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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.collections4;

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.StringTokenizer;

import org.apache.commons.collections4.iterators.EnumerationIterator;

/**
 * Provides utility methods for {@link Enumeration} instances.
 *
 * @since 3.0
 * @version $Id: EnumerationUtils.java 1683009 2015-06-01 21:53:01Z tn $
 */
public class EnumerationUtils {

    /**
     * EnumerationUtils is not normally instantiated.
     */
    private EnumerationUtils() {}

    /**
     * Returns the index-th value in the {@link Enumeration}, throwing
     * IndexOutOfBoundsException if there is no such element.
     * 

* The Enumeration is advanced to index (or to the end, if * index exceeds the number of entries) as a side effect of this method. * * @param e the enumeration to get a value from * @param index the index to get * @param the type of object in the {@link Enumeration} * @return the object at the specified index * @throws IndexOutOfBoundsException if the index is invalid * @throws IllegalArgumentException if the object type is invalid * @since 4.1 */ public static T get(final Enumeration e, final int index) { int i = index; CollectionUtils.checkIndexBounds(i); while (e.hasMoreElements()) { i--; if (i == -1) { return e.nextElement(); } else { e.nextElement(); } } throw new IndexOutOfBoundsException("Entry does not exist: " + i); } /** * Creates a list based on an enumeration. * *

As the enumeration is traversed, an ArrayList of its values is * created. The new list is returned.

* * @param the element type * @param enumeration the enumeration to traverse, which should not be null. * @return a list containing all elements of the given enumeration * @throws NullPointerException if the enumeration parameter is null. */ public static List toList(final Enumeration enumeration) { return IteratorUtils.toList(new EnumerationIterator(enumeration)); } /** * Override toList(Enumeration) for StringTokenizer as it implements Enumeration<Object> * for the sake of backward compatibility. * * @param stringTokenizer the tokenizer to convert to a {@link List}<{@link String}> * @return a list containing all tokens of the given StringTokenizer */ public static List toList(final StringTokenizer stringTokenizer) { final List result = new ArrayList(stringTokenizer.countTokens()); while (stringTokenizer.hasMoreTokens()) { result.add(stringTokenizer.nextToken()); } return result; } }




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