Java: Implementing Iterable and Iterator to your Container Class

Iterator.java

import java.util.Iterator;

public class Iterators<Items> implements Iterable<Items>{

  private class Node {
    Items item;
    Node next;
  }

  private Node first = null;

  public void addItem(Items item) {
    Node newNode = new Node();
    newNode.item = item;
    newNode.next = null;

    if(first == null) {
      first = newNode;
    } else {
      Node current = first;
      while(current.next != null)
        current = current.next;
      current.next = newNode;
    }
  }

  public Iterator<Items> iterator() {
    return new nodeIterator();
  }


  private class nodeIterator implements Iterator<Items> {
    private Node reference = first;

    public boolean hasNext() {
      return reference != null;
    }

    public Items next () {
      Items result = reference.item;
      reference = reference.next;
      return result;
    }

    public void remove() {

    }
  }


  public static void main(String[] arguments) {
  	Iterators<Integer> integers = new Iterators<Integer>();
  	integers.addItem(3);
  	integers.addItem(4);
    integers.addItem(6);
    integers.addItem(7);

    // Thanks to Iterable and iterator.
    for(Integer storedNumber : integers)
      System.out.println(storedNumber);

  	Iterators<String> strings = new Iterators<String>();
  	strings.addItem("Hello");
  	strings.addItem("world");
    strings.addItem("Hola");

    // Another way to use iterators.
    Iterator stringIterator = strings.iterator();
    while(stringIterator.hasNext())
      System.out.println(stringIterator.next());

  }
}