致命异常：＃的AsyncTask 1，了java.lang.RuntimeException：在执行doInBackground（）

Question

我想从一个Web服务得到JSON对象，并在列表视图中显示，

，这是我的代码时出错：

public class MainActivity extends Activity { 

    private JsonObject data = null; 
    private JsonObject response = null; 
    private JsonArray records = null; 
    private JsonObject record = null; 
    private ArrayList<SearchResults> results = null; 
    SearchResults sr1 = null; 

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

     ArrayList<SearchResults> searchResults = GetSearchResults(); 

     final ListView lv1 = (ListView) findViewById(R.id.ListView01); 
     lv1.setAdapter(new MyCustomBaseAdapter(this, searchResults)); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.main, menu); 
     return true; 
    } 

    private ArrayList<SearchResults> GetSearchResults() { 
     results = new ArrayList<SearchResults>();  
     new GetResults().execute(""); 

     return results; 
    } 

    private class GetResults extends AsyncTask<String, Void, String> { 

     @Override 
     protected String doInBackground(String... params) { 

      Map<String, String> callArgs = new HashMap<String, String>(1); 

      callArgs.put("suuid", "dtr0bdQGcqwSh3QO7fVwgVfBNWog6mvEbAyljlLX9E642Yfmur"); 

      try { 
       response = EventPulseCloud.call("ListEvents", callArgs); 
      } catch (HttpClientException e) { 
       e.printStackTrace(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } catch (JsonException e) { 
       e.printStackTrace(); 
      } 

      return response.get("Type").toString(); 
     } 

     protected void onPostExecute(String result) { 

      if(result.equals("success")) { 

       data = (JsonObject) response.get("Data"); 
       records = (JsonArray) data.get("Records"); 

       try { 
        records = response.getObject ("Data").getArray ("Records"); 
       } catch (JsonException e) { 
        e.printStackTrace(); 
       } 

       for(int i = 0; i < records.count(); i ++) { 
        record = (JsonObject) records.get(i); 

        sr1 = new SearchResults(); 
        sr1.setAddress(record.get("address").toString()); 
        sr1.setStartingDate(record.get("StartingDate").toString()); 
        sr1.setTicketCategories(record.get("ticketCategories").toString()); 
       results.add(sr1); 

       } 

      } 
     } 

    } 

} 

，我得到这个在logcat中：

06-05 15:53:39.765: E/AndroidRuntime(10012): FATAL EXCEPTION: AsyncTask #1 
06-05 15:53:39.765: E/AndroidRuntime(10012): java.lang.RuntimeException: An error occured while executing doInBackground() 
06-05 15:53:39.765: E/AndroidRuntime(10012): at android.os.AsyncTask$3.done(AsyncTask.java:299) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at java.util.concurrent.FutureTask.setException(FutureTask.java:124) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at java.util.concurrent.FutureTask.run(FutureTask.java:137) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at java.lang.Thread.run(Thread.java:856) 
06-05 15:53:39.765: E/AndroidRuntime(10012): Caused by: java.lang.NullPointerException 
06-05 15:53:39.765: E/AndroidRuntime(10012): at com.example.listview.MainActivity$GetResults.doInBackground(MainActivity.java:73) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at com.example.listview.MainActivity$GetResults.doInBackground(MainActivity.java:1) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at android.os.AsyncTask$2.call(AsyncTask.java:287) 
06-05 15:53:39.765: E/AndroidRuntime(10012): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305) 
06-05 15:53:39.765: E/AndroidRuntime(10012): ... 5 more 
06-05 15:53:40.050: I/Process(10012): Sending signal. PID: 10012 SIG: 9 

在logcat中，该行：MainActivity.java:73是：

return response.get("Type").toString(); 

一切似乎是正确的，我...请，你对此有什么想法？谢谢:)

编辑： 当我尝试这个代码在java中：

Map<String, String> callArgs = new HashMap<String, String>(1); 
    callArgs.put("suuid", "dtr0bdQGcqwSh3QO7fVwgVfBNWog6mvEbAyljlLX9E642Yfmur"); 
    response = EventPulseCloud.call("ListEvents", callArgs); 

    if(response.get("Type").equals("success")) { 
     JsonArray records = response.getObject ("Data").getArray ("Records"); 
     for (int i = 0; i < records.count(); i++) { 
       JsonObject record = (JsonObject)records.get (i); 
       System.out.print(record.get("ticketCategories").toString()); 
     } 
    } 
    else 
     System.out.println("No"); 

，并在屏幕上显示：

[ “SingleDay”] [ “SingleDay”] [“普通票”]

它的确表示它返回了一些内容。

Answer 1

我猜response.get("Type")的结果为空。在尝试使用它之前，你应该确实检查返回的结果。

Answer 2

response.get("Type")返回null。确保你正在寻找正确的东西（也许它是“类型”而不是“类型”？），如果没有别的，添加一些空检查。

Object typeObj = response.get("Type"); 
if (typeObj != null) { 
    return typeObj.toString(); 
} 
return null;