从重写的子类方法调用超类方法

Question

我确信这有一个简单的解决方案，但我是 Java 新手，无法解决。

我有一个扩展超类 Pay 的子类 Payroll，它包含一个名为“calc_payroll”的重写方法。从这个方法中，我想调用同名的超类方法，并将输出分配给覆盖方法中的一个变量。我的代码如下

public class Payroll extends Pay
{
   public double calc_Payroll()
{
    double grossPay = super.calc_Payroll();
    double taxAmt = tax(grossPay);
    double netPay = grossPay - taxAmt;  

    System.out.println(grossPay);

    return netPay;
}


}

下面是超类中 calc_payroll 方法的代码

public double calc_Payroll()
{
    double otRate = rate * 1.77;
    double otHours = ttlHours - stHours;

    if(stHours == 0)
    {
        grossPay = otHours * rate;
    }

    else
    {
        grossPay = ((stHours * rate) + (otHours * otRate));
    }

    System.out.println(stHours + "//" + otHours + "//" + rate);//for testing

    return grossPay;
}

当从不同的子类调用时，超类方法可以毫无问题地计算并返回总工资，但是当从具有相同名称的方法调用它时，上面代码中的打印行（我已标记为用于测试）为所有变量显示零

完整的“支付”类代码如下所示

public class Pay
{
private double ttlHours;
private int stHours;
private double rate;
double grossPay = 0.0;
final double TAXL = 0.07;
final double TAXM = 0.1;
final double TAXH = 0.16;

public void SetHours(double a)
{
    ttlHours = a;
}

public void SetHoursStr(int a)
{
    stHours = a;
}

public void SetRate(double a)
{
    rate = a;
}

public double GetHours()
{
    return ttlHours;
}

public int GetStHours()
{
    return stHours;
}

public double GetRate()
{
    return rate;
}

public double taxRate()
{
    double taxRate = 0.0;

    if(grossPay <= 399.99)
    {
        taxRate = TAXL;
    }
    else if(grossPay <= 899.99)
    {
        taxRate = TAXM;         
    }
    else
    {
        taxRate = TAXH;
    }

    return taxRate;
}

public double tax(double grossPay)
{
    double ttlTax = 0.0;        

    if(grossPay < 400.00)
    {
        ttlTax += (grossPay * TAXL); 
    }

    else if(grossPay < 900.00)
    {
        ttlTax += (grossPay * TAXM);
    }

    else
    {
        ttlTax += (grossPay * TAXH);
    }

    return ttlTax;
}

public double calc_Payroll()
{
    double otRate = rate * 1.77;
    double otHours = ttlHours - stHours;

    if(stHours == 0)
    {
        grossPay = otHours * rate;
    }

    else
    {
        grossPay = ((stHours * rate) + (otHours * otRate));
    }

    System.out.println(stHours + "//" + otHours + "//" + rate);//for testing

    return grossPay;
}
}

子类 Payroll 不包含其他代码

下面是接受用户输入为初始化变量赋值的代码

public class CalPayroll extends Pay
{
Payroll nPay = new Payroll();
Accept Read = new Accept(); 


public void AcceptPay()
{
    char select = '0';

    while(select != 'e' && select != 'E')
        {
            System.out.println("Payroll Computation \n");           
            System.out.print("Enter number of hours worked (00.0) <0 for Quick exit>: ");
            SetHours(Read.AcceptInputDouble());
            System.out.print("Enter first number of hours straight (integer or 0 to disable): ");
            SetHoursStr(Read.AcceptInputInt());
            System.out.print("Enter hourly rate of worker (00.00): ");
            SetRate(Read.AcceptInputDouble());
            Screen.ScrollScreen('=', 66, 1);
            Screen.ScrollScreen(1); 
            displayInfo();
            System.out.println("e to exit, any other letter + <Enter> to continue");
            select = Read.AcceptInputChar();
        }
}

public void displayInfo()
{       
    NumberFormat currency = NumberFormat.getCurrencyInstance();
    NumberFormat percent = NumberFormat.getPercentInstance();

    System.out.println("Gross pay is :" + currency.format(calc_Payroll()));
    System.out.println("Tax is :" + percent.format(taxRate()));
    System.out.println("Net pay is :" + currency.format(nPay.calc_Payroll()));      
    Screen.ScrollScreen(1);     
}


}

我很困惑！

Answer 1

从您的代码中可以清楚地看出，ttlHours, stHours and rate 没有使用一些合理的值进行初始化。因此，当您只调用 super.calc_Payroll() 时，会使用像 0 or 0.0 这样的值，正如我在评论中所解释的那样。最好在调用super.calc_Payroll() 之前先设置这些变量的值。

SetHours(23.4);  //some value

SetHoursStr(5);   //some value

SetRate(2.3);   //some value

另外，您没有 Pay 类的构造函数，请尝试创建它并在构造函数中初始化所有未初始化的变量，或使用 setter/getter 方法设置和获取值。

由于您的两个类都扩展了 Pay 类，因此会产生您面临的问题。当你调用SetHours(Read.AcceptInputDouble())时，它设置了CalPayroll从Pay继承的变量，而不是Payroll类继承的变量。您需要做的是为Payroll 实例和当前类设置变量，因为它们都扩展了Pay。执行以下操作将您的 while 循环替换为，

while(select != 'e' && select != 'E')
        {
            System.out.println("Payroll Computation \n");           
            System.out.print("Enter number of hours worked (00.0) <0 for Quick exit>: ");
            SetHours(Read.AcceptInputDouble());
            nPay.SetHours(GetHours());
            System.out.print("Enter first number of hours straight (integer or 0 to disable): ");
            SetHoursStr(Read.AcceptInputInt());
            nPay.SetHoursStr(GetStHours());
            System.out.print("Enter hourly rate of worker (00.00): ");
            SetRate(Read.AcceptInputDouble());
            nPay.SetRate(GetRate());
            Screen.ScrollScreen('=', 66, 1);
            Screen.ScrollScreen(1); 
            displayInfo();
            System.out.println("e to exit, any other letter + <Enter> to continue");
            select = Read.AcceptInputChar();
        }

Answer 2

请发布完整的代码。 似乎由于某种原因，您的超类方法的变量没有正确分配值。并且它们使用默认值进行初始化，这使所有内容都为 0。如果您粘贴完整的类，我将能够提供更好的帮助。