对ArrayList存放的对象，按照对象的某个属性进行排序。

使用Collections.sort()方法进行实现：

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

public class Child {
    private int id;
    private String name;
    
    public Child() {
        super();
    }
    public Child(int id, String name) {
        super();
        this.id = id;
        this.name = name;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public static void main(String[] args) {
        List<Child> list = new ArrayList<Child>();
        Child child1 = new Child(1,"aa");
        Child child2 = new Child(2,"bb");
        Child child3 = new Child(3,"cc");
        Child child4 = new Child(4,"dd");
        list.add(child1);
        list.add(child2);
        list.add(child3);
        list.add(child4);
        //对链表进行排序
        Collections.sort(list, new sortById());
        System.out.println("按照id进行排序：");
        for (Child child : list) {
            System.out.println(child.getId()+" "+child.getName());
        }
    }
}
//实现Comparator接口
class sortById implements Comparator{
    
    public int compare(Object o1, Object o2) {
        if(((Child)o1).getId()>((Child)o2).getId())
            return 1;
        return -1;
    }

}