ImageView內部NullPointerException適配器

Question

我正在使用ViewPager來保存我的碎片。我有兩個分段查詢不同的碎片。我的片段之一有網格視圖佈局。我已經創建並適配GridView來加載圖像。

這是我的片段

public class FeedsFragment extends Fragment { 
    GridView gridview; 
    List<ParseObject> ob; 
    FeedsGridAdapter adapter; 
    private List<ParseFeeds> phonearraylist = null; 
    View rootView; 

    public static final String TAG = FeedsFragment.class.getSimpleName(); 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     rootView = inflater.inflate(R.layout.feeds_layout, 
       container, false); 
     new RemoteDataTask().execute(); 
     return rootView; 
    } 


    private class RemoteDataTask extends AsyncTask<Void,Void,Void> { 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
     } 

     @Override 
     protected Void doInBackground(Void... params) { 
      // Create the array 
      phonearraylist = new ArrayList<ParseFeeds>(); 
      try { 
       // Locate the class table named "SamsungPhones" in Parse.com 
       ParseQuery<ParseObject> query = new ParseQuery<ParseObject>(
         "AroundMe"); 
       // Locate the column named "position" in Parse.com and order list 
       // by ascending 
       // query.whereEqualTo(ParseConstants.KEY_RECIPIENT_IDS, ParseUser.getCurrentUser().getUsername()); 
       query.orderByAscending("createdAt"); 
       ob = query.find(); 
       for (ParseObject country : ob) { 
        ParseFile image = (ParseFile) country.get("videoThumbs"); 
        ParseFeeds map = new ParseFeeds(); 
        map.setPhone(image.getUrl()); 
        phonearraylist.add(map); 
       } 
      } catch (ParseException e) { 
       Log.e("Error", e.getMessage()); 
       e.printStackTrace(); 
      } 
      return null; 
     } 

     @Override 
     protected void onPostExecute(Void result) { 
      // Locate the gridview in gridview_main.xml 
      gridview = (GridView) rootView.findViewById(R.id.gridview); 
      // Pass the results into ListViewAdapter.java 
      adapter = new FeedsGridAdapter(FeedsFragment.this.getActivity(), 
        phonearraylist); 
      // Binds the Adapter to the ListView 
      gridview.setAdapter(adapter); 
     } 
    } 

} 

我創建的圖像加載到

public static final String TAG = FeedsGridAdapter.class.getSimpleName(); 

    // Declare Variables 
    Context context; 
    LayoutInflater inflater; 
    ImageLoader imageLoader; 
    private List<ParseFeeds> phonearraylist = null; 
    private ArrayList<ParseFeeds> arraylist; 

    public FeedsGridAdapter(Context context, List<ParseFeeds> phonearraylist) { 
     this.context = context; 
     this.phonearraylist = phonearraylist; 
     inflater = LayoutInflater.from(context); 
     this.arraylist = new ArrayList<ParseFeeds>(); 
     this.arraylist.addAll(phonearraylist); 
     imageLoader = new ImageLoader(context); 
    } 

    public class ViewHolder { 
     ImageView phone; 
    } 

    @Override 
    public int getCount() { 
     return phonearraylist.size(); 
    } 

    @Override 
    public Object getItem(int position) { 
     return phonearraylist.get(position); 
    } 

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

    public View getView(final int position, View view, ViewGroup parent) { 
     final ViewHolder holder; 
     if (view == null) { 
      holder = new ViewHolder(); 
      view = inflater.inflate(R.layout.feeds_layout, null); 
      // Locate the ImageView in gridview_item.xml 
      holder.phone = (ImageView) view.findViewById(R.id.videoThumb); 
      view.setTag(holder); 
     } else { 
      holder = (ViewHolder) view.getTag(); 
     } 
     // Load image into GridView 
     imageLoader.DisplayImage(phonearraylist.get(position).getPhone(), 
       holder.phone); 
     // Capture GridView item click 
     view.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View arg0) { 
       // Send single item click data to SingleItemView Class 
       Intent intent = new Intent(context, SingleVideoView.class); 
       // Pass all data phone 
       intent.putExtra("phone", phonearraylist.get(position) 
         .getPhone()); 
       context.startActivity(intent); 
      } 
     }); 
     return view; 
    } 
} 

這裏它給我的NullPointerException上imageLoader.DisplayImage（phonearraylist.get（位置）.getPhone適配器（）， holder.phone）;

當我在另一個項目中運行相同的代碼只有一個Fragment的工作，但是當我在當前項目中使用它與Two Fargments有不同的解析查詢時，它給了我NullPointerException.Please幫助我浪費了5天左右爲了讓它工作，儘可能在我的最後。

這裏是我的ImageLoader的類

MemoryCache memoryCache = new MemoryCache(); 
    FileCache fileCache; 
    private Map<ImageView, String> imageViews = Collections 
      .synchronizedMap(new WeakHashMap<ImageView, String>()); 
    ExecutorService executorService; 
    // Handler to display images in UI thread 
    Handler handler = new Handler(); 

    public ImageLoader(Context context) { 
     fileCache = new FileCache(context); 
     executorService = Executors.newFixedThreadPool(5); 
    } 

    // int stub_id = ; 

    public void DisplayImage(String url, ImageView imageView) { 
     imageViews.put(imageView, url); 
     Bitmap bitmap = memoryCache.get(url); 
     if (bitmap != null) 
      imageView.setImageBitmap(bitmap); 
     else { 
      queuePhoto(url, imageView); 
      imageView.setImageResource(R.drawable.camera_iris); 
     } 
    } 

    private void queuePhoto(String url, ImageView imageView) { 
     PhotoToLoad p = new PhotoToLoad(url, imageView); 
     executorService.submit(new PhotosLoader(p)); 
    } 

    private Bitmap getBitmap(String url) { 
     File f = fileCache.getFile(url); 

     Bitmap b = decodeFile(f); 
     if (b != null) 
      return b; 

     // Download Images from the Internet 
     try { 
      Bitmap bitmap = null; 
      URL imageUrl = new URL(url); 
      HttpURLConnection conn = (HttpURLConnection) imageUrl 
        .openConnection(); 
      conn.setConnectTimeout(30000); 
      conn.setReadTimeout(30000); 
      conn.setInstanceFollowRedirects(true); 
      InputStream is = conn.getInputStream(); 
      OutputStream os = new FileOutputStream(f); 
      Utils.CopyStream(is, os); 
      os.close(); 
      conn.disconnect(); 
      bitmap = decodeFile(f); 
      return bitmap; 
     } catch (Throwable ex) { 
      ex.printStackTrace(); 
      if (ex instanceof OutOfMemoryError) 
       memoryCache.clear(); 
      return null; 
     } 
    } 

    // Decodes image and scales it to reduce memory consumption 
    private Bitmap decodeFile(File f) { 
     try { 
      // Decode image size 
      BitmapFactory.Options o = new BitmapFactory.Options(); 
      o.inJustDecodeBounds = true; 
      FileInputStream stream1 = new FileInputStream(f); 
      BitmapFactory.decodeStream(stream1, null, o); 
      stream1.close(); 

      // Find the correct scale value. It should be the power of 2. 
      final int REQUIRED_SIZE = 100; 
      int width_tmp = o.outWidth, height_tmp = o.outHeight; 
      int scale = 1; 
      while (true) { 
       if (width_tmp/2 < REQUIRED_SIZE 
         || height_tmp/2 < REQUIRED_SIZE) 
        break; 
       width_tmp /= 2; 
       height_tmp /= 2; 
       scale *= 2; 
      } 

      // Decode with inSampleSize 
      BitmapFactory.Options o2 = new BitmapFactory.Options(); 
      o2.inSampleSize = scale; 
      FileInputStream stream2 = new FileInputStream(f); 
      Bitmap bitmap = BitmapFactory.decodeStream(stream2, null, o2); 
      stream2.close(); 
      return bitmap; 
     } catch (FileNotFoundException e) { 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
     return null; 
    } 

    // Task for the queue 
    private class PhotoToLoad { 
     public String url; 
     public ImageView imageView; 

     public PhotoToLoad(String u, ImageView i) { 
      url = u; 
      imageView = i; 
     } 
    } 

    class PhotosLoader implements Runnable { 
     PhotoToLoad photoToLoad; 

     PhotosLoader(PhotoToLoad photoToLoad) { 
      this.photoToLoad = photoToLoad; 
     } 

     @Override 
     public void run() { 
      try { 
       if (imageViewReused(photoToLoad)) 
        return; 
       Bitmap bmp = getBitmap(photoToLoad.url); 
       memoryCache.put(photoToLoad.url, bmp); 
       if (imageViewReused(photoToLoad)) 
        return; 
       BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad); 
       handler.post(bd); 
      } catch (Throwable th) { 
       th.printStackTrace(); 
      } 
     } 
    } 

    boolean imageViewReused(PhotoToLoad photoToLoad) { 
     String tag = imageViews.get(photoToLoad.imageView); 
     if (tag == null || !tag.equals(photoToLoad.url)) 
      return true; 
     return false; 
    } 

    // Used to display bitmap in the UI thread 
    class BitmapDisplayer implements Runnable { 
     Bitmap bitmap; 
     PhotoToLoad photoToLoad; 

     public BitmapDisplayer(Bitmap b, PhotoToLoad p) { 
      bitmap = b; 
      photoToLoad = p; 
     } 

     public void run() { 
      if (imageViewReused(photoToLoad)) 
       return; 
      if (bitmap != null) 
       photoToLoad.imageView.setImageBitmap(bitmap); 
      else 
       photoToLoad.imageView.setImageResource(R.drawable.camera_iris); 
     } 
    } 

    public void clearCache() { 
     memoryCache.clear(); 
     fileCache.clear(); 
    } 

} 

Answer 1

有一個NullPointerException imageLoader.DisplayImage(phonearraylist.get(position).getPhone(), holder.phone);

這導致了可疑空(ImageView) holder.phone。

爲什麼它必須爲空？

因爲它可能不是躺在您膨脹到的視圖內。

所以

您應檢查您是否充氣從資源佈局合理，不作任何的最常見的錯誤就像使用活動/片段的佈局資源，而不是使用適配器的項目佈局。

不客氣。

Answer 2

ImageLoader的初始化像下面這樣

DisplayImageOptions defaultOptions = new DisplayImageOptions.Builder() 
    .cacheOnDisc()//.imageScaleType(ImageScaleType.EXACTLY) 
    .bitmapConfig(Bitmap.Config.RGB_565).build(); 
    ImageLoaderConfiguration.Builder builder = new ImageLoaderConfiguration.Builder(
      this).defaultDisplayImageOptions(defaultOptions).memoryCache(
        new WeakMemoryCache()); 

    Display display = getWindowManager().getDefaultDisplay(); 
    Point size = new Point(); 
    display.getSize(size); 
    int width = size.x; 
    int height = size.y; 
    ImageLoaderConfiguration config = builder.build(); 
    imageLoader = ImageLoader.getInstance(); 
    imageLoader.init(config);