001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  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.apache.commons.collections4;
018
019import java.util.ArrayList;
020import java.util.Enumeration;
021import java.util.List;
022import java.util.StringTokenizer;
023
024import org.apache.commons.collections4.iterators.EnumerationIterator;
025
026/**
027 * Provides utility methods for {@link Enumeration} instances.
028 *
029 * @since 3.0
030 * @version $Id: EnumerationUtils.html 972421 2015-11-14 20:00:04Z tn $
031 */
032public class EnumerationUtils {
033
034    /**
035     * EnumerationUtils is not normally instantiated.
036     */
037    private EnumerationUtils() {}
038
039    /**
040     * Creates a list based on an enumeration.
041     *
042     * <p>As the enumeration is traversed, an ArrayList of its values is
043     * created. The new list is returned.</p>
044     *
045     * @param <E> the element type
046     * @param enumeration  the enumeration to traverse, which should not be <code>null</code>.
047     * @return a list containing all elements of the given enumeration
048     * @throws NullPointerException if the enumeration parameter is <code>null</code>.
049     */
050    public static <E> List<E> toList(final Enumeration<? extends E> enumeration) {
051        return IteratorUtils.toList(new EnumerationIterator<E>(enumeration));
052    }
053
054    /**
055     * Override toList(Enumeration) for StringTokenizer as it implements Enumeration&lt;Object&gt;
056     * for the sake of backward compatibility.
057     *
058     * @param stringTokenizer  the tokenizer to convert to a {@link List}&lt;{@link String}&gt;
059     * @return a list containing all tokens of the given StringTokenizer
060     */
061    public static List<String> toList(final StringTokenizer stringTokenizer) {
062        final List<String> result = new ArrayList<String>(stringTokenizer.countTokens());
063        while (stringTokenizer.hasMoreTokens()) {
064            result.add(stringTokenizer.nextToken());
065        }
066        return result;
067    }
068}