JSON對象不打印到屏幕

我包含的代碼是我的AsyncTask獲取來自URL的JSON並試圖解析它並將信息輸出到屏幕上的TextViews。我假設問題在於實際將JSON信息傳遞給字符串並輸出它的onPostExecute塊，但我無法弄清楚我做錯了什麼。我昨晚部分工作，但只打印0和空。我做了一些改變，現在我在這裏。JSON對象不打印到屏幕

class GetStats extends AsyncTask<String, String, JSONObject> { 

    private String api_key="d96236d2-6ee3-4cfd-afa7-f41bdbc11128"; 
    String region = MainActivity.region.toLowerCase(); 
    String name = MainActivity.name; 
    String url = null; 
    String encodedName = null; 
    String encodedKey = null; 
    String encodedRegion = null; 

    // JSON Node Names 
    String TAG_ID = "id"; 
    String TAG_NAME = "name"; 
    String TAG_PROFILEICONID = "profileIconId"; 
    String TAG_REVISIONDATE = "revisionDate"; 
    String TAG_SUMMONERLEVEL = "summonerLevel"; 

    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     try { 
      textId = (TextView) findViewById(R.id.id); 
      textName = (TextView) findViewById(R.id.name); 
      textProfileIconId = (TextView) findViewById(R.id.profileIconId); 
      textRevisionDate = (TextView) findViewById(R.id.revisionDate); 
      textSummonerLevel = (TextView) findViewById(R.id.summonerLevel); 
      encodedName = URLEncoder.encode(name, "UTF-8"); 
      encodedKey = URLEncoder.encode(api_key, "UTF-8"); 
      encodedRegion = URLEncoder.encode(region, "UTF-8"); 
      url = "https://prod.api.pvp.net/api/lol/" + encodedRegion + "/v1.4/summoner/by-name/" + encodedName + "?api_key=" + encodedKey; 

     } catch (UnsupportedEncodingException e) { 
      e.printStackTrace(); 
     } 

    } 

    @Override 
    protected JSONObject doInBackground(String... arg0) { 
     JSONParser jParser = new JSONParser(); 

     // Get JSON from URL 
     JSONObject json = jParser.getJSONFromUrl(url); 
     JSONObject jb = null; 

     try { 
      jb = json.getJSONObject(encodedName); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
     return jb; 
    } 

    @Override 
    protected void onPostExecute(JSONObject json) { 
     try { 
      // Storing JSON item to String 
      String id = json.getString(TAG_ID); 
      String name = json.getString(TAG_NAME); 
      String icon = json.getString(TAG_PROFILEICONID); 
      String revDate = json.getString(TAG_REVISIONDATE); 
      String sumLevel = json.getString(TAG_SUMMONERLEVEL); 

      // Putting JSON data in TextViews 
      textId.setText(id); 
      textName.setText(name); 
      textProfileIconId.setText(icon); 
      textRevisionDate.setText(revDate); 
      textSummonerLevel.setText(sumLevel); 

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

JSON預期結果例如：

{"nv43":{"id":23591778,"name":"NV43","profileIconId":22,"summonerLevel":30,"revisionDate":1396737099000}}

錯誤：

04-07 13:32:18.359 22875-22875/? E/AndroidRuntime﹕ FATAL EXCEPTION: main 
    Process: edu.appdesign.leaguestats, PID: 22875 
    java.lang.NullPointerException 
      at edu.appdesign.leaguestats.StatsActivity$GetStats.onPostExecute(StatsActivity.java:110) 
      at edu.appdesign.leaguestats.StatsActivity$GetStats.onPostExecute(StatsActivity.java:53) 
      at android.os.AsyncTask.finish(AsyncTask.java) 
      at android.os.AsyncTask.access$600(AsyncTask.java) 
      at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java) 
      at android.os.Handler.dispatchMessage(Handler.java) 
      at android.os.Looper.loop(Looper.java) 
      at android.app.ActivityThread.main(ActivityThread.java) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:515) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java) 
      at dalvik.system.NativeStart.main(Native Method)

來源

2014-04-07 Nate

{ // json object node 
    "nv43": { // jsonobject nv43 
     "id": 23591778, 
     "name": "NV43", 
     "profileIconId": 22, 
     "summonerLevel": 30, 
     "revisionDate": 1396737099000 
    } 
}

你錯過了解析JSONObject NV43。

在doInBackground

JSONObject json = jParser.getJSONFromUrl(url); 
JSONObject jb = json.getJSONObject("nv43"); 
return jb;

來源

2014-04-07 17:27:18 Raghunandan

製作在這裏一個NullPointerException該變化結果onPostExecute（）方法：字符串ID = json.getString（TAG_ID）; – Nate

@Nate發佈堆棧跟蹤。 – Raghunandan

@從服務器註銷你的json可以爲空。你確定它不爲空 – Raghunandan

變化像下面

@Override 
    protected void onPostExecute(JSONObject json) { 
     try { 
      JSONObject result = json.getJSONObject("nv43"); // First Create an Object of "nv43" 
      // Storing JSON item to String 
      String id = result.getString(TAG_ID); 
      String name = result.getString(TAG_NAME); 
      // Rest code

來源

2014-04-07 17:34:37

這是相同的，除了你解析'JSONObject nv43.'在onPostExecute – Raghunandan

@Raghunandan我認爲，而不是在doInBackground（）上做它更好地做onPostExecute（）。 –

有多好。事實上，所有的解析都可以在'doInbackground'中完成 – Raghunandan

JSON對象不打印到屏幕

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