// validating/CountedList.java // (c)2017 MindView LLC: see Copyright.txt // We make no guarantees that this code is fit for any purpose. // Visit http://OnJava8.com for more book information. // Keeps track of how many of itself are created. package validating; import java.util.*; public class CountedList extends ArrayList { private static int counter = 0; private int id = counter++; public CountedList() { System.out.println("CountedList #" + id); } public int getId() { return id; } }