De-mystify the Iterator interface, showing how to write a simple Iterator for an Array of Objects

    
/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 *    notice, this list of conditions and the following disclaimer in the
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 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */

import java.util.Iterator;

/**
 * De-mystify the Iterator interface, showing how to write a simple Iterator for
 * an Array of Objects.
 * 
 * @author Ian Darwin, http://www.darwinsys.com/
 * @version $Id: ArrayIterator.java,v 1.10 2004/06/16 17:39:33 ian Exp $
 */
public class ArrayIterator implements Iterator {
  /** The data to be iterated over. */
  protected Object[] data;

  protected int index = 0;

  /**
   * Construct an ArrayIterator object.
   * 
   * @param d
   *            The array of objects to be iterated over.
   */
  public ArrayIterator(final Object[] d) {
    setData(d);
  }

  /**
   * (Re)set the data array to the given array, and reset the iterator.
   * 
   * @param d
   *            The array of objects to be iterated over.
   */
  public void setData(final Object[] d) {
    this.data = d;
    index = 0;
  }

  /**
   * Tell if there are any more elements.
   * 
   * @return true if not at the end, i.e., if next() will succeed.
   * @return false if next() will throw an exception.
   */
  public boolean hasNext() {
    return (index < data.length);
  }

  /** Returns the next element from the data */
  public Object next() {
    if (hasNext()) {
      return data[index++];
    }
    throw new IndexOutOfBoundsException("only " + data.length + " elements");
  }

  /**
   * Remove the object that next() just returned. An Iterator is not required
   * to support this interface, and we certainly don't!
   */
  public void remove() {
    throw new UnsupportedOperationException(
        "This demo does not implement the remove method");
  }
}

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6.	Iterate a Collection and remove an item (Exception, wrong version)
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9.	EmptyIterator is an iterator which is empty.
10.	Implements an java.util.Iterator over any array
11.	Treat an Iterator as an Iterable
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14.	Array Iterator
15.	Cyclic Iteration
16.	Create singleton Iterator
17.	Empty Iterator
18.	An Iterator that wraps a number of Iterators
19.	An Iterator to iterate over the elements of an array
20.	Sorted Iterator
21.	Iterator Union of Iterators
22.	Iterator Utils
23.	Linked Iterator
24.	Prefetch Iterator
25.	Protects an given iterator by preventing calls to remove().
26.	An Iterator that returns the elements of a specified array, or other iterators etc.
27.	An Iterator wrapper for an Object[], allow us to deal with all array like structures in a consistent manner.
28.	An array iterator
29.	Adapt iterator to iterable
30.	Static utility methods, classes, and abstract classes for iteration.
31.	Iterator Collection
32.	Convert Iterable to List
33.	A singleton null object Iterator implementation.

De-mystify the Iterator interface, showing how to write a simple Iterator for an Array of Objects : Iterator « Collections Data Structure « Java

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