Need help sorting 2 arrays linked by their indexes

Question

I have 2 arrays that have been linked by the index of both arrays. The first array has to be sorted alphabetically, so I need a way to sort the 2nd array so that the indices match up again with the first array.
Now, I cannot change my ArrayList (i.e. TreeSet, List, etc.) since there is lots of code that would have to be changed. Here is my test code. Hopefully everyone is a fan of the television show Friends so that you can see how if I sort the firstName Array alphabetically, then I have to have the 2nd array sorted to be "linked" back to the first array based on the index. I am looking for ideas, but if you have simple code, that would be great too.
import java.util.*;
public class Test
     public static void main(String[] args)
          System.out.println("BEGIN TEST...");
Test test = new Test();
test.beginTest();
System.out.println("\nTEST COMPLETE!");
     public Test(){}
     public void beginTest()
          ArrayList firstName = new ArrayList();
          ArrayList lastName = new ArrayList();
          //Add to firstName ArrayList
          firstName.add("Ross");
          firstName.add("Chandler");
          firstName.add("Rachel");
          firstName.add("Phoebe");
          firstName.add("Joey");
          //Add to lastName ArrayList
          lastName.add("Geller");
          lastName.add("Bing");
          lastName.add("Green");
          lastName.add("Buffay");
          lastName.add("Tribbiani");
          try
               System.out.println("TESTING...\n");
               for(int index=0; index<firstName.size(); index++)
                    String first = firstName.get(index).toString();
                    String last = lastName.get(index).toString();
                    System.out.println("Hi, I am " + first + " " + last + ".");                    
          catch(Exception X) { System.out.println("EXCEPTION! "+X); X.printStackTrace(); }
}

Answer 1

Keeping the list in synch is conceptually easy.
Basically anything you do to the one List, you have to do to the other in order to keep them consistent.
How are you sorting your "firstnames" list?
Using the Collections.sort method, or some manual coding?
Would it be possible to change your datastructure from "parallel arrays" to "List of people objects"
iepublic class Person {
  String firstName;
  String lastName;
  public Person(String firstName, String lastName){
    this.firstName = firstName;
    this.lastName = lastName;
  // appropriate getter/setter methods
}Then you could build up your list like this:
List friends = new ArrayList();
friends.add(new Person("Ross", "Geller"));
friends.add(new Person("Chandler", "Bing"));
  ...Now when you sort the list, the last name always goes with the first name because they are in the same object.
You then write different Comparator objects to impose different orderings.
Hope this helps,
evnafets