创建方法时的类返回类型

Question

[UML图表] [1]

我正在为下周的期中考试而学习，我正在练习我教授的一些例子。但是，我在使用类返回类型方法时遇到了一些麻烦。

我附上了UML图以防万一。

我想要了解的是Job类中的getPerson方法。我认为我不需要Job类中的数组列表来存储所有员工。因为我在公司类中已经有一个数组列表。返回类型也是Employee类，我不知道如何使用此类返回类型获取人员信息。

我的问题

1. 公共员工getPerson（）{}在Job类
中
2. Job类中的公共布尔值isVacant（）{}
3. 如果正确构建了getVacantJobs，getFilledJobs和getAllJobs方法，你还要介意吗？

我使用iterator显示所有存储的作业。

---------------------------员工类------------------ -----------

public class Employee {
    private String name;
    private int id;

    public Employee(int id, String name) {
        this.name = name;
        this.id =id;

    }

    public final String getName() {
        return name;
    }

    public final void setName(String name) {
        this.name = name;
    }

    public final int getId() {
        return id;
    }

    public final void setId(int id) {
        this.id = id;
    }

    @Override
    public String toString() {
        return "Employee [name=" + name + ", id=" + id + "]";
    }

}

---------------------------- Job Class ----------------- ---------------------

public class Job {

    private String description;

    private int id;
    private double maxSalary;

    public Job(int id, double maxSalary, String description) {
        this.description = description;
        this.id = id;
        this.maxSalary = maxSalary;
    }

    public Job(int id, double maxSalary, String description, Employee e1) {
        this.description = description;
        this.id = id;
        this.maxSalary = maxSalary;



    }

    @Override
    public String toString() {

        return "Job [description=" + description + ", id=" + id
                + ", maxSalary=" + maxSalary + "]";
    }

    public final String getDescription() {
        return description;
    }

    public final void setDescription(String description) {
        this.description = description;
    }

    public final double getMaxSalary() {
        return maxSalary;
    }

    public final void setMaxSalary(double maxSalary) {
        this.maxSalary = maxSalary;
    }

    public final int getId() {
        return id;
    }

    public Employee getPerson() {
        retrun 
    }

    public final void setPerson(Employee person) {
        this.id = person.getId();

    }
}

--------------------------公司类------------------- --------

import java.util.ArrayList;
import java.util.Iterator;

public class Company {

    static ArrayList list = new ArrayList();
    Iterator itr = list.iterator();


    private String name;

    public Company(String name) {
        this.name = name;
    }

    public Company() {
        // TODO Auto-generated constructor stub
    }

    public static void addJob(Job j1) {
        list.add(j1);
    }

    public void removeJob(int id) {
        list.remove(id);

    }


    public ArrayList<Job> getVacantJobs() {
        while (itr.hasNext()) {
            if ((itr == null)) {
                System.out.println(itr);
            }
        }
        return null;

    }

    public ArrayList<Job> getFilledJobs() {
        while (itr.hasNext()) {
            if (!(itr == null)) {
                System.out.println(itr);
            }
        }
        return null;
    }

    public ArrayList<Job> getAllJobs() {
        while (itr.hasNext()) {
            System.out.println(itr.next());
        }
        return null;
    }

}

Answer 1

将字段person添加到Job类。

public class Job {

    // .....

    private Employee person;

    public Employee getPerson() {
        return person;
    }

    public final void setPerson(Employee person) {
        this.person = person;
    }

    public boolean isVacant() {
        return person == null;
    }
}

并将jobs字段添加到Company类。

public class Company {

    // static ArrayList list = new ArrayList();  // You don't need this
    // Iterator itr = list.iterator();  // You don't need this.

    // .....

    private ArrayList<Job> jobs = new ArrayList<>();

    public ArrayList<Job> getVacantJobs() {
        ArrayList<Job> result = new ArrayList<>();
        for (Job job : jobs)
            if (job.isVacant())
                result.add(job);
        return result;
    }

    public ArrayList<Job> getFilledJobs() {
        ArrayList<Job> result = new ArrayList<>();
        for (Job job : jobs)
            if (!job.isVacant())
                result.add(job);
        return result;
    }

    public ArrayList<Job> getAllJobs() {
        ArrayList<Job> result = new ArrayList<>();
        for (Job job : jobs)
            result.add(job);
        return result;
    }
}