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'databene commons' is an open source Java library by Volker Bergmann.
It provides extensions to the Java core library by utility classes, abstract concepts
and concrete implementations.
/*
* Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
* All rights reserved.
*
* Licensed 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.databene.commons.iterator;
import java.util.Iterator;
/**
* {@link Iterator} implementation which allows to preview the {@link #next()} value
* without actually consuming it using the {@link #peek()} method.
* Created: 25.01.2012 14:11:17
* @param the type to iterate
* @since 0.5.14
* @author Volker Bergmann
*/
public class PreviewIterator extends IteratorProxy {
private boolean hasNext;
private E next;
public PreviewIterator(Iterator source) {
super(source);
fetchNext();
}
public E peek() {
return this.next;
}
// Iterator interface implementation -------------------------------------------------------------------------------
@Override
public boolean hasNext() {
return hasNext;
}
@Override
public E next() {
E result = this.next;
fetchNext();
return result;
}
// private helpers -------------------------------------------------------------------------------------------------
private void fetchNext() {
this.hasNext = source.hasNext();
this.next = (this.hasNext ? source.next() : null);
}
}