Android中的NullPointException異常

Question

有什麼問題？請參閱上面的代碼。

logcat的錯誤：

04-02 18:14:27.294: E/AndroidRuntime(1931): FATAL EXCEPTION: main 
04-02 18:14:27.294: E/AndroidRuntime(1931): java.lang.NullPointerException 
04-02 18:14:27.294: E/AndroidRuntime(1931):  at com.insidetec.itfeed.EfficientAdapter.getView(EfficientAdapter.java:89) 
04-02 18:14:27.294: E/AndroidRuntime(1931):  at android.widget.AbsListView.obtainView(AbsListView.java:2159) 
04-02 18:14:27.294: E/AndroidRuntime(1931):  at android.widget.ListView.makeAndAddView(ListView.java:1831) 
04-02 18:14:27.294: E/AndroidRuntime(1931):  at android.widget.ListView.fillDown(ListView.java:674) 
04-02 18:14:27.294: E/AndroidRuntime(1931):  at android.widget.ListView.fillFromTop(ListView.java:735) 
04-02 18:14:27.294: E/AndroidRuntime(1931):  at android.widget.ListView.layoutChildren(ListView.java:1652) 
04-02 18:14:27.294: E/AndroidRuntime(1931):  at android.widget.AbsListView.onLayout(AbsListView.java:1994) 
04-02 18:14:27.294: E/AndroidRuntime(1931):  at 

EfficientAdapter.java（適配器顯示的職位，extranting XML）：

public class EfficientAdapter extends BaseAdapter { 
private Activity activity; 
private ArrayList<Post> data; 
private static LayoutInflater inflater = null; 
//public ImageLoader imageLoader; 
ViewHolder holder; 

EfficientAdapter(Activity a, ArrayList<Post> d) { 

    activity = a; 
    data = d; 
    inflater = (LayoutInflater) activity 
      .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
// imageLoader = new ImageLoader(activity.getApplicationContext()); 

} 

@Override 
public int getCount() { 
    return data.toArray().length; 

} 

@Override 
public Object getItem(int position) { 

    return position; 
} 

@Override 
public long getItemId(int position) { 

    return position; 
} 

public static class ViewHolder { 
    public TextView label; 
    public TextView addr; 
    public ImageView image; 
} 

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

    if (convertView == null) { 
     vi = inflater.inflate(R.layout.rows, null); 
     holder = new ViewHolder(); 
     holder.label = (TextView) vi.findViewById(R.id.title); 
     holder.addr = (TextView) vi.findViewById(R.id.details); 
     holder.image = (ImageView) vi.findViewById(R.id.thumb); 
     vi.setTag(holder); 
    } else 
     holder = (ViewHolder) vi.getTag(); 

    holder.label.setText(data.get(position).getTitle()); 
    holder.addr.setText(data.get(position).getPubDate()); 

//  imageLoader.DisplayImage((data.get(position).getThumbnail()), activity, 
//    holder.image, 72, 72); 
    URL url = null; 
    try { 
     url = new URL((data.get(position).getThumbnail())); 
    } catch (MalformedURLException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
    InputStream content = null; 
    try { 
     content = (InputStream)url.getContent(); 
    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
    Drawable d = Drawable.createFromStream(content , "src"); 
    Bitmap mIcon1 = null; 
    try { 
     mIcon1 = 
       BitmapFactory.decodeStream(url.openConnection().getInputStream()); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
    holder.image.setImageBitmap(Bitmap.createScaledBitmap(mIcon1, 72, 72, false)); 


    return vi; 
} 

我找不到錯誤顯示在日誌中！我想創建一個RSS提要到我的網站。

Answer 1

此行

holder.image.setImageBitmap(Bitmap.createScaledBitmap(mIcon1, 72, 72, false)); 

導致異常，因爲你的mIcon1是null

你不能找回您的圖像這樣

mIcon1 = BitmapFactory.decodeStream(url.openConnection().getInputStream()); 

你可能會得到NetworkOnMainThreadException也NullPointerException，因爲您的mIcon爲空

嘗試使用UniversalImageDownloader