java.lang.IndexOutOfBoundsException : 当我尝试从回收器视图列表中删除项目时

Question

当我尝试从列表中删除最后一项时，它会给我 IndexOutOfBound 错误，它只发生在列表中的最后一项。

这是我的代码

public class CartAdapter extends RecyclerView.Adapter<CartViewHolder> {
    private List<Order> listData = new ArrayList<>();
    private CartActivity cartActivity;
    private int total;
    public CartAdapter(List<Order> listData, CartActivity cartActivity) {
        this.listData = listData;
        this.cartActivity = cartActivity;
    }
    @NonNull
    @Override
    public CartViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        LayoutInflater inflater = LayoutInflater.from(cartActivity);
        View itemView = inflater.inflate(R.layout.cart_layout, viewGroup, false);
        return new CartViewHolder(itemView);
    }
    @Override
    public void onBindViewHolder(@NonNull final CartViewHolder cartViewHolder, @SuppressLint("RecyclerView") final int i) {
    cartViewHolder.counterButton.setNumber(listData.get(i).getQuantity());
        cartViewHolder.counterButton.setOnValueChangeListener(new ElegantNumberButton.OnValueChangeListener() {
            @Override
            public void onValueChange(ElegantNumberButton view, int oldValue, int newValue) {
                total = 0;
                Order order = listData.get(i);
                order.setQuantity(String.valueOf(newValue));
                new Database(cartActivity).updateCart(order);
                calculate();
            }
        });
        cartViewHolder.txt_price.setText(listData.get(i).getPrice());
        cartViewHolder.txt_cart_name.setText(listData.get(i).getFoodName());
        cartViewHolder.removeItem.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                listData.remove(i);
                notifyItemRemoved(i);
                notifyItemRangeChanged(i, listData.size());
                Order order = listData.get(i);
                new Database(cartActivity).clearItem(order);
                calculate();
            }
        });
    }
    private void calculate(){
        for (Order orders: listData){
            total += Integer.parseInt(orders.getPrice()) * Integer.parseInt(orders.getQuantity());
            Log.d("GDGDGD", String.valueOf(total));
        }
        int cgst = (total * 5)/100;
        total += cgst;
        Locale locale = new Locale("en","IN");
        NumberFormat fmt = NumberFormat.getCurrencyInstance(locale);
        cartActivity.txtTotalPrice.setText(fmt.format(total));
    }
}

上面的代码是来自回收器视图的片段，从数据库中获取的项目和列表。

Answer 1

问题是这一行：Order order = listData.get(i);

您首先删除了该项目，然后尝试获取订单。

listData.remove(i); // remove item from listData: it will have zero items if earlier, listData had one item
...
Order order = listData.get(i); // get ith order: will crash if listData's size is 0

将listData.remove(i);放在函数的末尾将解决此问题。

喜欢这个：

cartViewHolder.removeItem.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        notifyItemRemoved(i);
        notifyItemRangeChanged(i, listData.size());
        Order order = listData.get(i);
        new Database(cartActivity).clearItem(order);
        listData.remove(i);
        calculate();
    }
});

编辑：

在 calculate（） 中还有一个问题。您必须将变量total重新分配给零。

喜欢这个：

private void calculate(){
    total = 0;
    for (Order orders: listData){
        total += Integer.parseInt(orders.getPrice()) * Integer.parseInt(orders.getQuantity());
        Log.d("GDGDGD", String.valueOf(total));
    }
    int cgst = (total * 5)/100;
    total += cgst;
    Locale locale = new Locale("en","IN");
    NumberFormat fmt = NumberFormat.getCurrencyInstance(locale);
    cartActivity.txtTotalPrice.setText(fmt.format(total));
}

并删除total = 0;分配。喜欢这个：

    cartViewHolder.counterButton.setOnValueChangeListener(new ElegantNumberButton.OnValueChangeListener() {
        @Override
        public void onValueChange(ElegantNumberButton view, int oldValue, int newValue) {
            Order order = listData.get(i);
            order.setQuantity(String.valueOf(newValue));
            new Database(cartActivity).updateCart(order);
            calculate();
        }
    })