arrayListIterator object sort

import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.Collections;
import java.util.Random;

public class MyArrayListIterator
{
  public static void main( String args[] )
  {
    ArrayList <String> a =new ArrayList <String> ();
    System.out.println( a.size() );
    displayArrayList( a );
    a.add( "hi");
    System.out.println( a.size() );
    displayArrayListDetail( a );

   ArrayList <Contact> contactList = new ArrayList <Contact<();
   Contact john = new Contact( "john" , "my address" );
   Contact bobby = new Contact( "bobby" , "other address" );
   contactList.add( john );
   contactList.add( bobby );
   Collections.sort( contactList , Contact.COMPARE_BY_ADDRESS );

  } //end main

  private static void displayArrayList( ArrayList a )
  {
    ListIterator it =a.listIterator() ;     //ListIterator has prev and next , Iterator only goes forward
    while ( it.hasNext () )
    {
      System.out.println(  it.next() );
    }
  } //end displayArrayList()

  private static void displayArrayListDetail( ArrayList a )
  {
    int counter = 0;
    ListIterator it =a.listIterator() ;
    while ( it.hasNext () )
    {
      System.out.println("Element [" + counter + "] = " + it.next() );
      System.out.println(" -hasPrevious = " + it.hasPrevious( ) );
      System.out.println(" -hasNext = " + it.hasNext());
      System.out.println(" -previousIndex = " + it.previousIndex() ) ;
      System.out.println(" -nextIndex = " + it.nextIndex()) ;
      System.out.println();
       counter++;
     }
  } // end displayArrayListDetail


} //end class


// Natural Ordering = http://docs.oracle.com/javase/tutorial/collections/interfaces/order.html
// define an external controllable ordering (which overrides the natural ordering)

public class Contact
{
    private String name;
    private String address;

  Contact( String n , String a )
  {
    this.name = n;
    this.address = a;
  }

  // INSIDE OF THE DATA OBJECT CLASS inner class?
  protected static Comparator<StorageGateway> COMPARE_BY_ADDRESS = new Comparator<StorageGateway>()
  {
    public int compare( Contact first , Contact other )
    {
        return first.address.compareTo( other.address );    //this uses the Java Object Natural Ordering
    }
  };

} //end Contact class = data object