从json获取缩略图Android

我从json获取缩略图。我已经解析了json并加载了缩略图图片，但是我的应用程序一旦打开应用程序就会崩溃。 LogCat在AppController.getInstance().getImageLoader()中显示NullpointerException。我参考了here。从json获取缩略图Android

代码：

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.layout_sales_return); 
private class MyAdapter extends BaseAdapter { 
    private LayoutInflater inflater = null; 
    private ViewHolder holder = null; 
    private Model_BarcodeDetail data; 
    ImageLoader imageLoader = AppController.getInstance().getImageLoader(); // getting NullPointerException here 

    public MyAdapter() { 
     inflater = LayoutInflater.from(Activity_Sales_Return.this); 
    } 

    @Override 
    public int getCount() { 
     // TODO Auto-generated method stub 
     return list.size(); 
    } 

    @Override 
    public Object getItem(int position) { 
     // TODO Auto-generated method stub 
     return list.get(position); 
    } 

    @Override 
    public long getItemId(int position) { 
     // TODO Auto-generated method stub 
     return position; 
    } 

    @Override 
    public boolean isEnabled(int position) { 
     // TODO Auto-generated method stub 
     return true; 
    } 

    @Override 
    public View getView(final int position, View convertView, 
      final ViewGroup parent) { 
     try { 
      if (convertView == null) { 
       holder = new ViewHolder(); 
       inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
       convertView = inflater.inflate(
         R.layout.table_row_sales_return, null); 

       if (imageLoader == null) 
        imageLoader =  
        AppController.getInstance().getImageLoader(); 
       holder.thumbNail = (NetworkImageView) convertView 
         .findViewById(R.id.thumbnail); 


       convertView.setTag(holder); 
      } else { 
       holder = (ViewHolder) convertView.getTag(); 
      } 

      data = (Model_BarcodeDetail) getItem(position); 
      scannedBarcode = list.get(position).getBarcode(); 

      } 
      } 
      }

解析JSON代码：

public Model_BarcodeDetail GetBarcodeDetail(String api_token, String barcode) { 
    HttpClient httpClient = new DefaultHttpClient(); 
    HttpPost postRequest = new HttpPost(Utility.BASE_URL 
      + "?q=webservice/pdt/barcode_detail&token=" + api_token 
      + "&barcode=" + barcode + "&return=json"); 

    String result = ""; 
    Model_BarcodeDetail data = null; 

    try { 
     ResponseHandler<String> responseHandler = new BasicResponseHandler(); 
     result = httpClient.execute(postRequest, responseHandler); 
     JSONObject jsonObj = new JSONObject(result); 
     JSONObject obj1 = jsonObj.getJSONObject("t2tapi"); 
     boolean error = obj1.has("errors"); 
     if (!error) { 
      data = new Model_BarcodeDetail(); 
      data.setDatetime(obj1.getString("datetime")); 
      data.setSuccess(obj1.getString("success")); 
      JSONObject obj2 = obj1.getJSONObject("data"); 
      data.setName(obj2.getString("name")); 

      data.setThumbnailUrl(obj2.getString("image")); 

     } 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 
    return data; 
}

的Json logcat的警告：

04-01 11:20:26.834: W/System.err(3844): org.json.JSONException: No value for image 
04-01 11:20:26.854: W/System.err(3844):  at org.json.JSONObject.get(JSONObject.java:355) 
04-01 11:20:26.854: W/System.err(3844):  at org.json.JSONObject.getString(JSONObject.java:515) 
04-01 11:20:26.854: W/System.err(3844):  at com.example.pdt.Activity_Sales_Return.GetBarcodeDetail(Activity_Sales_Return.java:3282) 
04-01 11:20:26.864: W/System.err(3844):  at com.example.pdt.Activity_Sales_Return$BackgroundTask.doInBackground(Activity_Sales_Return.java:3186) 
04-01 11:20:26.864: W/System.err(3844):  at com.example.pdt.Activity_Sales_Return$BackgroundTask.doInBackground(Activity_Sales_Return.java:1) 
04-01 11:20:26.864: W/System.err(3844):  at android.os.AsyncTask$2.call(AsyncTask.java:288) 
04-01 11:20:26.864: W/System.err(3844):  at java.util.concurrent.FutureTask.run(FutureTask.java:237) 
04-01 11:20:26.864: W/System.err(3844):  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) 
04-01 11:20:26.864: W/System.err(3844):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
04-01 11:20:26.864: W/System.err(3844):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
04-01 11:20:26.864: W/System.err(3844):  at java.lang.Thread.run(Thread.java:841)

原始JSON：

<?xml version="1.0" encoding="UTF-8"?> 
    <skudetail> 
     <datetime>Wed, 30 Mar 2016 07:13:26 +0000</datetime> 
    <success>1</success> 
    <data> 
    <name>AM X COL38/44</name> 
    <reference>000086</reference> 
    <description>EB 3 X COL DURA 38/44</description> 
    <barcode>000086004004</barcode> 
    <price>24.00</price> 
    <color>NAVY S</color> 
    <size>40</size> 
    <stock>11</stock> 
    <branch>MDT</branch> 
    <supplier>KAY</supplier> 
    <supplier_name>DURABLEPRESS BY KAYMANS</supplier_name> 
    <location></location> 
    <basesell></basesell> 
    <vat>A</vat> 
    <avg_cost>5.600</avg_cost> 
    <last_cost>0.000</last_cost> 
    <next_cost>5.600</next_cost> 
    <group_code>MEN</group_code> 
    <alias_code></alias_code> 
    <type>TRF</type> 
    <remarks1>x</remarks1> 
    <remarks2></remarks2> 
    <listed_days></listed_days> 
    <title></title> 
    <type_name>FLAT FRONT TROUSERS</type_name> 
    <user1_name></user1_name> 
    <user2_name></user2_name> 
    <meta_keywords></meta_keywords> 
    <meta_description></meta_description> 
    <image>http://staging.gait- 
way.com/files/product/32106/1459320344_410cCvu-IsL._UX466_.jpg</image> 
</data> 

</skudetail>

来源

2016-04-01 Sheena Tyagi

发布异常堆栈跟踪 – crashOveride

您声明'AppController'作为应用程序在您的显式...？ –

你会粘贴getImageLoader（）的定义吗？确保你的AppController对象不为空 –