Android AsyncTask＃2錯誤

我的應用程序不斷崩潰，當我看着我的logcat時，我得到兩組錯誤和我的應用程序崩潰。如果有人能告訴我哪裏出了什麼問題，我會非常感激，我能做些什麼來阻止它。Android AsyncTask＃2錯誤

07-27 11:05:53.647: E/AndroidRuntime(913): FATAL EXCEPTION: AsyncTask #2 
07-27 10:36:54.139: E/AndroidRuntime(775): java.lang.RuntimeException: An error occured while executing doInBackground() 
07-27 10:36:54.139: E/AndroidRuntime(775): at android.os.AsyncTask$3.done(AsyncTask.java:299) 
07-27 10:36:54.139: E/AndroidRuntime(775): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352) 
07-27 10:36:54.139: E/AndroidRuntime(775): at java.util.concurrent.FutureTask.setException(FutureTask.java:219) 
07-27 10:36:54.139: E/AndroidRuntime(775): at java.util.concurrent.FutureTask.run(FutureTask.java:239) 
07-27 10:36:54.139: E/AndroidRuntime(775): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) 
07-27 10:36:54.139: E/AndroidRuntime(775): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) 
07-27 10:36:54.139: E/AndroidRuntime(775): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) 
07-27 10:36:54.139: E/AndroidRuntime(775): at java.lang.Thread.run(Thread.java:856) 
07-27 10:36:54.139: E/AndroidRuntime(775): Caused by: java.lang.NullPointerException 
07-27 10:36:54.139: E/AndroidRuntime(775): at com.theproblemsolver.ListView$LoadAllData.doInBackground(ListView.java:92) 
07-27 10:36:54.139: E/AndroidRuntime(775): at com.theproblemsolver.ListView$LoadAllData.doInBackground(ListView.java:1) 
07-27 10:36:54.139: E/AndroidRuntime(775): at android.os.AsyncTask$2.call(AsyncTask.java:287) 
07-27 10:36:54.139: E/AndroidRuntime(775): at java.util.concurrent.FutureTask.run(FutureTask.java:234) 
07-27 10:36:54.139: E/AndroidRuntime(775): ... 4 more

這是其他錯誤我logcat的是給我...

theproblemsolver.ListView has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{40d0e800 V.E..... R.....ID 0,0-234,72} that was originally added here 
07-27 11:05:56.119: E/WindowManager(913): android.view.WindowLeaked: Activity com.theproblemsolver.ListView has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{40d0e800 V.E..... R.....ID 0,0-234,72} that was originally added here 
07-27 11:05:56.119: E/WindowManager(913): at android.view.ViewRootImpl.<init>(ViewRootImpl.java:354) 
07-27 11:05:56.119: E/WindowManager(913): at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:216) 
07-27 11:05:56.119: E/WindowManager(913): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69) 
07-27 11:05:56.119: E/WindowManager(913): at android.app.Dialog.show(Dialog.java:281) 
07-27 11:05:56.119: E/WindowManager(913): at com.theproblemsolver.ListView$LoadAllData.onPreExecute(ListView.java:85) 
07-27 11:05:56.119: E/WindowManager(913): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586) 
07-27 11:05:56.119: E/WindowManager(913): at android.os.AsyncTask.execute(AsyncTask.java:534) 
07-27 11:05:56.119: E/WindowManager(913): at com.theproblemsolver.ListView.onCreate(ListView.java:52) 
07-27 11:05:56.119: E/WindowManager(913): at android.app.Activity.performCreate(Activity.java:5104) 
07-27 11:05:56.119: E/WindowManager(913): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 
27 11:05:56.119: E/WindowManager(913): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 
07-27 11:05:56.119: E/WindowManager(913): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 
07-27 11:05:56.119: E/WindowManager(913): at android.app.ActivityThread.access$600(ActivityThread.java:141) 
07-27 11:05:56.119: E/WindowManager(913): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
07-27 11:05:56.119: E/WindowManager(913): at android.os.Handler.dispatchMessage(Handler.java:99) 
07-27 11:05:56.119: E/WindowManager(913): at android.os.Looper.loop(Looper.java:137) 
07-27 11:05:56.119: E/WindowManager(913): at android.app.ActivityThread.main(ActivityThread.java:5041) 
07-27 11:05:56.119: E/WindowManager(913): at java.lang.reflect.Method.invokeNative(Native Method) 
07-27 11:05:56.119: E/WindowManager(913): at java.lang.reflect.Method.invoke(Method.java:511) 
07-27 11:05:56.119: E/WindowManager(913): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
07-27 11:05:56.119: E/WindowManager(913): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
07-27 11:05:56.119: E/WindowManager(913): at dalvik.system.NativeStart.main(Native Method

MainActivity

public class MainActivity extends Activity { 

    EditText et; 
    Button getanswer; 

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

     Button getanswer = (Button) findViewById(R.id.button1); 
     getanswer.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View v) { 
      Intent i = new Intent(MainActivity.this, ListView.class); 
      startActivity(i); 
     } 


     }); 
    } 
}

的ListView活動

public class ListView extends ListActivity { 

    private ProgressDialog pDialog; 

    JSONParsser jParser = new JSONParsser(); 
    ArrayList<HashMap<String, String>> questionList; 

    private static String URI = "http://example.com/json";; 

    //JSONObject json = jParser.getJSONFromURI(URI); 

    final String TAG_RESULTS = "ResultsSet"; 
    final String TAG_SUBJECT = "Subject"; 
    final String TAG_NUMANSWERS = "NumAnswers"; 
    final String TAG_QUESTION = "Question"; 
    final String TAG_QUESTION_CONTENT = "Content"; 
    final String TAG_QUESTION_CHOSENANSWER = "ChosenAnswer"; 
    final String TAG_QUESTION_ANSWERS = "Answers"; 

      JSONArray ResultsSet = null; 


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

    questionList = new ArrayList<HashMap<String, String>>(); 

    android.widget.ListView lv = getListView(); 

    new LoadAllData().execute(); 

    lv.setOnItemClickListener(new OnItemClickListener() { 

    @Override 
     public void onItemClick(AdapterView<?> parent, View view,int position, long id) { 


     } 
    }); 

} 

    @Override 
    protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
     super.onActivityResult(requestCode, resultCode, data); 

     if (resultCode == 100) { 
      Intent intent = getIntent(); 
      startActivity(intent); 
      finish(); 
     } 
    } 

    class LoadAllData extends AsyncTask<String, String, String> { 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
      pDialog = new ProgressDialog(ListView.this); 
      pDialog.setMessage("Loading Data. Please wait..."); 
      pDialog.setIndeterminate(false); 
      pDialog.setCancelable(false); 
      pDialog.show(); 
     } 

     protected String doInBackground(String... args) { 

      try { 
        JSONObject json = jParser.getJSONFromURI(URI); 
        ResultsSet = json.getJSONArray(TAG_RESULTS); 

        for(int i = 0; i < ResultsSet.length(); i++) { 
         JSONObject r = ResultsSet.getJSONObject(i); 
         String Subject = r.getString(TAG_SUBJECT); 
         String NumAnswers = r.getString(TAG_NUMANSWERS); 

         JSONObject Question = r.getJSONObject(TAG_QUESTION); 
         String Content = Question.getString(TAG_QUESTION_CONTENT); 
         String ChosenAnswer = Question.getString(TAG_QUESTION_CHOSENANSWER); 
         String Answers = Question.getString(TAG_QUESTION_ANSWERS); 

         HashMap<String, String> map = new HashMap<String, String>(); 

         map.put(TAG_SUBJECT, Subject); 
         map.put(TAG_NUMANSWERS, NumAnswers); 

         questionList.add(map); 
        } 



      } catch (JSONException e) { 
       e.printStackTrace(); 
      } 
      return null; 


     } 


     protected void onPostExecute(String file_URI) { 

      pDialog.dismiss(); 
      runOnUiThread(new Runnable() { 
      public void run() { 
       ListAdapter adapter = new SimpleAdapter(getBaseContext(), questionList, 
         R.layout.row, 
         new String[] { TAG_SUBJECT, TAG_NUMANSWERS }, new int[] { 
         R.id.Subject, R.id.NumAnswers }); 

       setListAdapter(adapter); 



       } 
      }); 

     } 
}}

這是我JSONParsser包含類JSONObject json = jParser.getJSONFromURI(URI);方法

public class JSONParsser { 


    static InputStream is = null; 
    static JSONObject jObj = null; 
    static String json = ""; 
    EditText et; 

    public JSONParsser() { 
    } 

    public JSONObject getJSONFromURI(String URI) { 

     try{ 
     HttpClient client = new DefaultHttpClient(); 
     try { 
      URI website = new URI("http://example.com/json"); 
      HttpGet request = new HttpGet(); 
      request.setURI(website); 
      try { 
       HttpResponse response = client.execute(request); 
      HttpEntity httpEntity = response.getEntity(); 
      is = httpEntity.getContent(); 

      } catch (ClientProtocolException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
     } catch (URISyntaxException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
     return jObj; 

     }finally{} 

    }{ 

    } 

}

來源

2013-07-28 Tommy Kind

嗨！您的NPE正在您的ListView類的第92行中發生。我不會幫你的，因爲它可能是一些json解析的東西，請使用調試器來找出本地變量有哪些值！但是你有另一個錯誤更重要，在你的HTTP方法中，請做到這一點：response.getEntity（）。consumeContent（）。否則，你會用apache垃圾堆滿你的堆。或者，如果你使用apache httpclient> 4.0的東西，做EntityUtils.consume（實體）。另外，請用is.close（）關閉你的流。另外，請避免全局。使用局部變量！ –

我得到一個錯誤下'response.getEntity（）consumeContent（）'，說。「類型不匹配：不能從空轉變爲HtttpEntity」 –

'你嘗試EntityUtils.consume（response.getEntity（））';？檢查這個問題：http://stackoverflow.com/questions/4775618/httpclient-4-0-1-how-to-release-connection –

好吧，我會寫，而不是一個答案：

開始與您指定內容到InputStream中，然後返回，你甚至還沒有分配的JSONObject，所以因此你一個NullPointerException。你必須解析輸入流的內容。我會做這樣的事情，而不是：

HttpEntity httpEntity = response.getHttpEntity(); 
String resultString = EntityUtils.toString(httpEntity); 

httpEntity.consumeContent(); 

return new JSONObject(resultString);

注：上面的代碼沒有捕獲任何異常，你將不得不解決這個問題。

然後你有很多不必要的全局變量，你的全局變量都不需要。將它們轉換爲當地人。同樣請將nullcheck的響應，並讀取響應的statusCode，所以它是一個200返回JSONObject之前。

另外：onPostExecute總是在UI線程上運行，只有doInBackground在另一個線程上。

窗口泄漏是因爲您沒有Override a onDestroy()並關閉您的AsyncTask。做這樣的事情（當你開始AsyncTask時請保留一個參考）：

@Override 
public void onDestroy() { 
    super.onDestroy(); 

    if (myAsyncTask != null) { 
     myAsyncTask.cancel(true); 
     myAsyncTask = null; 
    } 
}

來源

2013-07-28 19:37:09

Android AsyncTask＃2錯誤

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