Java 默认构造函数问题声明值

主要

public class Employee {

     public  Employee(){
        id=-1;
        year=-1;
        salary=-1; 
        name="NA";
        department="NA"; 
    }

    public  Employee(int id ,String name ,String department, int year,double salary){
        String s="Sales";
        String i="IT";
        String W="Warehouse";
        if(department.equals(W)) {
            this.department=department;}
        else 
            if(department.equals(s)) {
                this.department=department;}
            else 
                if(department.equals(i)) {
                    this.department=department;}
                else 
                    System.out.print("Department was not set"); 
    }

我的问题是我在默认构造函数中声明了设置

int input,id ,year ;
double salary;
String name ,department; 

System.out.print("Enter Employee 1 details (id, name, department, years, salary)");
id=kb.nextInt(); 
name=kb.next(); 
department=kb.next();
year=kb.nextInt(); 
salary=kb.nextDouble();  
Employee Employee=new Employee(id, name, department, year, salary);

但当用户输入无效值时，它会打印null或0

我试着用

id=-1;
year=-1;
salary=-1; 
name="NA";
department="NA";

---

但它同样打印

null

或

0

。任何问题所在的想法都包括从全参数构造函数调用默认构造函数

Employee Employee=new Employee();
Employee=new Employee(id, name, department, year, salary);

问题是

public Employee(int id, String name, String department, int year, double salary) {
    this();
    // the rest

}

及

是独立的，后者只设置一个

部门

字段，而您希望所有字段都被设置

new Employee(id, name, department, year, salary)

这意味着“首先填充默认值”

这个构造函数

 this();

这也是一个问题。它需要很多论点，但只适用于一个论点。考虑将它们设置为

 Employee(int id, String name, String department, int year, double salary)

验证条件可以简化

this.id = id;
// and others

---

您有多个构造函数。是否将参数分配给类变量

public Employee（int-id，String-name，String-department，int-year，double-salary）{this.id=id；this.name=name；….}

通常情况下，这是另一种方式。参数较少的构造函数调用参数较多的构造函数并传递默认值，即

this（-1，“NA”，“NA”，-1，-1）

this.id = id;
// and others

if (department.equals(W) || department.equals(s) || department.equals(i)) {
    this.department = department;
} else {
    // a message or exception 
}