/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* 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 eu.stratosphere.pact.runtime.util;
import eu.stratosphere.util.MutableObjectIterator;
/**
* An empty mutable object iterator that never returns anything.
*
*/
public final class EmptyMutableObjectIterator<E> implements MutableObjectIterator<E> {
/**
* The singleton instance.
*/
private static final EmptyMutableObjectIterator<Object> INSTANCE = new EmptyMutableObjectIterator<Object>();
/**
* Gets a singleton instance of the empty iterator.
*
* @param <E> The type of the objects (not) returned by the iterator.
* @return An instance of the iterator.
*/
public static <E> MutableObjectIterator<E> get() {
@SuppressWarnings("unchecked")
MutableObjectIterator<E> iter = (MutableObjectIterator<E>) INSTANCE;
return iter;
}
/**
* Always returns null.
*
* @see MutableObjectIterator#next(Object)
*/
@Override
public E next(E target) {
return null;
}
}