Android 应用程序：IndexOutOfBoundsException 我的应用程序在 运行 时崩溃

Question

This is the error I'm getting while running the app, If any additional details needed I can provide.

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.groceryshoppingsystem, PID: 13531 java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 at java.util.ArrayList.get(ArrayList.java:437) at com.example.groceryshoppingsystem.Adapters.GridproductAdapter.getView(GridproductAdapter.java:65)

我的适配器代码：

package com.example.groceryshoppingsystem.Adapters;
        
        import android.annotation.SuppressLint;
        import android.content.Context;
        import android.content.Intent;
        import android.view.LayoutInflater;
        import android.view.View;
        import android.view.ViewGroup;
        import android.widget.BaseAdapter;
        import android.widget.ImageView;
        import android.widget.TextView;
        import androidx.constraintlayout.widget.ConstraintLayout;
        import com.example.groceryshoppingsystem.Model.HorizontalProductModel;
        import com.example.groceryshoppingsystem.Model.favouritesClass;
        import com.example.groceryshoppingsystem.R;
        import com.example.groceryshoppingsystem.UI.ProductInfoActivity;
        import com.google.firebase.auth.FirebaseAuth;
        import com.google.firebase.database.DatabaseReference;
        import com.google.firebase.database.FirebaseDatabase;
        import com.squareup.picasso.Picasso;
        
        
        import java.util.List;
        
        public class GridproductAdapter extends BaseAdapter {
            List<HorizontalProductModel> horizontalProductModelList;
            ImageView productImage;
            TextView producttitle, productprice;
            ImageView checkBox;
            List<favouritesClass> favourites;
            ConstraintLayout Container;
            Context context;
        
            public GridproductAdapter(List<HorizontalProductModel> horizontalProductModelList, List<favouritesClass> favourites, Context context) {
                this.horizontalProductModelList = horizontalProductModelList;
                this.favourites = favourites;
                this.context = context;
            }
        
            @Override
            public int getCount() {
                return 4;
            }
        
            @Override
            public Object getItem(int position) {
                return null;
            }
        
            @Override
            public long getItemId(int position) {
                return 0;
            }
        
        
            @Override
            public View getView(final int position, View convertView, ViewGroup parent) {
        
                View view;
                if (convertView == null) {
                    view = LayoutInflater.from(parent.getContext()).inflate(R.layout.horizontal_item, null);
                    Container = view.findViewById(R.id.MainProductID);
                    productImage = view.findViewById(R.id.item_image);
                    producttitle = view.findViewById(R.id.item_title);
                    productprice = view.findViewById(R.id.item_Price);
                    checkBox = view.findViewById(R.id.check_box);
                    Picasso.get().load(horizontalProductModelList.get(position).getProductimage()).into(productImage);
                    producttitle.setText(horizontalProductModelList.get(position).getProducttitle());
                    productprice.setText("EGP "+horizontalProductModelList.get(position).getProductprice());
                    boolean isfavourite = false;
                    for (int i = 0; i < favourites.size(); i++) {
                        if (horizontalProductModelList.get(position).getProducttitle().equals(favourites.get(i).getProducttitle())) {
                            isfavourite = true;
                            horizontalProductModelList.get(position).setChecked(true);
                            break;
                        }
                    }
                    if (isfavourite) {
                        checkBox.setImageResource(R.drawable.ic_baseline_favorite_24);
                    } else
                        checkBox.setImageResource(R.drawable.ic_baseline_favorite_shadow_24);
                } else {
                    view = convertView;
                }
                checkBox.setOnClickListener(new View.OnClickListener() {
        
                    @Override
                    public void onClick(View v) {
                        DatabaseReference ref = FirebaseDatabase.getInstance().getReference("favourites")
                                .child(FirebaseAuth.getInstance().getCurrentUser().getUid());
                        HorizontalProductModel hz = horizontalProductModelList.get(position);
                        if (!(horizontalProductModelList.get(position).isChecked())) {
                            horizontalProductModelList.get(position).setChecked(true);
                            checkBox = v.findViewById(R.id.check_box);
                            checkBox.setImageResource(R.drawable.ic_baseline_favorite_24);
                            ref.child(horizontalProductModelList.get(position).getProducttitle()).setValue(hz);
                        } else {
                            horizontalProductModelList.get(position).setChecked(false);
                            checkBox = v.findViewById(R.id.check_box);
                            checkBox.setImageResource(R.drawable.ic_baseline_favorite_shadow_24);
                            ref.child(horizontalProductModelList.get(position).getProducttitle()).setValue(null);
                        }
                    }
                });
        
                Container.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        Intent intent = new Intent(context, ProductInfoActivity.class);
                        intent.putExtra("Product Name",horizontalProductModelList.get(position).getProducttitle());
                        intent.putExtra("Product Price",horizontalProductModelList.get(position).getProductprice());
                        intent.putExtra("Product Image",horizontalProductModelList.get(position).getProductimage());
                        intent.putExtra("Product ExpiryDate",horizontalProductModelList.get(position).getExpiredDate());
                        intent.putExtra("Product IsFavorite",String.valueOf(horizontalProductModelList.get(position).isChecked()));
                        intent.putExtra("Is Offered","no");
        
                        context.startActivity(intent);
                    }
                });
        
                return view;
            }
        
        }

Answer 1

@Override
public int getCount() {
    return 4;
}

您正在对适配器大小进行硬编码。适配器尝试在范围内查找项目

0<=positions<itemCount

当您将 itemCount 设置为 4 时，即使提供的列表为空，它也会搜索项目。

标准做法是将 itemCount 设置为与给定的列表大小相同。

Answer 2

@Override
public int getCount() {
    return horizontalProductModelList.size();
}

你可以直接给出列表的大小