致命的例外：AsyncTask＃1進程

Question

我正在試圖做一個無限的滾動像Twitter，我使用Android的無限滾動列表視圖，但始終出現此錯誤。

FATAL EXCEPTION: AsyncTask #1 
Process: candel.ramon.cloudy, PID: 14907 
java.lang.RuntimeException: An error occured while executing doInBackground() 
at android.os.AsyncTask$3.done(AsyncTask.java:300) 
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355) 
at java.util.concurrent.FutureTask.setException(FutureTask.java:222) 
at java.util.concurrent.FutureTask.run(FutureTask.java:242) 
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
java.lang.Thread.run(Thread.java:841) 
Caused by: java.lang.NullPointerException 
at candel.ramon.cloudy.TablonCloudy$1$1.doInBackground(TablonCloudy.java:75) 

這是我的課：

public class TablonCloudy extends Activity { 

    // A setting for how many items should be loaded at once from the server 
    private static final int SEVER_SIDE_BATCH_SIZE = 10; 

    private InfiniteScrollListView infiniteScroll; 

    private TablonAdapter tablonAdapter; 
    // cambiar nombre y datos de esta clase 
    private BogusRemoteService bogusRemoteService; 
    private Handler handler; 
    private AsyncTask<Void, Void, List<String>> fetchAsyncTask; 

    private Map<String, Integer> sushiMappings; 
    // formas de cargar 
    private LoadingMode loadingMode = LoadingMode.SCROLL_TO_TOP; 
    private StopPosition stopPosition = StopPosition.START_OF_LIST; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_tablon_cloudy); 
     handler = new Handler(); 

     infiniteScroll = (InfiniteScrollListView) this 
       .findViewById(R.id.infinite_scrollview); 

     infiniteScroll.setLoadingMode(loadingMode); 
     LayoutInflater layoutInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     infiniteScroll.setLoadingView(layoutInflater.inflate(
       R.layout.loading_view, null)); 

     tablonAdapter = new TablonAdapter(new NewPageListener() { 

      @Override 
      public void onScrollNext() { 
       fetchAsyncTask = new AsyncTask<Void, Void, List<String>>() { 
        @Override 
        protected void onPreExecute() { 
         // Loading lock to allow only one instance of loading 
         tablonAdapter.lock(); 
        } 

        @Override 
        protected List<String> doInBackground(Void... params) { 
         List<String> result; 
         // Mimic loading data from a remote service 
         if (loadingMode == LoadingMode.SCROLL_TO_TOP) { 
          result = bogusRemoteService 
            .getNextMessageBatch(SEVER_SIDE_BATCH_SIZE); 
         } else { 
          result = bogusRemoteService 
            .getNextSushiBatch(SEVER_SIDE_BATCH_SIZE); 
         } 
         return result; 
        } 

        @Override 
        protected void onPostExecute(List<String> result) { 
         if (isCancelled() || result == null || result.isEmpty()) { 
          tablonAdapter.notifyEndOfList(); 
         } else { 
          // Add data to the placeholder 
          if (loadingMode == LoadingMode.SCROLL_TO_TOP) { 
           tablonAdapter.addEntriesToTop(result); 
          } 
          // Add or remove the loading view depend on if there 
          // might be more to load 
          if (result.size() < SEVER_SIDE_BATCH_SIZE) { 
           tablonAdapter.notifyEndOfList(); 
          } else { 
           tablonAdapter.notifyHasMore(); 
          } 
          // Get the focus to the specified position when 
          // loading completes 
          if (loadingMode == LoadingMode.SCROLL_TO_TOP) { 
           infiniteScroll 
             .setSelection(result.size() < SEVER_SIDE_BATCH_SIZE ? 0 
               : 1); 

          } 
         } 
        }; 

        @Override 
        protected void onCancelled() { 
         // Tell the adapter it is end of the list when task is 
         // cancelled 
         tablonAdapter.notifyEndOfList(); 
        } 
       }.execute(); 
      } 

      @Override 
      public View getInfiniteScrollListView(int position, 
        View convertView, ViewGroup parent) { 
       // Customize the row for list view 
       if (convertView == null) { 
        LayoutInflater layoutInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
        convertView = layoutInflater.inflate(R.layout.row_demo, 
          null); 
       } 
       String name = (String) tablonAdapter.getItem(position); 
       if (name != null) { 
        TextView rowName = (TextView) convertView 
          .findViewById(R.id.row_name); 
        ImageView rowPhoto = (ImageView) convertView 
          .findViewById(R.id.row_photo); 
        rowName.setText(name); 
        if (loadingMode == LoadingMode.SCROLL_TO_TOP) { 
         rowPhoto.setImageResource(position % 2 == 0 ? R.drawable.conversation_driver 
           : R.drawable.conversation_officer); 
        } else { 
         rowPhoto.setImageResource(sushiMappings.get(name)); 
        } 
       } 
       return convertView; 
      } 
     }); 

     infiniteScroll.setAdapter(tablonAdapter); 

     // Display a toast when a list item is clicked 
     infiniteScroll.setOnItemClickListener(new OnItemClickListener() { 
      public void onItemClick(AdapterView<?> parent, View view, 
        final int position, long id) { 
       handler.post(new Runnable() { 
        @Override 
        public void run() { 
         Toast.makeText(
           TablonCloudy.this, 
           tablonAdapter.getItem(position) + " " 
             + getString(R.string.ordered), 
           Toast.LENGTH_SHORT).show(); 
        } 
       }); 
      } 
     }); 
    } 

任何人都知道的不喜歡Twitter或Facebook的無限滾動視圖，爲什麼會出現這個錯誤或其他圖書館？

Answer 1

你有NullPointerException異常的位置：

TablonCloudy.java:75 

最有可能bogusRemoteService爲null，因爲從你的代碼，它看起來就像是從來沒有指派一個非空值