notifyItemRangeRemoved和notifyItemRangeInserted

时间：2019-05-27 12:37:11

标签： android android-recyclerview recycler-adapter notifydatasetchanged notifyitemrangeremoved

我已经创建了可扩展的recylerview，下面是我的适配器代码

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

    List<Object> objects;
    FoodMenuParentListener foodMenuParentListener;
    boolean isAddAllowed;

    boolean isVegOnly;
    static final int TYPE_FOOD = 0;
    static final int TYPE_MENU_ITEM = 1;


    public FoodMenuRecyclerAdapter(List<Object> objects, FoodMenuParentListener foodMenuParentListener, boolean isVegOnly, boolean isAddAllowed) {
        this.foodMenuParentListener = foodMenuParentListener;
        this.isVegOnly = isVegOnly;
        this.isAddAllowed = isAddAllowed;
        this.objects = objects;
    }

    @Override
    public int getItemViewType(int position) {
        Object object = objects.get(position);
        if (object instanceof FoodMenuItem) {
            return TYPE_FOOD;
        } else if(this.objects.get(position) == null) {
            throw new IllegalStateException("Null object added");
        }else {
            return TYPE_MENU_ITEM;
        }
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View view;
        switch (getItemViewType(i)) {
            case TYPE_FOOD:
                view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.layout_food_parent, viewGroup, false);
                return new MenuViewHolder(view);
            case TYPE_MENU_ITEM:
                view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.layout_food_child, viewGroup, false);
                return new ChildMenuHolder(view);
            default:
                throw new IllegalArgumentException("Invalid viewType");

        }
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, int i) {
        Object object = objects.get(i);
        Context context = viewHolder.itemView.getContext();
        Log.d("myAdapter","position"+ i + ":"+ ((getItemViewType(i) == TYPE_MENU_ITEM) ? "TYPE_MENU_ITEM" : "TYPE_FOOD"));
         if (getItemViewType(i) == TYPE_MENU_ITEM) {
            ChildMenuHolder childMenuHolder = (ChildMenuHolder) viewHolder;
            GmrApplication gmrApplication = (GmrApplication) context.getApplicationContext();
            Item item = (Item) object;
            childMenuHolder.tvPrice.setText(gmrApplication.getCurrencySymbolString() + item.getPrice());
            childMenuHolder.tvTitle.setText(item.getTitle());
            childMenuHolder.txtQty.setText(String.valueOf(item.getQuatity()));
            childMenuHolder.txtCartInc.setVisibility(item.isAddedToCart() ? View.VISIBLE : View.GONE);
            childMenuHolder.txtQty.setVisibility(item.isAddedToCart() ? View.VISIBLE : View.GONE);
            childMenuHolder.txtCartDec.setVisibility(item.isAddedToCart() ? View.VISIBLE : View.GONE);
            childMenuHolder.btnAdd.setVisibility(!item.isAddedToCart() ? View.VISIBLE : View.GONE);
            childMenuHolder.btnAdd.setBackgroundResource(isAddAllowed ? R.drawable.rounded_bottom_edge_shape_food : R.drawable.rounded_bottom_edge_shape_disable);
            childMenuHolder.btnAdd.setTextColor(isAddAllowed ? ContextCompat.getColor(context, R.color.button_green) : ContextCompat.getColor(context, R.color.gray_a1));
            childMenuHolder.ivType.setColorFilter(item.getType().equalsIgnoreCase(Item.FOOD_TYPE_VEG) ? ContextCompat.getColor(context, R.color.selected_green) : ContextCompat.getColor(context, R.color.app_red));
        } else {
            FoodMenuItem foodMenuItem = (FoodMenuItem) object;
            MenuViewHolder menuViewHolder = (MenuViewHolder) viewHolder;
            if (isVegOnly) {
                List<Item> items = new ArrayList<>();
                for (Item item : foodMenuItem.getItems()) {
                    if (item.getType().equalsIgnoreCase(Item.FOOD_TYPE_VEG)) {
                        items.add(item);
                    }
                }
                menuViewHolder.tvNumItems.setText("(" + items.size() + " items)");

            } else {
                menuViewHolder.tvNumItems.setText("(" + foodMenuItem.getItems().size() + " items)");

            }
            menuViewHolder.ivArrow.setImageResource(foodMenuItem.isExpanded() ? R.drawable.chev_up : R.drawable.chev_down);
            menuViewHolder.tvTitle.setText(foodMenuItem.getCategoryName());
        }


    }


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

    public class MenuViewHolder extends RecyclerView.ViewHolder {
        TextView tvTitle;
        TextView tvNumItems;
        ImageView ivArrow;
        // RecyclerView rvMenu;
        View rlArrow;

        public MenuViewHolder(@NonNull View itemView) {
            super(itemView);
            tvTitle = (TextView) itemView.findViewById(R.id.tvTitle);
            tvNumItems = (TextView) itemView.findViewById(R.id.tvNumItems);
            ivArrow = (ImageView) itemView.findViewById(R.id.ivArrow);
            // rvMenu.setNestedScrollingEnabled(false);
            rlArrow = itemView.findViewById(R.id.rlArrow);
            rlArrow.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    if (foodMenuParentListener != null) {
                        Object object = objects.get(getAdapterPosition());
                        if (object instanceof FoodMenuItem) {
                            FoodMenuItem foodMenuItem = (FoodMenuItem) object;
                            foodMenuParentListener.OnExpandClick(foodMenuItem, getAdapterPosition());

                        }
                    }
                }
            });
            tvTitle.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    if (foodMenuParentListener != null) {
                        Object object = objects.get(getAdapterPosition());
                        if (object instanceof FoodMenuItem) {
                            FoodMenuItem foodMenuItem = (FoodMenuItem) object;
                            foodMenuParentListener.OnExpandClick(foodMenuItem, getAdapterPosition());

                        }
                    }
                }
            });
        }
    }

    public boolean isVegOnly() {
        return isVegOnly;
    }

    public void setVegOnly(boolean vegOnly) {
        isVegOnly = vegOnly;
    }

    public interface FoodMenuParentListener extends AddItemListener {
        public void OnExpandClick(FoodMenuItem foodMenuItem, int position);

        public void OnVegOnlyClicked();
    }

    public class ChildMenuHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        ImageView ivType;
        TextView tvTitle;
        TextView tvPrice;
        TextView txtCartDec;
        TextView txtQty;
        TextView txtCartInc;

        Button btnAdd;

        public ChildMenuHolder(@NonNull View itemView) {
            super(itemView);
            ivType = (ImageView) itemView.findViewById(R.id.ivType);
            tvTitle = (TextView) itemView.findViewById(R.id.tvTitle);
            tvPrice = (TextView) itemView.findViewById(R.id.tvPrice);
            txtCartDec = (TextView) itemView.findViewById(R.id.txtCartDec);
            txtQty = (TextView) itemView.findViewById(R.id.txtQty);
            txtCartInc = (TextView) itemView.findViewById(R.id.txtCartInc);
            btnAdd = (Button) itemView.findViewById(R.id.btnAdd);
            btnAdd.setOnClickListener(this);
            txtCartInc.setOnClickListener(this);
            txtCartDec.setOnClickListener(this);
        }

        @Override
        public void onClick(View view) {

        }
    }

    public void setExpandIndex(int expandIndex) {
    }

    public boolean isItemExpanded(int position) {
        return true;
    }


    public class VegOnlyViewHolder extends RecyclerView.ViewHolder {
        Switch wtVeg;

        public VegOnlyViewHolder(@NonNull View itemView) {
            super(itemView);
            wtVeg = (Switch) itemView.findViewById(R.id.wtVeg);
            wtVeg.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
                    if (foodMenuParentListener != null) {
                        foodMenuParentListener.OnVegOnlyClicked();
                    }
                }
            });
        }
    }


    public interface AddItemListener {
        public void onAddClicked(Item item, int parentIndex);

        public void increaseItemCount(Item item, int parentIndex);

        public void decreaseItemCount(Item item, int parentIndex);
    }

    public void addAll(int position, List<Item> objectsToAdd) {
        this.objects.addAll(position, objectsToAdd);
    }

    public void addItem(int position, Item object) {
        this.objects.add(position, object);
    }
    public void removeItem(Object object) {
        this.objects.remove(object);
    }


    public void removeAll(List<Item> objectsToRemove) {
        objects.removeAll(objectsToRemove);
        Log.d("myAdapter","item at first position after remove" + ":"+objects.get(0));
        Log.d("myAdapter","item at second position after remove" + ":"+objects.get(1));
    }

    public Object isItemInList(Item item) {
        for (Object object : objects) {
            if (object instanceof Item && ((Item) object).getId().equals(item.getId())) {
                return object;
            }
        }
        return null;
    }
    }

以下是我的Fragment中的代码，用于展开折叠RecyclerView 

 @Override
        public void OnExpandClick(FoodMenuItem foodMenuItem, int position) {
            if (recyclerViewMenu != null && recyclerViewMenu.getAdapter() != null) {
                recyclerViewMenu.getRecycledViewPool().clear();
                FoodMenuRecyclerAdapter foodMenuRecyclerAdapter = (FoodMenuRecyclerAdapter) recyclerViewMenu.getAdapter();
                foodMenuItem.setExpanded(!foodMenuItem.isExpanded());
                if (foodMenuItem.isExpanded()) {
                    foodMenuRecyclerAdapter.addAll(position + 1, foodMenuItem.getItems());
                    foodMenuRecyclerAdapter.notifyItemRangeInserted(position, foodMenuItem.getItems().size());

                } else {
                    foodMenuRecyclerAdapter.removeAll(foodMenuItem.getItems());
                    foodMenuRecyclerAdapter.notifyItemRangeRemoved(position + 1, foodMenuItem.getItems().size());

                }

            }

        }

以下是片段中用于扩展和折叠的侦听器代码

public void OnExpandClick(FoodMenuItem foodMenuItem, int position) {
            if (recyclerViewMenu != null && recyclerViewMenu.getAdapter() != null) {
                FoodMenuRecyclerAdapter foodMenuRecyclerAdapter = (FoodMenuRecyclerAdapter) recyclerViewMenu.getAdapter();
                foodMenuItem.setExpanded(!foodMenuItem.isExpanded());
                if (foodMenuItem.isExpanded()) {
                    foodMenuRecyclerAdapter.addAll(position + 1, foodMenuItem.getItems());
                    foodMenuRecyclerAdapter.notifyItemRangeInserted(position, foodMenuItem.getItems().size());

                } else {
                    foodMenuRecyclerAdapter.removeAll(foodMenuItem.getItems());
                    foodMenuRecyclerAdapter.notifyItemRangeRemoved(position +1 , foodMenuItem.getItems().size());

                }

            }

        }

上面的代码在引发异常堆栈跟踪之后引发异常

 java.lang.ClassCastException: com.myapp.android.pojoentities.Item cannot be cast to com.myapp.android.pojoentities.FoodMenuItem
    at com.myapp.android.food.menu.FoodMenuRecyclerAdapter.onBindViewHolder(FoodMenuRecyclerAdapter.java:104)
    at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6781)
    at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6823)
    at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5752)
    at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6019)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5858)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5854)
    at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
    at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
    at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
    at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:612)
    at android.support.v7.widget.RecyclerView.dispatchLayoutStep1(RecyclerView.java:3875)
    at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3639)
    at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:4194)
    at android.view.View.layout(View.java:16636)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
    at android.view.View.layout(View.java:16636)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
    at android.view.View.layout(View.java:16636)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.support.design.widget.CoordinatorLayout.layoutChild(CoordinatorLayout.java:1183)
    at android.support.design.widget.CoordinatorLayout.onLayoutChild(CoordinatorLayout.java:870)
    at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:889)
    at android.view.View.layout(View.java:16636)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
    at com.myapp.android.custom.FitsSystemWindowsFrameLayout.onLayout(FitsSystemWindowsFrameLayout.java:247)
    at android.view.View.layout(View.java:16636)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1231)
    at android.view.View.layout(View.java:16636)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
    at android.view.View.layout(View.java:16636)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
    at android.view.View.layout(View.java:16636)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
    at android.view.View.layout(View.java:16636)
    at android.view.ViewGroup.layout(ViewGroup.java:5437)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
    at android.view.View.layout(View.java:

更新：

折叠第一个项目后，我检查了列表中前两个项目的日志记录，发现前两个项目的类型为ParentItem，即FoodMenuItem，但是当我检查相同位置的getItemViewType日志时，它以某种方式返回了错误的值

以下是日志

05-28 00:13:47.643 32010-32010/com.myapp.android D/myAdapter: item at first position after remove:com.myapp.android.pojoentities.FoodMenuItem@7fdf002
05-28 00:13:47.643 32010-32010/com.myapp.android D/myAdapter: item at second position after remove:com.myapp.android.pojoentities.FoodMenuItem@9cbfd13
05-28 00:13:47.664 32010-32010/com.myapp.android D/myAdapter: position1:TYPE_FOOD
05-28 00:13:47.678 32010-32010/com.myapp.android D/myAdapter: position2:TYPE_MENU_ITEM

4 个答案:

答案 0 :(得分：0)

您获得了一个模型foodmenu对象，然后在onBindView上直接将该对象更改为items。这就是为什么您会收到此错误。

答案 1 :(得分：0)

这并非直接解决所提问题，但结果与安全的代码流相同

步骤：

  1. 您可以创建列表List<MyDataType> myList = new ArrayList<>();来存储或更改要显示的数据。

  2. 现在，如果您希望将recyclerView保留为空白，请清除列表，然后创建一个新的Adapter Class对象，并使用新的适配器对象设置recylerView

myList.clear() MyRecAdapter newEmptyRecAdapter = new MyRecAdapter(myList); recyclerView.setAdapter(newEmptyRecAdapter);

  1. 再次从模型或POJO或存储或提取数据的位置填充列表，并创建一个新的recyclerView对象并重置为适配器

myList = myModelClass.getList(); MyRecAdapter newFullRecAdapter = new MyRecAdapter(myEmptyList); recyclerView.setAdapter(newFullRecAdapter);

已更新

根据评论：

  

不能解决我的问题，在展开和折叠查找时出现问题   围绕它回答

步骤：

  1. 制作模型或POJO并直接从该Model / POJO中获取Recyler数据

  2. 使用0个数据填充清除Model / POJO

  3. 运行recyclerView.notifyDatasetChanged()，这将自动折叠recyclerView

  4. 提供一个时间间隔，然后重新填充Model / POJO并调用recyclerView.notifyDatasetChanged()

答案 2 :(得分：0)

onCreateViewHolder中的整数参数是viewType，而不是位置：see here

  

公共抽象VH onCreateViewHolder（ViewGroup父级，int viewType）；

因此，无需致电getItemViewType(i)。

我希望这能解决您的问题。

答案 3 :(得分：0)

FoodMenuRecyclerAdapter的onBindViewHolder方法错误

Item item = (Item) object;

将对象投射到FoodMenuItem。

FoodMenuItem item = (FoodMenuItem) object;
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