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package org.apache.catalina.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 <code>Enumeration</code> around a Java2
* collection classes object <code>Iterator</code> 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: 1.2 $ $Date: 2005/12/08 01:28:15 $
*/
public final class Enumerator<T> implements Enumeration<T> {
// ----------------------------------------------------------- Constructors
/**
* Return an Enumeration over the values of the specified Collection.
*
* @param collection Collection whose values should be enumerated
*/
public Enumerator(Collection<T> 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<T> 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<T> iterator) {
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<T> iterator, boolean clone) {
if (!clone) {
this.iterator = iterator;
} else {
List<T> list = new ArrayList<T>();
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<?, T> 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<?, T> map, boolean clone) {
this(map.values().iterator(), clone);
}
// ----------------------------------------------------- Instance Variables
/**
* The <code>Iterator</code> over which the <code>Enumeration</code>
* represented by this class actually operates.
*/
private Iterator<T> iterator;
// --------------------------------------------------------- Public Methods
/**
* Tests if this enumeration contains more elements.
*
* @return <code>true</code> if and only if this enumeration object
* contains at least one more element to provide, <code>false</code>
* 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();
}
}