001    /*--------------------------------------------------------------------------+
002    $Id: UnmodifiableIterator.java 26283 2010-02-18 11:18:57Z juergens $
003    |                                                                          |
004    | Copyright 2005-2010 Technische Universitaet Muenchen                     |
005    |                                                                          |
006    | Licensed under the Apache License, Version 2.0 (the "License");          |
007    | you may not use this file except in compliance with the License.         |
008    | You may obtain a copy of the License at                                  |
009    |                                                                          |
010    |    http://www.apache.org/licenses/LICENSE-2.0                            |
011    |                                                                          |
012    | Unless required by applicable law or agreed to in writing, software      |
013    | distributed under the License is distributed on an "AS IS" BASIS,        |
014    | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
015    | See the License for the specific language governing permissions and      |
016    | limitations under the License.                                           |
017    +--------------------------------------------------------------------------*/
018    package edu.tum.cs.commons.collections;
019    
020    import java.util.Iterator;
021    
022    /**
023     * This is a wrapper for a {@link Iterator} prohibiting all calls which would
024     * modify its owning container. All prohibited methods throw an
025     * {@link UnsupportedOperationException}.
026     * 
027     * @author Benjamin Hummel
028     * @author $Author: juergens $
029     * 
030     * @version $Revision: 26283 $
031     * @levd.rating GREEN Hash: 73D7E245FAE2147047C3C3D4B19E6C48
032     */
033    public class UnmodifiableIterator<E> implements Iterator<E> {
034    
035            /** The underlying iterator. */
036            private final Iterator<E> i;
037    
038            /**
039             * Creates a new unmodifiable iterator from another iterator. All
040             * modifications to the underlying iterator will directly be visible in this
041             * wrapper.
042             */
043            public UnmodifiableIterator(Iterator<E> i) {
044                    if (i == null) {
045                            throw new IllegalArgumentException(
046                                            "Underlying iterator may not be null!");
047                    }
048                    this.i = i;
049            }
050    
051            /** {@inheritDoc} */
052            public boolean hasNext() {
053                    return i.hasNext();
054            }
055    
056            /** {@inheritDoc} */
057            public E next() {
058                    return i.next();
059            }
060    
061            /**
062             * Operation is not supported.
063             * 
064             * @throws UnsupportedOperationException
065             */
066            public void remove() {
067                    throw new UnsupportedOperationException();
068            }
069    }