Android：從json的GridView圖像

我有ImageView到GridView的問題，我解析JSON，並從json的URL，並把它放到我的ImageView到GridView，我有這個錯誤，你能幫我嗎？Android：從json的GridView圖像

logcat的

FATAL EXCEPTION: main 
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gazetaimage/com.gazetaimage.MainActivity}: java.lang.NullPointerException 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2309) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2359) 
    at android.app.ActivityThread.access$600(ActivityThread.java:153) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247) 
    at android.os.Handler.dispatchMessage(Handler.java:99) 
    at android.os.Looper.loop(Looper.java:137) 
    at android.app.ActivityThread.main(ActivityThread.java:5202) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:511) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:799) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:566) 
    at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.NullPointerException 
    at com.gazetaimage.ImageAdapter.<init>(ImageAdapter.java:37) 
    at com.gazetaimage.MainActivity.onCreate(MainActivity.java:17) 
    at android.app.Activity.performCreate(Activity.java:5106) 
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2263) 
    ... 11 more

我的代碼在我的AsyncTask我連接到我的JSON文件，並返回的JSONObject，並在ImageAdapter.class我得到這個對象，並投入ImageView的

public class ImageAdapter extends BaseAdapter { 

    public Context mContext; 

    public String[] mThumbs; 

    final static String TAG_ITEM = "item"; 
    final static String TAG_BIG_IMAGE = "big_image"; 

    public ImageAdapter (Context c){ 
     mContext = c; 
     BackTask task = new BackTask(); 
     task.execute(); 

      try { 

       JSONObject result = task.get(); 
       JSONArray jarray = result.getJSONArray(TAG_ITEM); 
       for(int i = 0; i < jarray.length(); i++){ 
        JSONObject jrss = jarray.getJSONObject(i); 

        mThumbs[i] = jrss.getString(TAG_BIG_IMAGE); 
       } 

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


    @Override 
    public int getCount() { 
     return mThumbs.length; 
    } 

    @Override 
    public Object getItem(int position) { 
     return mThumbs[position]; 
    } 

    @Override 
    public long getItemId(int position) { 
     return 0; 
    } 

    @Override 
    public View getView(int position, View convertView, ViewGroup parent) {  

      ImageView imageView; 
      if (convertView == null) { 
       imageView = new ImageView(mContext); 
       imageView.setLayoutParams(new GridView.LayoutParams(85, 85)); 
       imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); 
       imageView.setPadding(8, 8, 8, 8); 
      } else { 
       imageView = (ImageView) convertView; 
      } 

      imageView.setImageURI(Uri.parse(mThumbs[position])); 

      return imageView; 
    }

來源

2012-12-09 03uk

似乎你還沒有初始化mThubs

把下面一行通過JSON數組循環之前：

mThumbs = new String[jarray.length()];

來源

2012-12-09 17:26:46

我相信，你的空指針異常是由不被初始化，mThumbs引起的。在適配器中檢查第37行。

來源

2012-12-09 17:28:40 MrChaz

Android：從json的GridView圖像

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