如何更新包含多个值的arrayList？

Question

我正在创建一个存储到arraylist(项目键,数量和项目的价格)的篮子.如何仅更新数量而不是使用相同的Item键创建另一行.以下是该程序的结果.

Java Book                 1   £48.90

Samsung Galaxy S7         1   £639.50


Speakers                  3   £59.80


Java Book                 2   £48.90


Samsung Galaxy S7         2   £639.50

//////////////////////////////////////////////////

private void ItemsBasket(String name, int qty, String key) throws HeadlessException {

        if (name == null) {
            JOptionPane.showMessageDialog(null, "Please Selecet a key");
            String imageFileName = "./images/" + key + ".png";
            File imageFile = new File(imageFileName);

            if (!imageFile.exists()) {
                imageFileName = "./images/empty.png";
            }

        } else if (qty <= StockData.getQuantity(key)) {


            arList.add(StockData.getName(key) + "\t\t  " + qty + "   " + pounds.format(StockData.getPrice(key)));

            bagtotal += StockData.getPrice(key) * qty;

            JOptionPane.showMessageDialog(null, "Sucessfully added to the basket");

        } else {
            JOptionPane.showMessageDialog(null, "Insuffcient stock");
            JOptionPane.showMessageDialog(null, "Available items qty : " + "**" + StockData.getQuantity(key) + "**");

        }
    }

Answer 1

创建一个StockData对象并将其直接添加到ArrayList<StockData>

public class StockData{
    String name;
    int qty;
    double price;

    public StockData(String n, int q, double p){
    // Initialization
    }
}

然后,使用setter,您可以修改您的对象中的对象的数据 List

arList.get(index).setName("NewName");