java - 无法解析 java.lang.ClassCastException

Question

我正在尝试开发我的第一个 Android 应用程序，但遇到以下错误 - 'java.lang.ClassCastException。这是我的java代码:

package com.example.fresh24;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class CartAdapter extends RecyclerView.Adapter {

    private List<CartItemModel> cartItemModelList;

    public CartAdapter(List<CartItemModel> cartItemModelList) {
        this.cartItemModelList = cartItemModelList;
    }

    @Override
    public int getItemViewType(int position) {
        switch (cartItemModelList.get(position).getType()) {
            case 0:
                return CartItemModel.CART_ITEM;
            case 1:
                return CartItemModel.TOTAL_AMOUNT;
            default:
                return -1;
        }
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
        switch (viewType) {
            case CartItemModel.CART_ITEM:
                View cartItemView = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.cart_item_layout, viewGroup, false);
                return new CartItemViewHolder(cartItemView);
            case CartItemModel.TOTAL_AMOUNT:
                View cartTotalView = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.cart_total_amount_layout, viewGroup, false);
                return new CartItemViewHolder(cartTotalView);
            default:
                return null;
        }
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, int position) {
        switch (cartItemModelList.get(position).getType()) {
            case CartItemModel.CART_ITEM:
                int resource = cartItemModelList.get(position).getProductImage();
                String title = cartItemModelList.get(position).getProducTitle();
                int freeCoupons = cartItemModelList.get(position).getFreeCoupons();
                String productPrice = cartItemModelList.get(position).getProductPrice();
                String cutPrice = cartItemModelList.get(position).getCutPrice();
                int offersApplied = cartItemModelList.get(position).getOffersApplied();
                ((CartItemViewHolder)viewHolder).setItemDetails(resource,title,freeCoupons,productPrice,cutPrice,offersApplied);
                break;
            case CartItemModel.TOTAL_AMOUNT:
                String totalItems = cartItemModelList.get(position).getTotalItems();
                String totalItemsPrice = cartItemModelList.get(position).getTotalItemPrice();
                String conveniencePrice = cartItemModelList.get(position).getConveniencePrice();
                String totalAmount = cartItemModelList.get(position).getTotalAmount();
                String savedAmount = cartItemModelList.get(position).getSavedAmount();
                ((CartTotalAmountViewHolder)viewHolder).setTotalAmount(totalItems,totalItemsPrice,conveniencePrice,totalAmount,savedAmount);
                break;
            default:
                return;
        }
    }

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

    class CartItemViewHolder extends RecyclerView.ViewHolder {
        private ImageView productImage;
        private ImageView freecouponIcon;
        private TextView productTitle;
        private TextView freeCoupons;
        private TextView productPrice;
        private TextView productCutPrice;
        private TextView offersApplied;
        /*private TextView couponsApplied;
        private TextView productQuantity;*/

        public CartItemViewHolder(@NonNull View itemView) {
            super(itemView);
            productImage = itemView.findViewById(R.id.product_image);
            productTitle = itemView.findViewById(R.id.product_title);
            freecouponIcon = itemView.findViewById(R.id.free_coupon_icon);
            freeCoupons = itemView.findViewById(R.id.tv_free_coupon);
            productPrice = itemView.findViewById(R.id.product_price);
            productCutPrice = itemView.findViewById(R.id.cut_price);
            offersApplied = itemView.findViewById(R.id.offers_applied);

        }

        private void setItemDetails(int resource, String title, int freeCouponsNo, String productPriceText, String productCutPriceText, int offersAppliedNo) {
            productImage.setImageResource(resource);
            productTitle.setText(title);
            if (freeCouponsNo > 0) {
                freecouponIcon.setVisibility(View.VISIBLE);
                freeCoupons.setVisibility(View.VISIBLE);
                if (freeCouponsNo == 1) {
                    freeCoupons.setText("free " + freeCouponsNo + " Coupon");
                } else {
                    freeCoupons.setText("free " + freeCouponsNo + " Coupons");
                }
            } else {
                freecouponIcon.setVisibility(View.INVISIBLE);
                freeCoupons.setVisibility(View.INVISIBLE);
            }
            productPrice.setText(productPriceText);
            productCutPrice.setText(productCutPriceText);
            if (offersAppliedNo > 0) {
                offersApplied.setVisibility(View.VISIBLE);
                offersApplied.setText(offersAppliedNo + "Offers Applied");
            } else {
                offersApplied.setVisibility(View.INVISIBLE);
            }
        }
    }

    class CartTotalAmountViewHolder extends RecyclerView.ViewHolder {

        private TextView totalItems;
        private TextView totalItemPrice;
        private TextView conveniencePrice;
        private TextView totalAmount;
        private TextView savedAmount;

        public CartTotalAmountViewHolder(@NonNull View itemView) {
            super(itemView);
            totalItems = itemView.findViewById(R.id.total_items);
            totalItemPrice = itemView.findViewById(R.id.total_items_price);
            conveniencePrice = itemView.findViewById(R.id.convenience_price);
            totalAmount = itemView.findViewById(R.id.total_price);
            savedAmount = itemView.findViewById(R.id.saved_amount);
        }

        private void setTotalAmount(String totalItemText, String totalItemPriceText, String conveniencePriceText, String totalAmountText, String savedAmountText) {
            totalItems.setText(totalItemText);
            totalItemPrice.setText(totalItemPriceText);
            conveniencePrice.setText(conveniencePriceText);
            totalAmount.setText(totalAmountText);
            savedAmount.setText(savedAmountText);
        }
    }
}

这是完整的堆栈跟踪:

2019-08-01 09:51:45.298 26950-26950/com.example.fresh24 E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.fresh24, PID: 26950
    java.lang.ClassCastException: com.example.fresh24.CartAdapter$CartItemViewHolder cannot be cast to com.example.fresh24.CartAdapter$CartTotalAmountViewHolder
        at com.example.fresh24.CartAdapter.onBindViewHolder(CartAdapter.java:67)
        at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6781)
        at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6823)
        at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5752)
        at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6019)
        at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5858)
        at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5854)
        at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
        at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
        at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
        at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:612)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3924)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3641)
        at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4194)
        at android.view.View.layout(View.java:17523)
        at android.view.ViewGroup.layout(ViewGroup.java:5612)
        at androidx.constraintlayout.widget.ConstraintLayout.onLayout(ConstraintLayout.java:1915)
        at android.view.View.layout(View.java:17523)
        at android.view.ViewGroup.layout(ViewGroup.java:5612)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at android.view.View.layout(View.java:17523)
        at android.view.ViewGroup.layout(ViewGroup.java:5612)
        at com.google.android.material.appbar.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:142)
        at com.google.android.material.appbar.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:41)
        at com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1556)
        at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:888)
        at android.view.View.layout(View.java:17523)
        at android.view.ViewGroup.layout(ViewGroup.java:5612)
        at androidx.drawerlayout.widget.DrawerLayout.onLayout(DrawerLayout.java:1231)
        at android.view.View.layout(View.java:17523)
        at android.view.ViewGroup.layout(ViewGroup.java:5612)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at android.view.View.layout(View.java:17523)
        at android.view.ViewGroup.layout(ViewGroup.java:5612)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
        at android.view.View.layout(View.java:17523)
        at android.view.ViewGroup.layout(ViewGroup.java:5612)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at android.view.View.layout(View.java:17523)
        at android.view.ViewGroup.layout(ViewGroup.java:5612)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
        at android.view.View.layout(View.java:17523)
        at android.view.ViewGroup.layout(ViewGroup.java:5612)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
2019-08-01 09:51:45.298 26950-26950/com.example.fresh24 E/AndroidRuntime:     at com.android.internal.policy.DecorView.onLayout(DecorView.java:724)
        at android.view.View.layout(View.java:17523)
        at android.view.ViewGroup.layout(ViewGroup.java:5612)
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2342)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2069)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1246)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6301)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:871)
        at android.view.Choreographer.doCallbacks(Choreographer.java:683)
        at android.view.Choreographer.doFrame(Choreographer.java:619)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857)
        at android.os.Handler.handleCallback(Handler.java:751)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6077)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)

我已经阅读了有关 CastException 的文档，但无法找出错误的根源。请帮忙。提前致谢。

Answer 1

问题就在这里

View cartTotalView = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.cart_total_amount_layout, viewGroup, false);
return new CartItemViewHolder(cartTotalView); // Returning wrong ViewHolder it should be CartTotalAmountViewHolder