java - 将数据从 RecyclerView.Adapter 传递到 fragment onClick

Question

我试图弄清楚如何将数据从 RecyclerView 中单击的项目获取到 Fragment 中的 ListView 。我似乎不知道如何做到这一点，因为我无法让我的 bundle 工作。

我尝试过 Stackoverflow 上提供的各种解决方案，但没有一个有效。我已设法从 recyclerview 获取信息，但我一直在试图弄清楚如何将其传递给 fragment 。有人可以帮我吗？

适配器类:

public class FoodAdapter extends RecyclerView.Adapter<FoodAdapter.ViewHolder> {

    private Context context;

    ArrayList<FoodActivity> list;
    public FoodAdapter(ArrayList<FoodActivity> list){
        this.list = list;
    }


    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.listview_item_food, parent, false);

        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull final ViewHolder holder, final int position) {
        holder.foods.setText(list.get(position).getName());
        holder.carbo.setText(list.get(position).getCarbohydrates());
        holder.protein.setText(list.get(position).getProtein());
        holder.fats.setText(list.get(position).getFats());

        //Get items from recyclerview when user clicks them. Then send them to FoodFragment
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                String foods = list.get(position).getName();
                String carbo = list.get(position).getCarbohydrates();
                String protein = list.get(position).getProtein();
                String fats = list.get(position).getFats();

                Toast.makeText(v.getContext(), "test: " + foods, Toast.LENGTH_SHORT).show();


            }
        });
    }


    @Override
    public int getItemCount() {
        return list.size();
    }

    class ViewHolder extends RecyclerView.ViewHolder {
        TextView foods, carbo, fats, protein;

        public ViewHolder(View itemView) {
            super(itemView);

            carbo = itemView.findViewById(R.id.carbo);
            protein = itemView.findViewById(R.id.protein);
            fats = itemView.findViewById(R.id.fats);
            foods = itemView.findViewById(R.id.food);
        }
    }
}

数据来源的 fragment :

public class TrackingFragment extends Fragment {

    DatabaseReference databaseReference;
    ArrayList<FoodActivity> list;
    RecyclerView recyclerView;
    SearchView searchView;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_tracking, container, false);

        databaseReference = FirebaseDatabase.getInstance().getReference().child("foods");
        recyclerView = view.findViewById(R.id.rv);
        searchView = view.findViewById(R.id.searchFood);

        return view;
    }

    @Override
    public void onStart() {
        super.onStart();

        if(databaseReference != null){
            databaseReference.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                    if(dataSnapshot.exists()){
                        list = new ArrayList<>();
                        for(DataSnapshot ds : dataSnapshot.getChildren()){
                            list.add(ds.getValue(FoodActivity.class));
                        }
                        FoodAdapter adapter = new FoodAdapter(list);
                        recyclerView.setAdapter(adapter);


                    }
                }

                @Override
                public void onCancelled(@NonNull DatabaseError databaseError) {
                    Toast.makeText(getActivity(), databaseError.getMessage(), Toast.LENGTH_SHORT).show();
                }
            });
        }
        if(searchView != null){
            searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
                @Override
                public boolean onQueryTextSubmit(String query) {
                    return false;
                }

                @Override
                public boolean onQueryTextChange(String newText) {
                    search(newText);
                    return true;
                }
            });
        }
    }

    private void search(String str){
        ArrayList<FoodActivity> searchList = new ArrayList<>();
        for(FoodActivity object : list){
            if(object.getName().toLowerCase().contains(str.toLowerCase())){
                searchList.add(object);
            }
        }
        FoodAdapter foodAdapter = new FoodAdapter(searchList);
        recyclerView.setAdapter(foodAdapter);
    }

}

以及它需要去的类:

public class FoodFragment extends Fragment {

    ImageButton addFood;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_food, container, false);

        addFood = view.findViewById(R.id.addFood);

        addFood.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                FragmentTransaction fr = getFragmentManager().beginTransaction();
                fr.replace(R.id.fragment_container, new TrackingFragment());
                fr.addToBackStack(null).commit();
            }
        });

        return view;
    }

}

Answer 1

最简单的方法是向 Activity 添加所需的变量，使用 onClick() 设置它们的值，然后检索其他 fragment 中的数据:

• Activity 中:

  String foods;
  
  public String getFoods() {
      return foods;
  }
  
  public void setFoods(String foods) {
      this.foods = foods;
  }
  

• 在适配器中:

     holder.itemView.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
             ((YourActivity)getActivity()).setFoods("Any value");
          }
      });
  

• 在目标 fragment 中:

  字符串食物 = ((YourActivity)getActivity()).getFoods();