java - 该语句如何工作 : "static final Comparator SENIORITY_ORDER = new Comparator() {};"

Question

我正在学习 Java，我在 Youtube 上看到了下面的代码。我只是想知道这部分代码是如何工作的。

static final Comparator<Employee> SENIORITY_ORDER = 
                                            new Comparator<Employee>() {
                public int compare(Employee e1, Employee e2) {
                    return e2.hireDate().compareTo(e1.hireDate());
                }
        };

有人可以给我解释一下吗？预先感谢您的帮助!

import java.util.*;
public class EmpSort {
    static final Comparator<Employee> SENIORITY_ORDER = 
                                        new Comparator<Employee>() {
            public int compare(Employee e1, Employee e2) {
                return e2.hireDate().compareTo(e1.hireDate());
            }
    };

    // Employee database
    static final Collection<Employee> employees = ... ;

    public static void main(String[] args) {
        List<Employee> e = new ArrayList<Employee>(employees);
        Collections.sort(e, SENIORITY_ORDER);
        System.out.println(e);
    }
}

Answer 1

SENIORITY_ORDER Comparator(用于比较排序中的Employee)是一个 Anonymous Class 。链接的 Java 教程(部分)

Anonymous classes enable you to make your code more concise. They enable you to declare and instantiate a class at the same time. They are like local classes except that they do not have a name. Use them if you need to use a local class only once.