你需要使用publishProgress。

变化onProgressUpdate(line);为publishProgress(line);

http://developer.android.com/reference/android/os/AsyncTask.html#publishProgress%28Progress...%29

http://developer.android.com/intl/es/guide/components/processes-and-threads.html