java构造函数链接。为什么我要在这个（）中初始化一个参数

Question

下面是我的一节课。我有一个问题：为什么我要初始化第三个参数（名字，sal，“Gurgaon”）；在第三个构造函数public Employee1中（字符串名，int-sal）？我的意思是为什么我不能用“addr”代替初始化第三个参数-->；这个（名字，萨尔，地址）

public class Employee1 {
    public String name;
    public int salary;
    public String address;

    //default constructor of the class
    public Employee1()
    {
        //this will call the constructor with String param
        this("Chaitanya");
        System.out.println("Default");
    }

    public Employee1(String name)
    {
        //call the constructor with (String, int) param
        this(name, 120035);
        System.out.println(name);
    }
    public Employee1(String name, int sal)
    {
        //call the constructor with (String, int, String) param
        this(name, sal, "Gurgaon");
        System.out.println(name + " " + sal);
    }
    public Employee1(String name, int sal, String addr)
    {
        this.name=name;
        this.salary=sal;
        this.address=addr;
        System.out.println(name + " "+ sal + " " + addr);
    }

    public static void main(String[] args)
    {
        Employee1 obj = new Employee1();
    }
}

Answer 1

如果您没有调用最后一个以地址作为参数的构造函数，那么您的第二个构造函数将如下所示：

  public Employee1(String name, int sal)
  {
    //call the constructor with (String, int, String) param
    this.address = "Gurgaon";
    System.out.println(name + " "+ sal + " " + address);
  }

若地址未在此处初始化，地址将被打印为空。所以，就像上面的评论中提到的，你不需要调用最终的构造函数，如果你不想的话，甚至不需要调用一个