java - E/RecyclerView : No adapter attached; skipping layout when using searchview

Question

这个问题已经有答案了:

recyclerview No adapter attached; skipping layout (38 个回答)

已关闭 3 年前。

适配器类

当前正在尝试实现对我的回收器 View 的搜索。当我尝试运行搜索时，出现“E/RecyclerView:未连接适配器；跳过布局”的错误。我尝试过使用notifyDatasetChanged()但仍然不起作用。当我打印过滤列表时，我可以看到它包含应返回的正确数量的项目，但它没有被更新。谢谢

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> implements Filterable {

        Context context;
         ArrayList<New> fullList;
        ArrayList<New> list;

        public RecyclerViewAdapter(Context context, ArrayList<New> fullList) {
            this.fullList = fullList;
            this.list  = new ArrayList<>(fullList);
            this.context = context;
        }

        @Override
        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.rows, parent, false);
            ViewHolder viewHolder = new ViewHolder(view);
            return viewHolder;
        }

        @Override
        public void onBindViewHolder(ViewHolder holder, int position) {

            New studentDetails = fullList.get(position);
            holder.setTitle(studentDetails.getType().toString());

        }
        @Override
        public int getItemCount() {

            return fullList.size();
        }

        @Override
        public Filter getFilter() {
            return exampleFilter;
        }

        private Filter exampleFilter = new Filter() {
            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                List<New> filteredList = new ArrayList<>();
                if(constraint == null || constraint.length()==0)
                {
                    filteredList.addAll(list);
                }
                else
                {
                    String filterPattern = constraint.toString().toLowerCase().trim();

                    for(New item: fullList)
                    {
                        if(item.getType().toString().toLowerCase().contains(filterPattern))
                        {
                            filteredList.add(item);
                        }
                    }
                }
                FilterResults results= new FilterResults();
                results.values = filteredList;
                System.out.println("filtered " + filteredList.toString());
                return results;
            }

            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {

                list.clear();
                list.addAll((List)results.values);
                notifyDataSetChanged();
            }
        };

fragment

@Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        super.onCreateOptionsMenu(menu, inflater);
        // Do something that differs the Activity's menu here
        MenuItem searchItem = menu.findItem(R.id.search);
        SearchView searchView = (SearchView)searchItem.getActionView();
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }
            @Override
            public boolean onQueryTextChange(String newText) {
                System.out.println("before" + list);
                adapter.getFilter().filter(newText);
                System.out.println("after" + list);
                return false;
            }

        });

    }
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        mView= inflater.inflate(R.layout.fragment_shown,container,false);
        myRecycler=(RecyclerView)mView.findViewById(R.id.recycler);
        myRecycler.setHasFixedSize(true);
        myRecycler.setLayoutManager(new LinearLayoutManager(getContext()));
        mDatabase = FirebaseDatabase.getInstance().getReference().child("Student");

        mDatabase.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot snapshot) {
                for (DataSnapshot dataSnapshot : snapshot.getChildren()) {
                    New studentDetails = dataSnapshot.getValue(New.class);
                    Map<String, String> map = (Map) dataSnapshot.getValue();
                    String message = map.get("name");
                    if(message.equals("studentname"))
                    {
                        list.add(studentDetails);
                    }

                }

                adapter = new RecyclerViewAdapter(getActivity(), list);
                myRecycler.setAdapter(adapter);
                adapter.notifyDataSetChanged();

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {



            }
        });

        return mView;
    }

Answer 1

问题是，在从数据库获取更新之前，您不会创建适配器。您应该在监听器之外设置适配器，并根据需要更新它:

 public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    mView= inflater.inflate(R.layout.fragment_shown,container,false);
    myRecycler=(RecyclerView)mView.findViewById(R.id.recycler);
    myRecycler.setHasFixedSize(true);
    myRecycler.setLayoutManager(new LinearLayoutManager(getContext()));

 //set your adapter when you create the view
 adapter = new RecyclerViewAdapter(getActivity(), list);
                myRecycler.setAdapter(adapter);
    mDatabase = FirebaseDatabase.getInstance().getReference().child("Student");

    mDatabase.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            for (DataSnapshot dataSnapshot : snapshot.getChildren()) {
                New studentDetails = dataSnapshot.getValue(New.class);
                Map<String, String> map = (Map) dataSnapshot.getValue();
                String message = map.get("name");
                if(message.equals("studentname"))
                {
                    list.add(studentDetails);
                }

            }


            adapter.notifyDataSetChanged();

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {



        }
    });

    return mView;
}

您还需要更新您的数据集。您可以在适配器类中执行类似的操作:

public void updateData(List<New> myData){
     list = myData; 
     notifyDataSetChanged()
}

然后，您不调用 adapter.notifyDataSetChanged()，而是调用 adapter.updateData(list)。