java - 错误: Actual and formal argument lists differ in length?

Question

我正在尝试完成购物车建模类(class)。

这是我的代码:

public class ShoppingCart {
    private double price;
    private double subTotal;
    private double cart;

    /**
     * initializing variable named subTotal
     */
    public ShoppingCart() {
        subTotal = 0;
    }

    /**
     * adds this cost to the subtotal for this ShoppingCart
     *
     * @param addPrice Any double value that will be added
     */
    public void add(double addPrice) {
        subTotal = subTotal + addPrice;
    }

    /**
     * subtracts this cost from the subtotal for this ShoppingCart
     *
     * @param subtractPrice Any double value that will be subtracted
     */
    public void remove(double subtractPrice) {
        subTotal = subTotal - subtractPrice;
    }

    /**
     * gets the subtotal for this ShoppingCart
     *
     * @param totalCost Any double value that will be the total amount
     * @return the cost of things in ShoppingCart
     */
    public double getSubtotal(double totalCost) {
        totalCost = subTotal;
        return subTotal;
    }
}


public class ShoppingCartTester {
    public static void main(String[] args) {
        ShoppingCart cart = new ShoppingCart();
        cart.add(10.25);
        cart.add(1.75);
        cart.add(5.50);
        System.out.println(cart.getSubtotal());
        System.out.println("Expected: 17.5");
        cart.remove(5.50);
        cart.add(3);
        System.out.println(cart.getSubtotal());
        System.out.println("Expected: 15.0");
    }
}

来自 System.out.println(cart.getSubtotal()); 我收到一个错误，指出实际参数列表和形式参数列表的长度不同。

Answer 1

您收到此错误是因为该方法需要传入 double 值，但您在不带参数的情况下调用它。

您可以将 getSubtotal 方法更改为如下所示，它只会在添加后返回小计变量的值:

public double getSubtotal() {
    return subTotal;
}

这应该会给你你想要的结果!