比较器Comparator

import java.util.*;
class Student {
    String name;
    int id,age;
    Student(String name,int id,int age) {
        this.name = name;
        this.id = id;
        this.age = age;
    }
}
public class ComparetorTest {
    public static class MyCompara implements Comparator<Student> {
        public int compare(Student s1, Student s2) {
            return s1.age - s2.age;
        }
    }
    public static void main(String[] args) {
        Student s1 = new Student("A",1,22);
        Student s2 = new Student("B",3,23);
        Student s3 = new Student("C",2,21);
        Student[] student = new Student[] {s1,s2,s3};
        Arrays.sort(student, new MyCompara());
        for(int i = 0;i < student.length;i++) 
            System.out.println(student[i].name + " " + student[i].id + " " + student[i].age);
    }
}