Protects an given iterator by preventing calls to remove(). : Iterator « Collections Data Structure « Java

Protects an given iterator by preventing calls to remove().

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 * ---------------------
 * ---------------------
 * (C)opyright 2003, 2004, by Thomas Morgner and Contributors.
 * Original Author:  Thomas Morgner;
 * Contributor(s):   -;
 * $Id:,v 1.2 2005/10/18 13:24:19 mungady Exp $
 * Changes
 * -------------------------
 * 18-Jul-2003 : Initial version

import java.util.Iterator;

 * Protects an given iterator by preventing calls to remove().
 * @author Thomas Morgner
public class ReadOnlyIterator implements Iterator {

    /** The base iterator which we protect. */
    private Iterator base;

     * Creates a new read-only iterator for the given iterator.
     * @param it the iterator.
    public ReadOnlyIterator(final Iterator it) {
        if (it == null) {
            throw new NullPointerException("Base iterator is null.");
        this.base = it;

     * Returns <tt>true</tt> if the iteration has more elements. (In other
     * words, returns <tt>true</tt> if <tt>next</tt> would return an element
     * rather than throwing an exception.)
     * @return <tt>true</tt> if the iterator has more elements.
    public boolean hasNext() {
        return this.base.hasNext();

     * Returns the next element in the iteration.
     * Throws NoSuchElementException when iteration has no more elements.
     * @return the next element in the iteration.
    public Object next() {

     * Throws <code>UnsupportedOperationException</code>.
    public void remove() {
        throw new UnsupportedOperationException();


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