Java

Question

这是我设置的基本 class 计算股票收益的方法。在此处关注 "Stock" 构造函数：

public class Stock{
    private String symbol;
    private int totalShares;
    private double totalCost;

    public void Stock(String symbol){
        this.symbol = symbol;
        totalShares = 0;
        totalCost = 0.0;
    }

    public double getProfit(double currentPrice){
        double marketValue = totalShares * currentPrice;
        return marketValue - totalCost;
    }

    public void purchase(int shares, double pricePerShare){
        totalShares += shares;
        totalCost += shares*pricePerShare;
    }

    public int getTotalShares(){
        return totalShares;
    }
}

我创建了一个名为 DividendStock 的子class，它应该计算股息收益。

public class DividendStock extends Stock{
    private double dividends;

    public DividendStock(String symbol){
        super(symbol);
        dividends = 0.0;
    }

    public void payDividend(double amountPerShare){
        dividends += amountPerShare*getTotalShares();
    }
}

这个class的构造函数不允许我调用superclass的构造函数：super(symbol)；报错信息如下："constructor Stock in class Stock cannot be applied to given types;"

我已经搜索了解决方案，但似乎一切都已到位。为什么它不允许我调用这个构造函数的任何想法？

Answer 1

构造函数没有任何 return 类型。当你输入 return 类型时，它将是一个普通的方法。

public void Stock(String symbol) {
    this.symbol = symbol;
    totalShares = 0;
    totalCost = 0.0;
}

应该是

public Stock(String symbol) {
    this.symbol = symbol;
    totalShares = 0;
    totalCost = 0.0;
}

Answer 2

替换它public void Stock(String symbol){ this.symbol = symbol; totalShares = 0; totalCost = 0.0; }

到public Stock(String symbol){ this.symbol = symbol; totalShares = 0; totalCost = 0.0; }

Java - 调用超类的构造函数失败

Java - Calling the constructor of a superclass fails

constructor

subclass

superclass