GridView (Android) içinde eşzamansız görüntüler yükleme

Question

Farklı sunuculardan yüklenen resim/metin içeren bir GridView var (sadece URL'yi biliyorum). the tutorial of ryac'u temel alarak kodumu değiştirmeyi denedim. Ben kendi adaptörü modifiye ve adapte deneyin gelmiş

GridView mGridMain = (GridView)findViewById(R.id.gvMain); 
mGridMain.setAdapter(new GAdapter(this, listAppInfo)); 

:

public class GAdapter extends BaseAdapter { 

private Context mContext; 
private List<SiteStaff> mListAppInfo; 
private HashMap<Integer, ImageView> views; 

/** 
    * @param context 
    * @param list 
    */ 
public GAdapter(Context context, List<SiteStaff> list) { 
    mContext = context; 
    mListAppInfo = list; 
} 

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

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

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

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

    SiteStaff entry = mListAppInfo.get(position); 

    if(convertView == null) { 
    LayoutInflater inflater = LayoutInflater.from(mContext); 
    convertView = inflater.inflate(R.layout.list_g, null); 
    } 

    ImageView v; 

    // get the ImageView for this position in the GridView.. 
    v = (ImageView)convertView.findViewById(R.id.ivIcon); 

    //set default image 
    v.setImageResource(android.R.drawable.ic_menu_gallery); 

    TextView tvName = (TextView)convertView.findViewById(R.id.tvName); 
    tvName.setText(entry.getName()); 


    Bundle b = new Bundle(); 
    b.putString("file", "http://www.test.com/mypict.jpg"); 
    b.putInt("pos", position); 

    // this executes a new thread, passing along the file 
    // to load and the position via the Bundle.. 
    new LoadImage().execute(b); 

    // puts this new ImageView and position in the HashMap. 
    views.put(position, v); 


    // return the view to the GridView.. 
    // at this point, the ImageView is only displaying the 
    // default icon.. 
    return v; 

} 




// this is the class that handles the loading of images from the cloud 
// inside another thread, separate from the main UI thread.. 
private class LoadImage extends AsyncTask<Bundle, Void, Bundle> { 

    @Override 
    protected Bundle doInBackground(Bundle... b) { 

    // get the file that was passed from the bundle.. 
    String file = b[0].getString("file"); 

    URL UrlImage; 
    Bitmap bm=null; 
    try { 
    UrlImage = new URL (file); 
    HttpURLConnection connection; 
    connection = (HttpURLConnection) UrlImage.openConnection(); 
    bm= BitmapFactory.decodeStream(connection.getInputStream()); 

    } catch (MalformedURLException e) { 
    // TODO Auto-generated catch block 
    e.printStackTrace(); 
    } catch (IOException e) { 
    // TODO Auto-generated catch block 
    e.printStackTrace(); 
    } 


    // now that we have the bitmap (bm), we'll 
    // create another bundle to pass to 'onPostExecute'. 
    // this is the method that is called at the end of 
    // our task. like a callback function.. 
    // this time, we're not passing the filename to this 
    // method, but the actual bitmap, not forgetting to 
    // pass the same position along.. 

    Bundle bundle = new Bundle(); 
    bundle.putParcelable("bm", bm); 
    bundle.putInt("pos", b[0].getInt("pos")); 
    bundle.putString("file", file); // this is only used for testing.. 

    return bundle; 
    } 

    @Override 
    protected void onPostExecute(Bundle result) { 
    super.onPostExecute(result); 

    // just a test to make sure that the position and 
    // file name are matching before and after the 
    // image has loaded.. 
    Log.d("test", "*after: " + result.getInt("pos") + " | " + result.getString("file")); 

    // here's where the photo gets put into the 
    // appropriate ImageView. we're retrieving the 
    // ImageView from the HashMap according to 
    // the position.. 
    ImageView view = views.get(result.getInt("pos")); 

    // then we set the bitmap into that view. and that's it. 
    view.setImageBitmap((Bitmap) result.getParcelable("bm")); 
    } 

} 

} 

Fakat aşağıda hatadır benim Etkinlik dosyasında

, böyle benim GridView için GAdapter set görüntülenen:

11-16 06:16:08.285: E/AndroidRuntime(517): FATAL EXCEPTION: main 
11-16 06:16:08.285: E/AndroidRuntime(517): java.lang.NullPointerException 
11-16 06:16:08.285: E/AndroidRuntime(517): at common.adapter.GAdapter.getView(GAdapter.java:139) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.widget.AbsListView.obtainView(AbsListView.java:1315) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.widget.GridView.onMeasure(GridView.java:932) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.view.View.measure(View.java:8171) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1012) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.widget.LinearLayout.measureVertical(LinearLayout.java:381) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.widget.LinearLayout.onMeasure(LinearLayout.java:304) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.view.View.measure(View.java:8171) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
11-16 06:16:08.285: E/AndroidRuntime(517): at android.view.View.measure(View.java:8171) 

Şimdiye kadar, ben asla Android bulunan Konular kullandı. Birisi bana yardım ederse minnettar olurum. Sonunda GetView() içinde memba

Answer 1

Eğer

views.put(position, v); 

yapıyoruz Ama views başlatıldı olmadı. Eğer senin GAdapter içinde Yüklenici bu başlatıldı memnun karma harita nesnesi önlemek için

java.lang.NullPointerException alıyorsanız neden senin soru refering olan çek örneği ise

public GAdapter(Context context, List<SiteStaff> list) { 
    mContext = context; 
    mListAppInfo = list; 
    views = new HashMap<Integer, ImageView>(); 

} 

bulacaksınız budur

public ImageAdapter (Context c, String f, ArrayList<HashMap<String, Object>> p) { 
     ... 
     views = new HashMap<Integer, ImageView>(); 
    }