我有一个 ViewPager，其中 10 个图像来自网络服务 (JSON)，起初 ViewPager 工作顺利(很好)。

但是当从 Activity 中回来并再次打开它时 我得到了这个错误:

java.lang.IllegalStateException: The application's PagerAdapter changed the adapter's contents without calling PagerAdapter#notifyDataSetChanged! 

Expected adapter item count: 10, found: 0 Pager id: com.akm.demo.activities:id/slideShowPager Pager class: class android.support.v4.view.ViewPager 

在主 Activity 类中

if (mSlideShowData != null) { // mSlideShowData is An ArrayList of the Images Which I pass to ImagePagerAdapter
adapter = new ImagePagerAdapter(getContext(), mSlideShowData);
slideShowPager.setAdapter(adapter);

//slideShowPager.invalidate();
((PagerAdapter)slideShowPager.getAdapter()).notifyDataSetChanged(); 
}

 else{
Toast toast = Toast.makeText(getContext(), "No Record Found", Toast.LENGTH_LONG);
toast.setGravity(Gravity.CENTER, 0, 0);
    toast.show();

ImagePagerAdapter.java

public class ImagePagerAdapter extends PagerAdapter {

private Context mContext;
private ImageLoader mImageLoader; // It's use for downloading the image from server
private ArrayList<SlideShowData> slideShowImages; // In this I have all the detail of the image from  API

public ImagePagerAdapter(Context context, ArrayList<SlideShowData> mSlideShowData) {
    mContext = context;
    slideShowImages = mSlideShowData;
    mImageLoader = new ImageLoader(mContext);

}

@Override
public int getItemPosition(Object object) {
     return POSITION_NONE;
}

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

@Override
public boolean isViewFromObject(View view, Object object) {
    return view == ((ImageView) object);
}



@Override
public Object instantiateItem(ViewGroup container, int position) {

    ImageView imageViewSlideShow = new ImageView(mContext);
    int padding = mContext.getResources().getDimensionPixelSize(R.dimen.padding_medium);
    imageViewSlideShow.setPadding(padding, padding, padding, padding);
    imageViewSlideShow.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
    mImageLoader.DisplayImage(ServiceURLs.URL+"/photos/"+slideShowImages.get(position).photo_name, R.drawable.loading, imageViewSlideShow);
    ((ViewPager) container).addView(imageViewSlideShow, 0);
    return imageViewSlideShow;
}

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

}

@Override
public void notifyDataSetChanged() {
        super.notifyDataSetChanged();
}

}

对于解决方案，我尝试过:

@Override
public int getItemPosition(Object object) {
     return POSITION_NONE;
}

//And

slideShowPager.getAdapter().notifyDataSetChanged();

我从 stackoverflow 得到的解决方案，但无法工作。

我需要为工作做出哪些改变？

解决方案

之前我正在传递 ArrayList 但这次是 String Array **(工作)** 真的我不知道 ArrayList 有什么问题

最佳答案

问题的原因寻呼机可以在某些测量期间刷新，在这种情况下将刷新适配器的计数，如果此计数不等于保存的计数，您将看到错误。所以我的解决方案看起来是:

public abstract class ViewPagerCursorAdapter extends PagerAdapter {

    private int mCount;

    public ViewPagerCursorAdapter(Context ctx, Cursor cursor, int resource) {
        super();
        ...
        mCount = cursor.getCount();
        ...
    }

    @Override
    public int getCount() {
        return mCount;
    }

    public Cursor swapCursor(Cursor newCursor) {
        ...
        mCount = newCursor.getCount();
        notifyDataSetChanged();
    }
}

祝你好运。

关于android - ViewPager 第一次工作正常，但再次重新加载时出现错误 java.lang.IllegalStateException？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/17784476/