对 对象的指定属性就行排序

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

public class StudentDeom {
    public static void main(String[] args) {
        List<Student> list=new ArrayList<Student>();
        Student s1 = new Student("张三",20);
        Student s2 = new Student("lisu",52);
        Student s3 = new Student("awn",60);
        Student s4 = new Student("kk",32);
    list.add(s1);
    list.add(s2);
    list.add(s3);
    list.add(s4);
        Collections.sort(list);
        System.out.println( list);


    }
}

public class Student implements Comparable {

    public Student(String name, int age) {

        this.name = name;
        this.age = age;
    }

    private  String name;
     private int age;


    public int getAge() {
        return age;
    }

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

    public String getName() {
        return name;
    }

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

    @Override
    public String toString() {
        return "Student{" +
                "age=" + age +
                ", name='" + name + '\'' +
                '}';
    }

    @Override
    public int compareTo(Object o) {
        Student student=(Student) o;
        return this.getAge()-student.getAge();
    }
}