001/*-------------------------------------------------------------------------+
002|                                                                          |
003| Copyright 2005-2011 The ConQAT Project                                   |
004|                                                                          |
005| Licensed under the Apache License, Version 2.0 (the "License");          |
006| you may not use this file except in compliance with the License.         |
007| You may obtain a copy of the License at                                  |
008|                                                                          |
009|    http://www.apache.org/licenses/LICENSE-2.0                            |
010|                                                                          |
011| Unless required by applicable law or agreed to in writing, software      |
012| distributed under the License is distributed on an "AS IS" BASIS,        |
013| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
014| See the License for the specific language governing permissions and      |
015| limitations under the License.                                           |
016+-------------------------------------------------------------------------*/
017package org.conqat.lib.commons.collections;
018
019import java.util.Iterator;
020
021/**
022 * This is a wrapper for a {@link Iterator} prohibiting all calls which would
023 * modify its owning container. All prohibited methods throw an
024 * {@link UnsupportedOperationException}.
025 * 
026 * @author Benjamin Hummel
027 */
028public class UnmodifiableIterator<E> implements Iterator<E> {
029
030        /** The underlying iterator. */
031        private final Iterator<E> i;
032
033        /**
034         * Creates a new unmodifiable iterator from another iterator. All modifications
035         * to the underlying iterator will directly be visible in this wrapper.
036         */
037        public UnmodifiableIterator(Iterator<E> i) {
038                if (i == null) {
039                        throw new IllegalArgumentException("Underlying iterator may not be null!");
040                }
041                this.i = i;
042        }
043
044        /** {@inheritDoc} */
045        @Override
046        public boolean hasNext() {
047                return i.hasNext();
048        }
049
050        /** {@inheritDoc} */
051        @Override
052        public E next() {
053                return i.next();
054        }
055
056        /** Operation is not supported. */
057        @Override
058        public void remove() {
059                throw new UnsupportedOperationException();
060        }
061}