问如何对用户定义对象的链表进行排序？

EN

import java.io.*;
import java.util.*;

public class ABook
{
   public static void main (String args[])
   {
       LinkedList addressBook = new LinkedList(); 
      

       Scanner input = new Scanner(System.in);
       int n = 0; 
       do{
       System.out.println("Would you like to add a friend? (Say Y or N)"); 
       String reply = input.nextLine();
       if(reply.equals("Y"))
       {
        System.out.println("What is the name of your friend?");
        String name = input.nextLine();
        System.out.println("What is the age of your friend?");
        int age = input.nextInt();
        Friend newFriend = new Friend(name,age);
        addressBook.add("Name: " + newFriend.name + "; " + "Age: " + newFriend.age);
         Comparator<CustomObject> comparator = new Comparator<CustomObject>() {
           public int compare(CustomObject c1, CustomObject c2) {
               return c2.getAge() - c1.getAge(); // use your logic
              }


       Collections.sort(addressBook,comparator);
        System.out.println("This is your Address Book so far: " + addressBook);
        n++;
    }     
      ...
}