An enumeration that iterates over an array. : Enumeration Interface « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. Enumeration Interface

/**
 * 
 * JFreeReport : a free Java reporting library
 * 
 *
 * Project Info:  http://reporting.pentaho.org/
 *
 * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * ------------
 * ArrayEnumeration.java
 * ------------
 * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
 */


import java.util.Enumeration;
import java.util.NoSuchElementException;

/**
 * An enumeration that iterates over an array.
 *
 * @author Thomas Morgner

 */
public class ArrayEnumeration implements Enumeration
{
  /** The base datasource. */
  private Object[] objectarray = null;
  /** The counter holds the current position inside the array. */
  private int counter = 0;

  /**
   * Creates a new enumeration for the given array.
   *
   * @param objectarray the array over which to iterate
   * @throws NullPointerException if the array is null.
   */
  public ArrayEnumeration(final Object[] objectarray)
  {
    if (objectarray == null)
    {
      throw new NullPointerException("The array must not be null.");
    }

    this.objectarray = objectarray;
  }

  /**
   * Returns true if this enumeration has at least one more Element.
   *
   * @return true, if there are more elements, false otherwise.
   */
  public boolean hasMoreElements()
  {
    return (counter < objectarray.length);
  }

  /**
   * Returns the next element in the Array.
   *
   * @return the next element in the array.
   * @throws  NoSuchElementException  if no more elements exist.
   */
  public Object nextElement()
  {
    if (counter >= objectarray.length)
    {
      throw new NoSuchElementException();
    }

    final Object retval = objectarray[counter];
    counter += 1;
    return retval;
  }
}