java - 构造函数设置/获取。如何设置不返回小于0的值？

Question

为每个实例变量提供一个set和一个get方法。如果月薪非正数，则不要设置其值。

我遇到的问题是“未设置值”这是我的代码:

Main.class

public class Main {

public static void main(String[] args) {

Employee myEmp  = new Employee("William", "Russell", 30000);
Employee myEmp2  = new Employee("Yevgeniya", "Pakhom", -1);
myEmp.displayMessage();
myEmp2.displayMessage();
}
}

Employee.class


public class Employee {

    private String fName;
    private String lName;
    private double ySalary;

public Employee (String firstName, String lastName, double yearSalary)
    {
        fName = firstName;
        lName = lastName;
        ySalary = yearSalary;
    }
// Set First Name
    public void setFName (String firstName)
        {
        fName = firstName;
        }
// Get First Name
    public String getFName()
        {
        return fName;
        } 

   // Set Last Name
    public void setLName (String lastName)
        {
        lName = lastName;
        }
  //  Get Last Name
    public  String getLName()
        {
        return lName;
        } 

 // Set Salary
    public void setSalary (double yearSalary)
        {

            ySalary = yearSalary;

        }
// Get Salary
    public double getYearSalary()
        {

        return ySalary;

        }
// Display method
        public void displayMessage()
        {
            if (ySalary < 0)
                 System.out.printf("Hello %s %s, \nI see you're       currently making: %.2f\n", getFName(), getLName(),getYearSalary() );


 }
}

我在 displayMessage() 方法中放置了一条 if 语句。但我想这并不是“将其设置为空”。

我的妻子也有类似的问题，她将其设置在“获取”下，但我的却没有以同样的方式工作。

Answer 1

将 setSalary 更改为

public void setSalary (double yearSalary)
        {
            if (yearSalary <= 0) {
                 throw new IllegalArgumentException("yearSalary: " + yearSalary);
            }
            ySalary = yearSalary;
        }