// Simple client to interact with ListNode.
public class ListNodeClient {
   public static void main(String[] args) {
      ListNode front = new ListNode(10);
      front.next = new ListNode(20);
      front.next.next = new ListNode(30);
      
      // Hardcoded to print out this 3 element list
      // System.out.println(front.data);
      // System.out.println(front.next.data);
      // System.out.println(front.next.next.data);

      // Standard traversal for a linked list
      // start at the front
      ListNode current = front;
      while (current != null) { // loop until the end
         // do something with the data
         System.out.println(current.data);
         
         // move to the next
         current = current.next;
      }
   }

}