java - 的 TreeSet 列表对列表进行排序并显示列表中具有特定属性的人员

Question

我有一个 Employee 列表(Employee 是一个类)。员工有 3 个属性

private String name    
private int yearsSpentInCompany
private boolean parkingSpace

并且具有这些属性的构造函数

 public Employee(String name, int yearsSpentInCompany, boolean parkingSpace) {
        this.name = name;
        this.yearsSpentInCompany = yearsSpentInCompany;
        this.parkingSpace = parkingSpace;}

一览是这个

List<Employee> allEmployeesOfCompany = new ArrayList<Employee>();

例如，我的列表中有 10 名员工。我如何获取没有任何 parking 位的员工列表(parkingSpace = false)，以及根据在公司工作的年限排序的相同列表。

我不完整的解决方案:我在公司工作多年定义了自己的比较器

import java.util.Comparator;

public class YearsComp implements Comparator<Employee> {

    @Override
    public int compare(Employee o1, Employee o2) {
        if (o1.getYearsSpentInCompany() > o2.getYearsSpentInCompany()) {
            return 1;
        } else {
            return -1;
        }
    }
}

输出为

=== Employees sorted by seniority in work === 
Employee: Vlad === YearsSpentInCompany: 1 === ParkingPlace:true
Employee: Ayian === YearsSpentInCompany: 2 === ParkingPlace:true
Employee: Ion === YearsSpentInCompany: 2 === ParkingPlace:true
Employee: Victor === YearsSpentInCompany: 2 === ParkingPlace:false
Employee: Aurel === YearsSpentInCompany: 8 === ParkingPlace:false
Employee: Tudod === YearsSpentInCompany: 10 === ParkingPlace:true
Employee: Sebi === YearsSpentInCompany: 13 === ParkingPlace:true
Employee: Marcel === YearsSpentInCompany: 15 === ParkingPlace:false
Employee: Raul === YearsSpentInCompany: 16 === ParkingPlace:true
Employee: Andrei === YearsSpentInCompany: 17 === ParkingPlace:false

排序很好。 Emplyee 类在该类中实现了 Comparable 和 i Ovveride:

@Override
public int compareTo(Object o) {
        if( this.parkingSpace == false)
            System.out.println("No parking place: " + this.getName());
        return 0;
    }

输出为

No parking place: Marcel  ---15 years
No parking place: Aurel   ---- 8 years
No parking place: Victor   ---- 2 years
No parking place: Andrei    --- 17 years

这部分正确，因为我想按照在这样的公司工作的年限对没有 parking 位的员工进行排序

No parking place: Victor   ---- 2 years
No parking place: Aurel   ---- 8 years
No parking place: Marcel  ---15 years
No parking place: Andrei    --- 17 years

如何结合这两种方法？

Answer 1

使用 compareTo 来获取没有 parking 场的员工是没有意义的。 compareTo 应该用于排序(以及 TreeSet 中的唯一性测试)，而不是用于过滤。

您可以使用 Java 8 Stream 轻松过滤和排序:

List<Employee> output =
    allEmployeesOfCompany.stream()
                         .filter(emp -> !emp.parkingSpace)
                         .sorted(Comparator.comparingInt(Employee::getYearsSpentInCompany))
                         .collect(Collectors.toList());