java Collections.binarySearch 用法

package testCollections;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

/**
 * @Author: zhilei.wang
 * @Date: 2019/11/11 14:08
 * @Version 1.0
 */
public class TestCollection {
    public static void main(String[] args) {
        Student s1 = new Student("Alex", 10);
        Student s2 = new Student("Jerry", 20);
        Student s3 = new Student("Hustoy", 40);

        List<Student> students = new ArrayList<>();
        students.add(s1);
        students.add(s2);
        students.add(s3);

        // Collections.sort(students);

        //  int searchResult = Collections.binarySearch(students, new Student("Jerry", 20));
        int alex = Collections.binarySearch(students, new Student("Jerry", 20), new Comparator<Student>() {
            @Override
            public int compare(Student o1, Student o2) {
                //int num = this.age - o.age;
                int num = o1.getAge() - o2.getAge();
                int num1 = (num == 0 ? o1.getUsername().compareTo(o2.getUsername()) : num);
                return num1;
            }
        });

        System.out.println(alex);

    }
}

class Student /*implements Comparable<Student> */ {
    private String username;
    private int age;

    public Student(String username, int age) {
        this.username = username;
        this.age = age;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    /*
    @Override
    public int compareTo(Student o) {
        int num = this.age - o.age;
        int num1 = (num == 0 ? this.username.compareTo(o.username) : num);
        return num1;
    }

     */

}