自定義列表視圖與ImageView的

我從圖像下載代碼， http://android-developers.blogspot.com/2010/07/multithreading-for-performance.html 令我困惑的是，他是怎麼得到的ImageView視圖從ImageDownloader下載（）沒有返回值回來？自定義列表視圖與ImageView的

public class ImageAdapter extends BaseAdapter { 
... 
public View getView(int position, View view, ViewGroup parent) { 
     if (view == null) { 
      view = new ImageView(parent.getContext()); 
      view.setPadding(6, 6, 6, 6); 
     } 

     imageDownloader.download(URLS[position], (ImageView) view); 

     return view; 
    } 
.. 


public class ImageDownloader { 
    ... 
    private void forceDownload(String url, ImageView imageView) { 
    .... 
    case CORRECT: 
        task = new BitmapDownloaderTask(imageView); 
        DownloadedDrawable downloadedDrawable = new DownloadedDrawable(task); 
        imageView.setImageDrawable(downloadedDrawable); 
        imageView.setMinimumHeight(156); 
        task.execute(url);

來源

2014-04-16 james