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A lightweight alternative to Java 8 sequential Stream

There is a newer version: 2.3.0

/*
 * Copyright 2015 Daniel Skogquist Åborg
 *
 * 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.d2ab.iterator;

import javax.annotation.Nullable;
import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * An {@link Iterator} that cycles the values of an {@link Iterable} forever. This class repeatedly calls
 * {@link Iterable#iterator()} to receive new values when the iterator ends, so it's possible to cause this
 * {@link Iterator} to terminate by providing an empty {@link Iterator}. If the {@link Iterable} never returns an
 * empty {@link Iterator}, this {@link Iterator} will never terminate.
 */
public class RepeatingIterator extends UnaryReferenceIterator {
	private final Iterable iterable;
	private long times;

	public RepeatingIterator(Iterable iterable, long times) {
		this.iterable = iterable;
		this.times = times;
	}

	@Override
	public boolean hasNext() {
		if ((iterator == null || !iterator.hasNext()) && times != 0) {
			if (times > 0)
				times--;

			@SuppressWarnings("unchecked")
			Iterator iterator = (Iterator) iterable.iterator();
			this.iterator = iterator;
		}
		return iterator != null && iterator.hasNext();
	}

	@Override
	@Nullable
	public T next() {
		if (!hasNext())
			throw new NoSuchElementException();

		return iterator.next();
	}
}