Question

嗨，我是Java的新手，试图学习基础知识，我一直在研究构造函数方法并遇到问题

public class Employee {
int emp_id;
String name;
String Depart;
double Salary;
double bonus;
boolean resident;

public Employee() {
    emp_id = 1;
    name = "null";
    Depart = "General";
    Salary = 0.0;
    bonus = 0.0;
    resident = true;
}

public Employee(int x , String y) {
    x = emp_id;
    y = name;
}

public Employee(int x , String y , boolean b) { 
    this (x,y);
    b = resident;
}

public void print_emp() {
    System.out.println("Employee name = "+ name +"\nHis ID is : " + emp_id + "\nHis department is : "+ Depart + "\nResidency = " + resident + "\nHis salary = "+Salary);
}

public static void main(String[] args) {

    Employee e1 = new Employee(20,"Ali");

    e1.set_dept("Auto");
    e1.print_emp();
}

}

当我尝试打印时，它只是为我提供了默认的构造函数值：

Employee name = null
His ID is : 0
His department is : null
Residency = false
His salary = 0.0

出什么问题了？

Answer 1

分配是从左到右

emp_id = x;
name = y;

Answer 2

在这两个构造函数中，您可以向后进行赋值操作：

public Employee(int x , String y) {
    x = emp_id;
    y = name;
}
public Employee(int x , String y , boolean b) { 
    this (x,y);
    b = resident;
}

分配是从左到右的，因此应该这样写：

public Employee(int x , String y) {
    emp_id = x;
    name = y;
}
public Employee(int x , String y , boolean b) { 
    this (x,y);
    resident = b;
}

编译器不会传递构造函数的值

2 个答案: