Sorting ArrayList of Arraylist in java

Question

I have an ArrayList of ArrayList of String.

In Outer ArrayList on each index each Inner ArrayList has four items have four parameters.

1. Contacts Id

Answer 1

You should create a class for your data structure (if you can't, then specify why. I can't see any good reason not to):

public class Contact implements Comparable {
    private String id;
    private String name;
    private String address;
    private String number;

    // Getters and setters, and compareTo.
}

Then use that in your list instead:

List<Contact> contacts = new ArrayList<Contacts>();

Sorting it will then be trivial.