我有一个RecyclerView（垂直方向），嵌套ViewPager，用于水平滚动图片。
假设我在ViewPager上水平滚动到最后一张图片。然后，我滚动RecyclerView并触发下一个项目的加载。在这里，ViewPager的图片会回到第一张图片。
当适配器收到ViewPager时，如何阻止之前的notifyDataSetChanged()项回到第一张图片？
这是我放在一起展示的一个示例项目： https://github.com/alaouiali/BnbRecyclerView/
以下是我的RecyclerView适配器和PageAdapter
public class VerticalAdapter extends RecyclerView.Adapter<VerticalAdapter.ViewHolder> {
/**
* Contains the String used as a tag for the Log.d
*/
private static final String TAG = VerticalAdapter.class.getSimpleName();
private Context mContext;
private String[] urls = {
"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTqBvZfp5vUzdECuxydMqzkHbv8Io9kc_sGDh6Lb8t58ZEuTWfObw",
"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcR6YRCpLYw6EAsJ8R3HsV5PzmJwVrmA1vZH9eX6-KEPVgbvnmp1VA",
"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTK3k3Mlj_RJQjUU3obJ2K-jAVTS4z-7elTaDxT1k9Q70Kg3Msd",
"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcSnD7v4HtlKQb2BWUoujS6W0T9I0NFcc9FjL9n7J2HnPcHszpUY",
"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcSX_yWO9qRV-tDPJ6dw17tzGFX3hrzJ47gclEkCnNZBzh-CLIgBTw",
"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQFSLufkwkiJbh9Wds3iCmljxxCFjngOsiKh7Ru_G-gJkMZ1dK_",
"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQ_SJdCkLzFz-AM4hmj8fwQWLBbQ8uIe3C923IZAO2mcNdE8dCw",
"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQjXskxWSam8FyCWND63SigsB6pMUg3GKfmPOJEWteahUexrPSB",
"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTwGWksKf3P4nuVBOet_L75b_hgan_pnx-CNsuwOchVgZ-p2XGm",
"https://c4.staticflickr.com/4/3366/4612778012_9c051789bf_b.jpg",
"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRoG9_j2RwXoUZFERhNz-lkQyHCUOgEvoDDVMky9yOaj88Lsc44",
"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRxpM_iLl1d-MVOq5YT2LtHoxIqeU_H3_cDlkIVmAOYf0gVnV7g",
"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcRLtZHrzluGj-EZcosXVni-Zmflqe4Fu1jGFSMVQAAzsdnS_2MeXw",
"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTKiUjsY-piPSuTA3mHfXAd7Zsg04m3lTw1IA1zKkJqnwKACiStwg",
"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcROhycG7nOgvDzDOP2lBG37sk6wbHaYPbFX_pBx4FlbxtSM7Z2u",
"https://c2.staticflickr.com/6/5099/5513125478_89d1729e3c_b.jpg",
"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTybyiNsOZrASdwsbcyl5SDh8aZyJdfVCjEJphTKA4Yf43dAfdknw",
"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTI7n06M_AHBFBkSwh7SLnC5OjEE6j0uSz-3mr5u_s8QA5SWjkk",
"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQUGJXi8BNyMSTEJcQHYqdl_8ABHd_ucuS0qeze8demczkzGUHbtA",
"https://c3.staticflickr.com/7/6016/5984105136_7d5fa946b0_b.jpg",
"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTYPbn6L7Hw2_Lw01e5biRojnlFiviS566cqEuiY9H_7Y_Kr2VxeQ",
"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcS-b3zNErmvMlbun8iDHOC4cZ6QC0sBchBIx6PsfFov_JSsMa4l",
"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRGcl15mygqfmdcgCmPlxr00-a87LJvTuEWuFp2xg_XI82fhfC-WQ",
"https://c2.staticflickr.com/8/7251/6904099452_939e1ac5f2_b.jpg",
"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSmz_u5DklKmUN4zbHiWWuGz46g8avWA7ajMgoDdicB9JF3lmAA",
"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcR_lGkmwloEs9xZwJzzPZ7KlSp0oY5jTN-OtamC7rlEY8IhvGYO",
"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRuzn6Ke_rwtWvktu8NTnMw1q-RlnR3SKevN0ITO_q2mWsv9i0G"
};
private List<ChildItem> createChildItems(int firstItem, int lastItem) {
List<ChildItem> myDataset = new ArrayList<>();
for(int i=firstItem; i < lastItem; i++) {
//Log.d(TAG, "firstItem: "+firstItem+" i: "+i+" lastItem: "+lastItem);
myDataset.add(new ChildItem("Number "+i, urls[i]));
}
return myDataset;
}
private static int mAppWidth;
private List<ParentItem> mDataset;
private List<ChildItem> mChildDataset;
// Provide a reference to the views for each data item
// Complex data items may need more than one view per item, and
// you provide access to all the views for a data item in a view holder
public static class ViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView mTextView;
public ViewPager mViewPager;
public ViewHolder(View v, Context context) {
super(v);
mTextView = (TextView) v.findViewById(R.id.text_bottom);
mViewPager = (ViewPager) v.findViewById(R.id.view_pager);
int px = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 40, v.getResources().getDisplayMetrics());
mViewPager.getLayoutParams().height = (mAppWidth - px);
}
}
// Provide a suitable constructor (depends on the kind of dataset)
public VerticalAdapter(Context context, List<ParentItem> myDataset, int appWidth) {
mDataset = myDataset;
mContext = context;
mAppWidth = appWidth;
}
// Create new views (invoked by the layout manager)
@Override
public VerticalAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
// create a new view
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.vertical_view, parent, false);
// set the view's size, margins, paddings and layout parameters
ViewHolder vh = new ViewHolder(v, mContext);
return vh;
}
// Replace the contents of a view (invoked by the layout manager)
@Override
public void onBindViewHolder(final ViewHolder holder, int position) {
// - get element from your dataset at this position
// - replace the contents of the view with that element
holder.mTextView.setText(mDataset.get(position).getText());
mChildDataset = createChildItems(position*3,(position*3)+3);
ImagePagerAdapter adapter = new ImagePagerAdapter(mChildDataset);
holder.mViewPager.setAdapter(adapter);
}
// Return the size of your dataset (invoked by the layout manager)
@Override
public int getItemCount() {
return mDataset.size();
}
/**
* ImagePagerAdapter to display images
*/
private class ImagePagerAdapter extends PagerAdapter {
List<ChildItem> mData;
public ImagePagerAdapter(List<ChildItem> data) {
mData = data;
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
Context context = mContext;
ImageView mImageView = new ImageView(context);
mImageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
Picasso.with(context)
.load(mData.get(position).getUrl())
.placeholder(R.drawable.place_holder)
.error(R.drawable.place_holder_error)
.into(mImageView);
((ViewPager) container).addView(mImageView, 0);
return mImageView;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
((ViewPager) container).removeView((ImageView) object);
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view == ((ImageView) object);
}
@Override
public int getCount() {
return mData.size();
}
}
}
答案 0 :(得分：0)
您需要在主视图中保存每个适配器的状态。 所以试试吧。我只包含相关代码，因此更容易理解。
private final int[] childPos;
// Provide a suitable constructor (depends on the kind of dataset)
public VerticalAdapter(Context context, List<ParentItem> myDataset, int appWidth) {
...
// assuming myDataset is a fixed size after
// its passed in. else u need to implement a variable list
childPos = new int[mDataset.size()];
}
// Replace the contents of a view (invoked by the layout manager)
@Override
public void onBindViewHolder(final ViewHolder holder, int position) {
ViewPager pager = holder.mViewPager;
pager.setAdapter(adapter);
// in case your adapter count changes;
childPos[position] = childPos[position] < adapter.Count() ? childPos[position] : 0;
final int trackPos = childPos[position];
pager.setCurrentItem(holder.pos);
pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
trackPos = position;
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
}