org.apache.flink.runtime.util.SingleElementIterator 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.flink.runtime.util;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* An {@link Iterator} that contains only a single element. The element can be reset such that the iterator can be used
* multiple times. Initially, the iterator is empty until an element is set via {@link #set(Object)}.
*
* @param The generic type of the iterator.
*/
public final class SingleElementIterator implements Iterator, Iterable {
private E current;
private boolean available = false;
/**
* Resets the element. After this call, the iterator has one element available, which is the given element.
*
* @param current The element to make available to the iterator.
*/
public void set(E current) {
this.current = current;
this.available = true;
}
@Override
public boolean hasNext() {
return available;
}
@Override
public E next() {
if (available) {
available = false;
return current;
} else {
throw new NoSuchElementException();
}
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
@Override
public Iterator iterator() {
return this;
}
}