I've been duelling with this problem for a good few hours now. I have a nested RecyclerView (i.e. a RecyclerView that encompasses an inner Recycler view). Both the parent and child recycler view's are dynamic. The problem I encounter is that I cannot find a way to correctly notify the child (inner) recycler view when a CRUD, in particular a delete, occurs. At first it works ok, but then I get all sorts of random errors from "You must be a direct descend view" or getAdapterPosition returning -1 or just simply incorrect positions. I think my implementation is pretty standard so I ask what is the correct way to notify the inner recycler view.
I am pretty close to returning to my former implementation which involved an array of fragments each containing a recycling view, but I question about the performance of such design. My code is as follows:
Parent RecyclerView
public class RecipeRecyclerAdapter extends RecyclerView.Adapter<RecipeRecyclerAdapter.ViewHolder>
{
public interface OnRecipeRecyclerListener
{
//--------------------------- Proxy methods for OnDishRecyclerListener -----------------
void renameDish(int DishPosition, int RecipePosition);
void deleteDish(int DishPosition, int RecipePosition);
//--------------------------- OnRecipeRecyclerListener methods ----------------------------
void deleteRecipe(int RecipePosition);
void renameRecipe(int RecipePosition);
}
//Recycler Pool and tools
private RecyclerView.RecycledViewPool viewPool = new RecyclerView.RecycledViewPool();
//Recycler Parameters
private ArrayList<Recipe> allRecipes;
private Context context;
//Listener
@Setter
private OnRecipeRecyclerListener onRecipeRecyclerListener;
public RecipeRecyclerAdapter(Context context, ArrayList<Recipe> allRecipes)
{
this.allRecipes = allRecipes;
this.context = context;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType)
{
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.card_Recipe, parent, false);
return new RecipeRecyclerAdapter.ViewHolder(view, onRecipeRecyclerListener, context);
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position)
{
Recipe Recipe = allRecipes.get(position);
holder.RecipeName.setText(Utils.colourFirstLetter(context, Recipe.getRecipeName(), R.color.progressFxBar));
holder.RecipeDate.setText(Utils.getDate(Recipe.getTimestamp()));
// Create layout manager with initial prefetch item count
LinearLayoutManager layoutManager = new LinearLayoutManager(
holder.DishsRecycler.getContext(),
LinearLayoutManager.VERTICAL,
false
);
layoutManager.setInitialPrefetchItemCount(Recipe.getDishs().size());
DishRecyclerAdapter DishsRecyclerAdapter = new DishRecyclerAdapter(Recipe.getDishs(), holder, context);
holder.DishsRecycler.setLayoutManager(layoutManager);
holder.DishsRecycler.setAdapter(DishsRecyclerAdapter);
holder.DishsRecycler.setRecycledViewPool(viewPool);
}
@Override
public int getItemCount()
{
return allRecipes.size();
}
static class ViewHolder extends RecyclerView.ViewHolder implements DishRecyclerAdapter.OnDishRecyclerListener
private OnRecipeRecyclerListener onRecipeRecyclerListener;
private Context context;
TextView RecipeName, RecipeDate;
ImageView addDish;
//The Dishs Recycler
RecyclerView DishsRecycler;
public ViewHolder(@NonNull View itemView, OnRecipeRecyclerListener onRecipeRecyclerListener, Context context)
{
super(itemView);
this.onRecipeRecyclerListener = onRecipeRecyclerListener;
this.context = context;
RecipeName = itemView.findViewById(R.id.RecipeName);
RecipeDate = itemView.findViewById(R.id.RecipeDate);
addDish = itemView.findViewById(R.id.addDish);
DishsRecycler = itemView.findViewById(R.id.DishsRecyclerView);
loadListeners(itemView);
}
private void loadListeners(@NonNull View initView)
{
RecipeName.setOnClickListener(v ->
{
PopupMenu popup = new PopupMenu(context, v);
MenuInflater inflater = popup.getMenuInflater();
inflater.inflate(R.menu.Recipe_floating_menu, popup.getMenu());
popup.show();
popup.setOnMenuItemClickListener(item ->
{
switch (item.getItemId())
{
case R.id.menuDeleteRecipe:
onRecipeRecyclerListener.deleteRecipe(getAdapterPosition());
return true;
case R.id.menuRenameRecipe:
onRecipeRecyclerListener.renameRecipe(getAdapterPosition());
return true;
case R.id.menuRecipeProps:
onRecipeRecyclerListener.RecipeProps(getAdapterPosition());
return true;
default:
return false;
}
});
});
addDish.setOnClickListener(v ->
{
onRecipeRecyclerListener.addDish(getAdapterPosition());
});
}
//******************************* OnDishRecyclerListener *******************************
@Override
public void renameDish(int position)
{
onRecipeRecyclerListener.renameDish(position, getAdapterPosition());
}
@Override
public void deleteDish(int position)
{
onRecipeRecyclerListener.deleteDish(position, getAdapterPosition());
}
}
}
Child (inner) RecyclerView
public class DishRecyclerAdapter extends RecyclerView.Adapter<DishRecyclerAdapter.ViewHolder>
{
public interface OnDishRecyclerListener
{
void renameDish(int position);
void deleteDish(int position);
}
private OnDishRecyclerListener onDishRecyclerListener;
private ArrayList<Dish> allDishs;
private Context context;
public DishRecyclerAdapter(ArrayList<Dish> allDishs, OnDishRecyclerListener onDishRecyclerListener, Context context)
{
this.onDishRecyclerListener = onDishRecyclerListener;
this.allDishs = allDishs;
this.context = context;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType)
{
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.card_Dishs, parent, false);
return new ViewHolder(context, view, onDishRecyclerListener);
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position)
{
Dish Dish = allDishs.get(position);
holder.DishName.setText(Dish.getDishName());
}
@Override
public int getItemCount()
{
return allDishs.size();
}
public class ViewHolder extends RecyclerView.ViewHolder
{
private Context context;
TextView DishName; //plus a bunch of other Views I just removed for the sake of simplicity
OnDishRecyclerListener onDishRecyclerListener;
public ViewHolder(Context context, @NonNull View itemView, OnDishRecyclerListener onDishRecyclerListener)
{
super(itemView);
this.context = context;
DishName = itemView.findViewById(R.id.DishName);
this.onDishRecyclerListener = onDishRecyclerListener;
loadListeners(itemView);
}
private void loadListeners(@NonNull View v)
{
//Rename an Dish
DishName.setOnClickListener(view ->
{
PopupMenu popup = new PopupMenu(context, v);
MenuInflater inflater = popup.getMenuInflater();
inflater.inflate(R.menu.Dish_floating_menu, popup.getMenu());
popup.show();
popup.setOnMenuItemClickListener(item ->
{
switch (item.getItemId())
{
case R.id.menuDeleteDish:
onDishRecyclerListener.deleteDish(getAdapterPosition());
return true;
case R.id.menuRenameDish:
onDishRecyclerListener.renameDish(getAdapterPosition());
return true;
case R.id.menuDishProps:
return true;
default:
return false;
}
});
});
}
}
}
An extraction of the fragment calling the parent recycler view:
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.fragment_Recipe_panel, container, false);
recyclerRecipe = view.findViewById(R.id.RecipeRecyclerView);
SimpleItemAnimator simpleItemAnimator = (SimpleItemAnimator) recyclerRecipe.getItemAnimator();
if(simpleItemAnimator !=null)
{
simpleItemAnimator.setSupportsChangeAnimations(true);
}
RecipeAdapter = new RecipeRecyclerAdapter(getContext(), allRecipes);
RecipeAdapter.setOnRecipeRecyclerListener(this);
//recyclerRecipe.setHasFixedSize(true);
recyclerRecipe.setLayoutManager(new LinearLayoutManager(getContext()));
recyclerRecipe.setAdapter(RecipeAdapter);
return view;
}
public void createRecipe(String RecipeName)
{
Recipe Recipe = new Recipe(RecipeName, getContext());
allRecipes.add(0,Recipe);
RecipeAdapter.notifyItemInserted(0);
}
@Override
public void deleteRecipe(int RecipePosition)
{
allRecipes.remove(RecipePosition);
RecipeAdapter.notifyItemRemoved(RecipePosition);
}
@Override
public void addDish(int RecipePosition)
{
allRecipes.get(RecipePosition).getDishs().add(new Dish(DishName));
RecipeAdapter.notifyItemChanged(RecipePosition);
}
@Override
public void deleteDish(int DishPosition, int RecipePosition)
{
Recipe Recipe = allRecipes.get(RecipePosition);
Dish Dish = Recipe.getDishs().get(DishPosition);
Dish.getTimer().destroyTimer();
Recipe.getDishs().remove(DishPosition);
RecipeAdapter.notifyItemChanged(RecipePosition);
}
I figured out what the problem was (after LOADS OF HOURS). I needed to notify first the parent recycler and then the child recycler in that order.
//adding an item to the inner list
recipeAdapter.notifyItemChanged(recipePosition);
dishsRecycler.getAdapter().notifyItemInserted(recipe.getDishs().size()-1);
//deleting an inner list item
recipeAdapter.notifyItemChanged(recipePosition);
dishsRecycler.getAdapter().notifyItemRemoved()
However the biggest culprit was having a common recyclerPool for all the inner recyclerviews, so removed this line from the code
//REMOVED THESE LINES
private RecyclerView.RecycledViewPool viewPool = new RecyclerView.RecycledViewPool();
holder.DishsRecycler.setRecycledViewPool(viewPool);
Also, I refrained from using notifyDataSet() as that for some reason throws NO_POSITION (-1).