package com.unit2.test; public class Test4 { public static void main(String[] args) { Salary s=new Salary("员工A","北京",3,3600.00); Employee e=new Salary("员工B","上海",2,2400.00); System.out.println("使用Salary的引用调用mailcheck--"); s.mailCheck(); System.out.println("\n使用employee的引用调用mailcheck--"); e.mailCheck(); } public class Employee{ private String name; private String address; private int number; public Employee(String name,String address,int number) { System.out.println("Employee 构造函数"); this.name=name; this.address=address; this.number=number; } public void mailCheck() { System.out.println("邮寄支票给："+this.name+" "+this.address); } public String toString() { return name+" "+address+" "+number; } public String getName() { return name; } public String getAddress() { return address; } public void setAddress(String newAddress) { address=newAddress; } public int getNumber() { return number; } } public class Salary extends Employee { private double salary;//全年工资 public Salary(String name,String address,int number,double salary) { super(name,address,number); setSalary(salary); } public void mailCheck() { System.out.println("Salary类的mailcheck方法"); System.out.println("邮寄支票给："+getName()+",工资为"+salary); } public double getSalary() { return salary; } public void setSalary(double newSalary) { if(newSalary>=0.0) { salary=newSalary; } } public double computePay() { System.out.println("计算工资，付给："+getName()); return salary/52; } } }更正以上代码错误

在以上代码中存在两个问题：

1. Test4类中定义了两个public类。Java中一个源文件中只能有一个public类，因此需要将Employee类和Salary类单独定义在不同的源文件中。

2. 在Employee类中没有定义getSalary()和setSalary()方法，而这两个方法在Salary类中被使用了，因此需要在Employee类中添加这两个方法。

以下是修改后的代码：

Employee.java

package com.unit2.test;

public class Employee{
    private String name;
    private String address;
    private int number;
    private double salary;

    public Employee(String name, String address, int number) {
        System.out.println("Employee 构造函数");
        this.name = name;
        this.address = address;
        this.number = number;
    }

    public void mailCheck() {
        System.out.println("邮寄支票给：" + this.name + " " + this.address);
    }

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

    public String getName() {
        return name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String newAddress) {
        address = newAddress;
    }

    public int getNumber() {
        return number;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double newSalary) {
        if (newSalary >= 0.0) {
            salary = newSalary;
        }
    }
}

Salary.java

package com.unit2.test;

public class Salary extends Employee {
    private double salary;//全年工资

    public Salary(String name, String address, int number, double salary) {
        super(name, address, number);
        setSalary(salary);
    }

    public void mailCheck() {
        System.out.println("Salary类的mailcheck方法");
        System.out.println("邮寄支票给：" + getName() + ",工资为" + salary);
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double newSalary) {
        if (newSalary >= 0.0) {
            salary = newSalary;
        }
    }

    public double computePay() {
        System.out.println("计算工资，付给：" + getName());
        return salary / 52;
    }
}

Test4.java

package com.unit2.test;

public class Test4 {
    public static void main(String[] args) {
        Salary s = new Salary("员工A", "北京", 3, 3600.00);
        Employee e = new Salary("员工B", "上海", 2, 2400.00);
        System.out.println("使用Salary的引用调用mailcheck--");
        s.mailCheck();
        System.out.println("\n使用employee的引用调用mailcheck--");
        e.mailCheck();
    }
}