为什么不能在PagerAdapter中调用instantiateItem（）？

Question

我使用PagerAdapter在Viewpager中显示一些图片。但令我困惑的是，＆＃39; instantiateItem（）＆＃39;无法调用，这意味着无法显示图片。

以下是代码：

public class PictureScrollPagerAdapter extends PagerAdapter {

List<ArticleItme> list;
Context context;
DisplayImageOptions options;
ImageLoader imageLoader;

public PictureScrollPagerAdapter(List<ArticleItme> list, Context context) {
    this.list = list;
    this.context = context;
    int screenWidth = ScreenSizeUtil.getScreenWidth(context);
    options = new DisplayImageOptions.Builder()
            .displayer(new MyDisPlay(screenWidth, screenWidth / 100 * 56))
            .showImageForEmptyUri(R.drawable.def_image)
            .showImageOnFail(R.drawable.def_image).cacheInMemory(true)
            .cacheOnDisc(true).build();
    imageLoader = ImageLoader.getInstance();
}

public List<ArticleItme> getList() {
    return list;
}

public void setList(List<ArticleItme> list) {
    this.list = list;
}

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

@Override
public boolean isViewFromObject(View arg0, Object arg1) {
    return arg0 == arg1;
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
    final ArticleItme topshow = list.get(position);
    ImageView image = new ImageView(context);
    image.setScaleType(ImageView.ScaleType.FIT_XY);
    image.setAdjustViewBounds(true);
   /* image.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            if (topshow.getModelid() == 10) {
                Intent intent = new Intent(context, SpecialActivity2.class);
                intent.putExtra("SpecialActivity", topshow);
                context.startActivity(intent);
            } else if (topshow.getModelid() == 2) {
                Intent intent = new Intent(context, PhotosActivity.class);
                intent.putExtra("SpecialActivity", topshow);
                context.startActivity(intent);
            } else if (topshow.getModelid() == 1) {
                Intent intent = new Intent(context, NewsActivity.class);
                intent.putExtra("SpecialActivity", topshow);
                context.startActivity(intent);
            }

        }
    });*/


    imageLoader.displayImage(topshow.getThumb(), image, options);
    ((ViewPager) container).addView(image);
    return image;
}


@Override
public void destroyItem(ViewGroup container, int position, Object object) {
    ((ViewPager) container).removeView((View) object);
}

class MyDisPlay implements BitmapDisplayer {
    private int newWidth;
    private int newHeight;

    public MyDisPlay(int newWidth, int newHeight) {
        this.newHeight = newHeight;
        this.newWidth = newWidth;
    }

    @Override
    public Bitmap display(Bitmap bitmap, ImageView imageView,
                          LoadedFrom loadedFrom) {
        Bitmap scaleImg = BVBitmapUtil
                .scaleImg(bitmap, newWidth, newHeight);
        imageView.setImageBitmap(scaleImg);
        return scaleImg;
    }
}

}

我测试了可以调用＆＃39; getCount（）＆＃39;但是＆＃39; instantiateItem＆＃39;始终无法被称为