我有一个ViewPager,其中包含通过Web服务(JSON)获取的10张图片。一开始ViewPager工作得很流畅(好)。
但是当从活动返回并再次打开它时,我遇到了这个错误:
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();
}
}
对于该问题,我尝试了:
@Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
//And
slideShowPager.getAdapter().notifyDataSetChanged();
我从stackoverflow获取的解决方案,但无法工作。
我需要做哪些更改才能使其正常工作?
解决方案
之前我传递了ArrayList,但这次使用了字符串数组(可以工作)。我真的不知道ArrayList出了什么问题。
ArrayAdapter
,也许你没有注意到你修改了传递给适配器的List
。 - Michael Butscher