我试图弄清楚如何从RecyclerView中的单击项目中获取数据到片段中的列表视图。我似乎无法弄清楚如何做到这一点，因为我无法让我的捆绑工作。
我已经尝试过在Stackoverflow上提供的各种解决方案，但它们都没有奏效。我已经设法从recyclerview获取信息，但我不知道如何弄清楚如何将它传递给片段。有人可以帮帮我吗？
Adapter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);
}
}
}
数据来自的片段：
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);
}
}
还有它需要去的班级：
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;
}
}
要从FoodAdapter获取数据到TrackingFragment，您可以将TrackingFragment（或它实现的接口，理想情况下）作为参数添加到FoodAdapter构造函数中，然后使用该实例将ViewHolder点击转发到TrackingFragment进行处理。
要将数据从TrackingFragment获取到FoodFragment，请使用setTargetFragment / onActivityResult模式进行片段< - >片段通信。这个答案有一个例子：https://stackoverflow.com/a/13733914/3238938
最简单的方法是添加活动所需的变量，使用onClick（）设置其值，然后检索其他片段中的数据：
String foods;
public String getFoods() {
return foods;
}
public void setFoods(String foods) {
this.foods = foods;
}
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
((YourActivity)getActivity()).setFoods("Any value");
}
});
String foods = ((YourActivity)getActivity()).getFoods();按如下方式向适配器添加接口
public class FoodAdapter extends RecyclerView.Adapter<FoodAdapter.ViewHolder> {
interface OnClickListener {
void onClick(FoodActivity clickedItem);
}
private OnClickListener mCallback;
private ArrayList<FoodActivity> list;
public FoodAdapter(ArrayList<FoodActivity> list){
this.list = list;
}
public void setOnClickListener(OnClickListener callback) {
mCallback = callback;
}
@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) {
if (mCallback != null)
mCallback.onClick(list.get(position));
}
});
}
@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);
}
}
}