arrilist陣列和collections儲存學生排序

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

public class Main {
    public static void main(String[] args) {
        ArrayList<Student> arrayList = new ArrayList<>();
        Student s1 = new Student("zsf", 24);
        Student s2 = new Student("jcs", 23);
        Student s3 = new Student("zxt", 24);

        arrayList.add(s1);
        arrayList.add(s2);
        arrayList.add(s3);

        Collections.sort(arrayList, new Comparator<Student>() {
            @Override
            public int compare(Student o1, Student o2) {
                int num = 0;
                num = o1.getAge() - o2.getAge();
                int num2 = num == 0 ? o1.getName().compareTo(o2.getName()) : num;


                return num2;
            }


        });
        for (Student s : arrayList) {
            System.out.println("姓名 " + s.getName() + " 年齡" + s.getAge());
        }

    }
}

public class Student {
    private String name;
    private int age;

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

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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