org.apache.jasper.util.Enumerator Maven / Gradle / Ivy
/*
* 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.jasper.util;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
/**
* Adapter class that wraps an Enumeration around a Java2
* collection classes object Iterator so that existing APIs
* returning Enumerations can easily run on top of the new collections.
* Constructors are provided to easily create such wrappers.
*
* @author Craig R. McClanahan
* @version $Id: Enumerator.java 1044164 2010-12-09 23:30:15Z markt $
*/
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 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 true if and only if this enumeration object
* contains at least one more element to provide, false
* otherwise
*/
@Override
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
*/
@Override
public T nextElement() throws NoSuchElementException {
return (iterator.next());
}
}