com.feilong.lib.collection4.EnumerationUtils Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of feilong Show documentation
feilong is a suite of core and expanded libraries that include utility classes, http, excel,cvs, io classes, and much much more.
There is a newer version: 4.3.0
Show newest version
/*
 * 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 com.feilong.lib.collection4;

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

import com.feilong.lib.collection4.iterators.EnumerationIterator;

/**
 * Provides utility methods for {@link Enumeration} instances.
 *
 * @since 3.0
 */
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();
            }
            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;
    }
}