Java 中的构造函数重载

public class employee {
    private string name;
    private int id;
    private double salary;

    // constructor 1: no parameters
    public employee() {
        this.name = "unknown";
        this.id = 0;
        this.salary = 0.0;
    }

    // constructor 2: one parameter (name)
    public employee(string name) {
        this.name = name;
        this.id = 0;
        this.salary = 0.0;
    }

    // constructor 3: two parameters (name and id)
    public employee(string name, int id) {
        this.name = name;
        this.id = id;
        this.salary = 0.0;
    }

    // constructor 4: three parameters (name, id, and salary)
    public employee(string name, int id, double salary) {
        this.name = name;
        this.id = id;
        this.salary = salary;
    }

    public void displayinfo() {
        system.out.println("name: " + name + ", id: " + id + ", salary: " + salary);
    }
}

public class main {
    public static void main(string[] args) {
        // using the no-argument constructor
        employee emp1 = new employee();
        emp1.displayinfo(); // output: name: unknown, id: 0, salary: 0.0

        // using the constructor with one argument
        employee emp2 = new employee("alice");
        emp2.displayinfo(); // output: name: alice, id: 0, salary: 0.0

        // using the constructor with two arguments
        employee emp3 = new employee("bob", 123);
        emp3.displayinfo(); // output: name: bob, id: 123, salary: 0.0

        // using the constructor with three arguments
        employee emp4 = new employee("charlie", 456, 50000.0);
        emp4.displayinfo(); // output: name: charlie, id: 456, salary: 50000.0
    }
}

public Employee(String name) {
    this(name, 0, 0.0); // Calls the constructor with three parameters
}