pjs/grendel/calypso/util/PrefetchEnumeration.java

92 строки
2.0 KiB
Java

/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil -*-
*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is the Grendel mail/news client.
*
* The Initial Developer of the Original Code is Netscape Communications
* Corporation. Portions created by Netscape are
* Copyright (C) 1997 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
*
* Created: Frank Tang <ftang@netscape.com>
*/
package calypso.util;
import java.util.Enumeration;
/*
*
* @author ftang
* @version $Revision: 1.2 $
* @see
*
*/
public abstract class PrefetchEnumeration implements Enumeration {
protected boolean initialized = false;
protected Object fFetch = null;
/*
*
* @author ftang
* @version $Revision: 1.2 $
* @see
*
*/
private void init()
{
if(! initialized )
{
fFetch = fetch();
initialized = true;
}
}
/*
*
* @author ftang
* @version $Revision: 1.2 $
* @see
*
*/
public Object nextElement()
{
if(! initialized)
init();
Object current = fFetch;
fFetch = fetch();
return current;
}
/*
*
* @author ftang
* @version $Revision: 1.2 $
* @see
*
*/
public boolean hasMoreElements()
{
if(! initialized)
init();
return (fFetch != null);
}
/*
*
* @author ftang
* @version $Revision: 1.2 $
* @see
*
*/
abstract protected Object fetch();
}