Android ImageLoader从Parse.com获取图像时出现异常

我正在尝试从imageview数组中的Parse.com获取图像。但是，应用程序在ImageLoader类中出现nullpointerException时崩溃。我在parse.com上有5张图片和6张ImageView。一个ImageView在drawable文件夹中设置了一个图像。因此，从Imageviews 1-6数组中的parse动态加载5个图像。家庭活动是：

ImageView ad1,ad2,ad3,ad4,ad5,ad6;   
List<ParseObject> ob;
private ImageView[] imgs = new ImageView[5];
int k=0;
public ImageLoader imgl;

我在

imageView.setImageResource（stub\u id）上获得空指针

请提供帮助。
占位符出现空指针的唯一原因是您的imageview为空…可能是
您必须仔细检查视图是否正确传递

imgl=new ImageLoader(getApplicationContext());
ad1=(ImageView) findViewById(R.id.ad1);
    ad2=(ImageView) findViewById(R.id.ad2);
    ad3=(ImageView) findViewById(R.id.ad3);
    ad4=(ImageView) findViewById(R.id.ad4);
    ad5=(ImageView) findViewById(R.id.ad5);
    ad6=(ImageView) findViewById(R.id.ad6);
     imgs[0] = ad2; 
     imgs[1] = ad3; 
     imgs[2] = ad4; 
     imgs[3] = ad5; 
     imgs[4] = ad6;
try {
        // Locate the class table named "Footer" in Parse.com
        ParseQuery<ParseObject> query = new ParseQuery<ParseObject>("Adverts");
        query.orderByDescending("updatedAt");
        query.whereEqualTo("Status", true);
        ob = query.find();
        for (ParseObject country : ob) {
            ParseFile image = (ParseFile) country.get("imageFile");
            imgl.DisplayImage(image.getUrl(), imgs[k]);
            k=k+1;
            System.out.println("the urls are"+image.getUrl());

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

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

final int stub_id = R.drawable.ic_launcher;

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(stub_id);
    }
}