I am using a view pager with three tabs (three fragments). In one of these fragments I have a recycler view. The items in this recycler view get updated every 2 seconds from the web. When I first start up the app, the recycler view runs just fine. Even when navigating to different tabs or navigating out of my app with home button, it all works.
However when I close the app by using the backkey and then go into my app again, the recycler view is not updating anymore. It shows the status that it had when the app quit. I monitor the adapter via the console and it keeps on working with the correct data, only the recycler view doesn't show this. I tried all kinds of stuff to "reconnect" adapter and recycler view but it won't work. I am having this issue for days. Any idea for the cause of this problem? See the relevant code for troubleshooting. Thank you!
public class UserAreaFragment extends Fragment implements PopupMenu.OnMenuItemClickListener {
private RecyclerView mRecyclerview;
private UserAdapter mAdapter;
private RecyclerView.LayoutManager mLayoutmanager;
private Handler mainHandler = new Handler();
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.fragment_user_area, container, false);
...
mAdapter = new UserAdapter(getActivity(), UserDataSingleton.getUserList());
mRecyclerview = root.findViewById(R.id.userListing);
mRecyclerview.setLayoutManager(new LinearLayoutManager(getActivity()));
mRecyclerview.setAdapter(mAdapter);
mAdapter.setOnItemClickListener(new UserAdapter.OnItemClickListener() {
@Override
public void onItemClick(int position) {
...
}
});
}
//Somewhere in my method that receives the data from an online DB:
UserDataSingleton.getUserList().clear();
UserDataSingleton.getUserList().addAll(serverResponse);
mainHandler.post(updateUi);
//And finally the updateUi method: this is essential just sorting and then notifydatasetchanged
Runnable updateUi = new Runnable() {
@Override
public void run() {
Collections.sort(UserDataSingleton.getUserList(), new Comparator<UserItem>() {
@Override
public int compare(UserItem lhs, UserItem rhs) {
// -1 - less than, 1 - greater than, 0 - equal, all inversed for descending
return Double.parseDouble(lhs.getmDistance()) > Double.parseDouble(rhs.getmDistance()) ? 1 : Double.parseDouble(lhs.getmDistance()) < Double.parseDouble(rhs.getmDistance()) ? -1 : 0;
}
});
mAdapter.notifyDataSetChanged();
}
};
//and this is my Adapter:
public class UserAdapter extends RecyclerView.Adapter<UserAdapter.UserViewHolder> {
private UserAdapter.OnItemClickListener mListener;
private Context mContext;
private List<UserItem> mUserlist;
public UserAdapter(Context context,List<UserItem> userList){
mUserlist=userList;
mContext = context;
}
public interface OnItemClickListener{
void onItemClick(int position);
}
public void setOnItemClickListener(UserAdapter.OnItemClickListener listener) {
this.mListener = listener;
}
public static class UserViewHolder extends RecyclerView.ViewHolder{
public TextView mUsername;
public TextView mDistance;
public ImageView userIcon;
public UserViewHolder(@NonNull View itemView, final UserAdapter.OnItemClickListener listener) {
super(itemView);
mUsername = itemView.findViewById(R.id.tvNearUsername);
mDistance = itemView.findViewById(R.id.tvDistance);
userIcon = itemView.findViewById(R.id.usericon);
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (listener != null){
int position = getAdapterPosition();
if (position!= RecyclerView.NO_POSITION){
listener.onItemClick(position);
}
}
}
});
}
}
@NonNull
@Override
public UserAdapter.UserViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(mContext);
View v= inflater.inflate(R.layout.user_item, parent, false);
UserViewHolder uvh= new UserViewHolder(v,mListener);
return uvh;
}
@Override
public void onBindViewHolder(@NonNull UserAdapter.UserViewHolder holder, int position) {
UserItem currentitem = mUserlist.get(position);
holder.mUsername.setText(currentitem.getmNearUsername());
if (currentitem.isArea()){
holder.mDistance.setVisibility(View.INVISIBLE);
holder.userIcon.setImageResource(R.drawable.ic_placeicon);
}else{
holder.mDistance.setVisibility(View.VISIBLE);
}
int distToNextTen = ((Integer.parseInt(currentitem.getmDistance())+5)/10)*10+10;
holder.mDistance.setText("< "+distToNextTen+"m");
}
@Override
public int getItemCount() {
return mUserlist.size();
}
}
I tried to only display the lines that affect the issue for better readability. If you need to see more code just let me know. Thankful for this great community!
(I think problem might be in connection with the main Handler not pointing to the correct view or maybe an issue with adapter-recyclerview connection but I can't find a solution tried so many things already)
