Tomcat example source code file (Enumerator.java)

This example Tomcat source code file (Enumerator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

arraylist, enumeration, enumeration, enumerator, enumerator, iterator, iterator, list, nosuchelementexception, object, object, util

The Tomcat Enumerator.java source code

/*
 * 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.catalina.util;


import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.NoSuchElementException;


/**
 * Adapter class that wraps an <code>Enumeration around a Java2
 * collection classes object <code>Iterator so that existing APIs
 * returning Enumerations can easily run on top of the new collections.
 * Constructors are provided to easliy create such wrappers.
 *
 * @author Craig R. McClanahan
 * @version $Revision: 467222 $ $Date: 2006-10-24 05:17:11 +0200 (mar., 24 oct. 2006) $
 */

public final class Enumerator implements Enumeration {


    // ----------------------------------------------------------- Constructors


    /**
     * Return an Enumeration over the values of the specified Collection.
     *
     * @param collection Collection whose values should be enumerated
     */
    public Enumerator(Collection collection) {

        this(collection.iterator());

    }


    /**
     * Return an Enumeration over the values of the specified Collection.
     *
     * @param collection Collection whose values should be enumerated
     * @param clone true to clone iterator
     */
    public Enumerator(Collection collection, boolean clone) {

        this(collection.iterator(), clone);

    }


    /**
     * Return an Enumeration over the values returned by the
     * specified Iterator.
     *
     * @param iterator Iterator to be wrapped
     */
    public Enumerator(Iterator iterator) {

        super();
        this.iterator = iterator;

    }


    /**
     * Return an Enumeration over the values returned by the
     * specified Iterator.
     *
     * @param iterator Iterator to be wrapped
     * @param clone true to clone iterator
     */
    public Enumerator(Iterator iterator, boolean clone) {

        super();
        if (!clone) {
            this.iterator = iterator;
        } else {
            List list = new ArrayList();
            while (iterator.hasNext()) {
                list.add(iterator.next());
            }
            this.iterator = list.iterator();   
        }

    }


    /**
     * Return an Enumeration over the values of the specified Map.
     *
     * @param map Map whose values should be enumerated
     */
    public Enumerator(Map map) {

        this(map.values().iterator());

    }


    /**
     * Return an Enumeration over the values of the specified Map.
     *
     * @param map Map whose values should be enumerated
     * @param clone true to clone iterator
     */
    public Enumerator(Map map, boolean clone) {

        this(map.values().iterator(), clone);

    }


    // ----------------------------------------------------- Instance Variables


    /**
     * The <code>Iterator over which the Enumeration
     * represented by this class actually operates.
     */
    private Iterator iterator = null;


    // --------------------------------------------------------- Public Methods


    /**
     * Tests if this enumeration contains more elements.
     *
     * @return <code>true if and only if this enumeration object
     *  contains at least one more element to provide, <code>false
     *  otherwise
     */
    public boolean hasMoreElements() {

        return (iterator.hasNext());

    }


    /**
     * Returns the next element of this enumeration if this enumeration
     * has at least one more element to provide.
     *
     * @return the next element of this enumeration
     *
     * @exception NoSuchElementException if no more elements exist
     */
    public Object nextElement() throws NoSuchElementException {

        return (iterator.next());

    }


}