錯誤執行異步任務

Question

我有一個viewpager與一些actiontabs每個操作選項卡有自己的佈局。在其中一個佈局中，我有一個按鈕，當點擊一個AsyncTask改變背景 顏色應執行如下所示。

在運行時，我從logcat收到下面的錯誤。

請看看logcat的錯誤，並請讓我知道我在代碼中缺少的東西。

代碼

class AsyncColor extends AsyncTask<String, Integer, String> { 

    @Override 
    protected void onPreExecute() { 
     // TODO Auto-generated method stub 
     super.onPreExecute(); 
    } 

    @Override 
    protected String doInBackground(String... params) { 
     // TODO Auto-generated method stub 
     for (int i = 0; i < params.length; i++){ 
      rl_3.setBackgroundColor(Color.parseColor(params[i])); 
     } 
     return "done"; 
    } 

    @Override 
    protected void onProgressUpdate(Integer... values) { 
     // TODO Auto-generated method stub 
     super.onProgressUpdate(values); 
    } 

    @Override 
    protected void onPostExecute(String result) { 
     // TODO Auto-generated method stub 
     super.onPostExecute(result); 
     btn_asynch.setText(result); 
    } 
} 

@Override 
public void onResume() { 
    // TODO Auto-generated method stub 
    super.onResume(); 

    btn_asynch.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      new AsynchColor().execute(asynchBLUE, asynchGREEN, asynchRED, asynchBLUE1, asynchGREEN1, asynchRED1); 
     } 
    }); 

logcat的：

12-06 13:13:15.049: E/AndroidRuntime(5591): FATAL EXCEPTION: AsyncTask #1 
12-06 13:13:15.049: E/AndroidRuntime(5591): java.lang.RuntimeException: An error occured while executing doInBackground() 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at android.os.AsyncTask$3.done(AsyncTask.java:300) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at java.util.concurrent.FutureTask.setException(FutureTask.java:222) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at java.util.concurrent.FutureTask.run(FutureTask.java:242) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at java.lang.Thread.run(Thread.java:841) 
12-06 13:13:15.049: E/AndroidRuntime(5591): Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:6832) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at android.view.ViewRootImpl.invalidateChildInParent(ViewRootImpl.java:1053) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at android.view.ViewGroup.invalidateChild(ViewGroup.java:4518) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at android.view.View.invalidate(View.java:11687) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at android.view.View.setBackgroundDrawable(View.java:16248) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at android.view.View.setBackground(View.java:16139) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at android.view.View.setBackgroundColor(View.java:16101) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at com.example.viewpagerwithactiontabstest00.Aufgabe_7$AsynchColor.doInBackground(Aufgabe_7.java:72) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at com.example.viewpagerwithactiontabstest00.Aufgabe_7$AsynchColor.doInBackground(Aufgabe_7.java:1) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at android.os.AsyncTask$2.call(AsyncTask.java:288) 
12-06 13:13:15.049: E/AndroidRuntime(5591):  at java.util.concurrent.FutureTask.run(FutureTask.java:237) 

Answer 1

你不能觸摸UI線程元素在doInBackground

@Override 
    protected String doInBackground(String... params) { 
     // TODO Auto-generated method stub 
     for (int i = 0; i < params.length; i++){ 
      publishProgress(params[i]); 
     } 
     return "done"; 
    } 

    @Override 
    protected void onProgressUpdate(Integer... values) { 
     // TODO Auto-generated method stub 
     super.onProgressUpdate(values); 
     rl_3.setBackgroundColor(Color.parseColor(values[i])); 
    } 

Answer 2

您正試圖改變一個線程的視圖w ^這不是UIThread。

您需要將您的

for (int i = 0; i < params.length; i++){ 
     rl_3.setBackgroundColor(Color.parseColor(params[i])); 
    } 

到onPreExecute(runs onUIThread)或onPostExecute(Runs on Ui Thread)或onProgressUpdate不同的邏輯（你可以用publishProgress();打電話。但是如果你的doInBackground是沒有這種空的。我只會建議你清除此的AsyncTask和移動

for (int i = 0; i < params.length; i++){ 
     rl_3.setBackgroundColor(Color.parseColor(params[i])); 
    } 

到您的活動的新方法。我不能說，如果它是更好的由於性能做這樣一個小的凝固酶原直接在UIThread上，或者多次調用onProgressUpdate。我覺得差必須非常小，而你節省大量的代碼行，這使得你的代碼更好看..

瞭解更多的AsyncTask：http://developer.android.com/reference/android/os/AsyncTask.html

而且關於無痛線程教程：http://android-developers.blogspot.co.at/2009/05/painless-threading.html