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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;

import static java.util.Arrays.asList;

public class ChainingIterator extends UnaryReferenceIterator {
	private final Iterator> iterables;

	@SafeVarargs
	public ChainingIterator(Iterable... iterables) {
		this(asList(iterables));
	}

	public ChainingIterator(Iterable> iterables) {
		this.iterables = iterables.iterator();
	}

	@Override
	public boolean hasNext() {
		while ((iterator == null || !iterator.hasNext()) && iterables.hasNext()) {
			@SuppressWarnings("unchecked")
			Iterator iterator = (Iterator) iterables.next().iterator();
			this.iterator = iterator;
		}
		return iterator != null && iterator.hasNext();
	}

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