Android應用程序在for循環中崩潰

Question

我從解析數據中收到問題時遇到問題。

日誌說，問題是在這個循環：

q.findInBackground(new FindCallback<ParseObject>() { 

    @Override 
    public void done(List<ParseObject> parseObjects, ParseException e) { 

     for (int i = 0; i < parseObjects.size(); i++) { 

      Comment c = new Comment(); 
      ParseObject o = parseObjects.get(i); 
      c.created = o.getCreatedAt(); 
      c.name = o.getString(Comment.NAME); 
      c.text = o.getString(Comment.TEXT); 
      c.email = o.getString(Comment.EMAIL); 
      c.rating = o.getDouble(Comment.RATING); 
      c.isActive = true; 
      c.place = o.getString(Comment.PLACE); 
      p.comments.add(c); 
     } 
     Comment.increaseDownloaded(); 
    } 
}); 

當我收到小於40點的對象，它工作正常。但是，如果我收到更多，我得到這個錯誤：

05-04 11:25:20.755 1473-1473/com.myapp E/AndroidRuntime﹕ FATAL EXCEPTION: main 
Process: com.myapp, PID: 1473 
java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference 
     at com.myapp.place.PlaceActivity$2$3.done(PlaceActivity.java:362) 
     at com.parse.FindCallback.internalDone(FindCallback.java:45) 
     at com.parse.FindCallback.internalDone(FindCallback.java:31) 
     at com.parse.Parse$4$1.run(Parse.java:792) 
     at android.os.Handler.handleCallback(Handler.java:739) 
     at android.os.Handler.dispatchMessage(Handler.java:95) 
     at android.os.Looper.loop(Looper.java:135) 
     at android.app.ActivityThread.main(ActivityThread.java:5312) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:372) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901) 

任何人都知道什麼是問題？

非常感謝！

Answer 1

檢查parseObjects == null，因爲我相信你會得到parseObjects爲空。

qp.findInBackground(new FindCallback<ParseObject>() { 
        @Override 
        public void done(List<ParseObject> parseObjects, ParseException e) { 
         if (e != null) 
          e.printStackTrace(); 
         if(parseObjects!=null) 
         { 
         for (int i = 0; i < parseObjects.size(); i++) { 
          Photo pp = new Photo(); 
          ParseObject o = parseObjects.get(i); 
          pp.isActive = true; 
          pp.place = o.getString(Photo.PLACE); 
          ParseFile f = o.getParseFile(Photo.PHOTO); 
          pp.url = f.getUrl(); 
          p.photos.add(pp); 
          } 
         Photo.increaseDownloaded(); 
         } 
         else 
         { // Toast here 
         } 
        } 
       });