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我有一个Employee用它的 2 个private变量调用的类，还包含它需要的构造函数和其他必要的方法：

public class Employee {

    private String name;
    private int id;

    public Employee() {
        name = " No Name!";
        id = 00100;
    }

    public Employee(String n, int i) {
        name = n;
        id = i;
    }

    public Employee(Employee originalObject) {
        name = originalObject.name;
        id = originalObject.id;
    }

    public String getName() {
        return name;
    }

    public int getID() {
        return id;
    }

    public void setName(String newName) {
        if (newName == null) {
            System.out.println("Fatal Error setting employee name!");
            System.exit(0);
        } else {
            name = newName;
        }
    }

    public void setID(int newID) {
        id = newID;
    }

    public String toString() {
        return (name + " " + id);
    }

    public boolean equals(Employee otherEmployee) {
        return (name.equals(otherEmployee.name)
                && id == otherEmployee.id);
    }
}

这个Employee类扩展了另一个名为 的类HourlyEmployee。扩展类如下：

public class HourlyEmployee extends Employee {

    private double wageRate;
    private double hours;

    public HourlyEmployee() {
        super();
        wageRate = 0;
        hours = 0;
    }

    public HourlyEmployee(String na, int di, double wR, double h) {
        super(na, di);
        if (wR >= 0 || h >= 0) {
            wageRate = wR;
            hours = h;
        } else {
            System.out.println("Fatal Error!: creating illegal hourly employee");
        }
        System.exit(0);
    }

    public HourlyEmployee(HourlyEmployee originalObject) {
        super(originalObject);
        wageRate = originalObject.wageRate;
        hours = originalObject.hours;
    }

    public double getRate() {
        return wageRate;
    }

    public double getHours() {
        return hours;
    }

    public double getPay() {
        return wageRate * hours;
    }

    public void setRate(double newWR) {
        if (newWR >= 0) {
            wageRate = newWR;
        } else {
            System.out.println("Fatal Error: negative hours worked!");
            System.exit(0);
        }
    }

    public String toString() {
        return (getName() + " " + getID() + "\n$" + wageRate + " per hour for " + hours + "hours");
    }
}

在我完成这个类的编码之后，我编写了 Demo 类来测试这些类以及它是如何工作的。

public class InheritanceDemo {

    public static void main(String[] args) {
        HourlyEmployee joe = new HourlyEmployee("Joe Worker", 281952, 50.50, 160);
        System.out.println("joe's longer name is " + joe.getName());
        System.out.println("Changing joe's name to joseph.");
        joe.setName("Joseph");
        System.out.println("joe's record is as follows: ");
        System.out.println(joe);
    }
}

最后，我尝试编译代码并且运行良好，但不幸的是，演示类没有运行，即使它在屏幕上向我显示“进程已完成”！你认为这个程序有什么问题？

解决方案

问题出System.exit(0)在HourlyEmployee. 由于没有{}之后else，退出是无条件执行的。