从本身是目标对象的变量的对象访问 Java 对象的变量？

Question

我已经编写了三个Java类：

• Company
• Department
• Employee

每个Company对象都包含一个Department对象的数组，而这些对象又包含Employee对象的数组。

我想在Employee类setQid()中编写一个方法，该方法将以以下格式为该员工设置一个唯一的ID：

• compName_deptName_deptNumber_empFirstName_empSurname

示例：

• "Microsoft_Accounting_3_John_Smith">

我的问题是：如何从Employee类的上下文中访问以下变量？

Company中的String name

Department中的String name

Department中的int number

请参阅下面的代码：

public class Company {
private String name;
private Department[] departments;
public Company(String name, Department[] departments) {
this.name = name;
this.departments = departments;
}
}

public class Department {
private String name;
private int number;
private Employee[] members;
public Department(String name, int number, Employee[] members) {
this.name = name;
this.number = number;
this.members = members;
}
}

public class Employee {
private String firstname;
private String surname;
private String qid; //A unique employee ID
public Employee(String firstname, String surname) {
this.firstname = firstname;
this.surname = surname;
setQid();
}
public void setQid() {
// How can I access the Company name, Department name, and Department number from here?
}
}

Answer 1

您需要在Employee类中有一个Department的引用，在Department中也有一个Company的引用，只有这样，您与实体之间的关系才会完整。

public class Company {
private String name;
private Department[] departments;
public Company(String name, Department[] departments) {
this.name = name;
this.departments = departments;
}
//add getters and setters
}
public class Department {
private String name;
private int number;
private Employee[] members;
private Company company;
public Department(String name, int number, Employee[] members) {
this.name = name;
this.number = number;
this.members = members;
}

//add getters and setters
}
public class Employee {
private String firstname;
private String surname;
private String qid; //A unique employee ID
private Department department;
public Employee(String firstname, String surname) {
this.firstname = firstname;
this.surname = surname;
setQid();
}
public void setQid() {

qid = department.getCompany().getName + "_" + department.getName() ....
}
//add getters and setters
}