定义类名Money

Question

我坚持使用add/subtract方法来定义一个名为money的类，该类的对象表示美国货币的数量。该类应该有两个类型为int的实例变量，分别表示美元和美分的金额。包括一个构造函数和一个无参数构造函数，其中一个构造函数具有两个类型为int的参数，其中一个构造函数的类型为int，其中一个类型的构造函数用于美元的数量为零美分。包括用于对金额进行加法和减法加法和减法，并返回money类型的值。包括一组合理的访问器和赋值器方法，以及方法equals和toString。

再一次，我被加/减部分卡住了，就是不能确定它。另外，equals部分有点令人困惑。是的，这是家庭作业。我在尽我最大的努力，但需要一点推动力。

请看一下……

public class Money {

    private static  int dollars;
    private static int cents;

    public Money()
    {

    }

    public Money(int dollars, int cents)
    {
        this.dollars = dollars;
        this.cents = cents;
    }

    public Money(int dollars)
    {
        this.dollars = dollars;
    }



    public int getDollars() {
        return dollars;
    }

    public void setDollars(int dollars) {
        this.dollars = dollars;
    }

    public int getCents() {
        return cents;
    }

    public void setCents(int cents) {
        this.cents = cents;
    }


    public static Money add(Money m1, Money m2)
    {
        int cash = m1.dollars + m2.dollars;
        int change = m1.cents + m2.cents;
        return new Money(dollars, cents);


    }

    public static int MinusMoney(int m3, int m4)
    {
        return (m3-m4);
    }
    public boolean equals(double YourMoney)
    {
        boolean result;
        if (YourMoney > 0)
        {
            dollars += cents;
            result = true;
        }
        else
        {
            result = false;
        }
        return result;


    }

    public String toString()
    {
        return ("$" + getDollars() + "." + getCents());
    }

    public static void main(String[] args)
    {
        Money MyMoney = new Money(2,30);

        System.out.println("You have " + MyMoney.toString());

        Money MyMoney1 = new Money(2,30);
        Money MyMoney2 = new Money(3,10);

        System.out.println("You now have " + Money.add(MyMoney1, MyMoney2));

    }

}

Answer 1

这些要求指出，对对象的操作(如add和subtract)返回一个新实例，而不是更改当前实例。因此：

class Money {
    private int dollars;
    private int cents;

    public Money(int dollars, int cents) {
        if (dollars < 0 || cents < 0)
            throw new IllegalArgumentException("Negative dollars or cents");
        this.dollars = dollars;
        this.cents = cents;
    }

    public Money add(Money other) {
        int cents = this.cents + other.cents;
        return new Money(this.dollars + other.dollars + cents / 100, cents % 100);
    }
}

对于equals，这通常被定义为覆盖Object.equals，这意味着它需要接受Object而不是double

public boolean equals(Object other) {
    return other != null && other.getClass() == Money.class
        && this.dollars == (Money)other.dollars
        && this.cents == (Money)other.cents;
}

Answer 2

自从发帖后，我有了一点更新。我算出了加/减，它起作用了。感谢您的相等部分，但其中出现了一个问题。

public boolean equals(Object other) {
    return other != null && other.getClass() == Money.class
        && this.dollars == (Money)other.dollars
        && this.cents == (Money)other.cents

关于other.getClass()的部分...Are你指的是Money类，或者这是我需要添加更多方法的东西？

public class Money {

    private int dollars;
    private int cents;

    public Money()
    {

    }

    public Money(int dollars, int cents)
    {
        this.dollars = dollars;
        this.cents = cents;
    }

    public Money(int dollars)
    {
        this.dollars = dollars;
    }



    public int getDollars() {
        return dollars;
    }

    public void setDollars(int dollars) {
        this.dollars = dollars;
    }

    public int getCents() {
        return cents;
    }

    public void setCents(int cents) {
        this.cents = cents;
    }

    public static Money add(Money m1, Money m2)
    {
        int dollars1 = m1.getDollars();
        int dollars2 = m2.getDollars();
        int cents1 = m1.getCents();
        int cents2 = m2.getCents();

        int sumDollars = dollars1 + dollars2;
        int sumCents = cents1 + cents2;

        if(sumCents > 100)
        {
            sumDollars = sumDollars +1;
            sumCents = sumCents - 100;
        }
        Money output = new Money(sumDollars, sumCents);
        return output;


    }

    public static Money minus(Money m1, Money m2)
    {
        int dollars1 = m1.getDollars();
        int dollars2 = m2.getDollars();
        int cents1 = m1.getCents();
        int cents2 = m2.getCents();

        int sumDollars = dollars1 - dollars2;
        int sumCents = cents1 - cents2;

        if(sumCents > 100)
        {
            sumDollars = sumDollars +1;
            sumCents = sumCents - 100;
        }
        Money output = new Money(sumDollars, sumCents);
        return output;


    }
    public boolean equals(double YourMoney)
    {
        boolean result;
        if (YourMoney > 0)
        {
            dollars += cents;
            result = true;
        }
        else
        {
            result = false;
        }
        return result;
    }

    public String toString()
    {
    return ("$" + getDollars() + "." + getCents());
    }

    public static void main(String[] args)
{
    Money MyMoney = new Money(2,30);

        System.out.println("You have " + MyMoney.toString());

        Money MyMoney1 = new Money(12,30);
        Money MyMoney2 = new Money(7,10);

        System.out.println("You now have " + Money.minus(MyMoney1, MyMoney2));

}

}

Answer 3

你使用了两个属性，一个是美元，一个是美分，这让事情变得复杂起来。在method itself.Then中，您可以简单地将美元转换为美分并传递美分，或者将美元转换为美分。使用method可以轻松地执行计算。你可以通过以下方式来完成

totalcents1= dollar1*100 +cent1;
totalcents2= dollar2*100 + cent2;
//for add
return totalcents1+totalcents2;
//for substract do check which is greater
return totalcents1-totalcents2;

1美分对1美元的反向过程