Mega Code Archive
De-mystify the Iterator interface, showing how to write a simple Iterator for an Array of Objects
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/*
* 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.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 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
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* 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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