RoundRobin.java

/*
 * Copyright 2013 the original author or authors.
 *
 * 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 net.kuujo.vertigo.util;

import java.util.Iterator;
import java.util.List;

/**
 * Round robin iterator.
 *
 * @author <a href="http://github.com/kuujo">Jordan Halterman</a>
 *
 * @param <T> The iterated type.
 */
public class RoundRobin<T> implements Iterable<T> {
  private final List<T> list;
  private int size;

  public RoundRobin(List<T> list) {
    this.list = list;
    this.size = list.size();
  }

  @Override
  public Iterator<T> iterator() {
    this.size = list.size();
    return new Iterator<T>() {
      private int index;

      @Override
      public boolean hasNext() {
        return true;
      }

      @Override
      public T next() {
        index = index % size;
        return list.get(index++);
      }

      @Override
      public void remove() {
        throw new UnsupportedOperationException("Cannot remove items from list.");
      }
    };
  }

}