io.tilt.minka.utils.CircularCollection.java Source code

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Here is the source code for io.tilt.minka.utils.CircularCollection.java

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/*
 * 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 io.tilt.minka.utils;

import java.util.Collection;
import java.util.Iterator;

import org.apache.commons.lang.Validate;

public class CircularCollection<T> {
    Collection<T> source;
    Iterator<T> it;

    public CircularCollection(final Collection<T> collection) {
        Validate.notEmpty(collection);
        source = collection;
    }

    public T next() {
        if (it == null || !it.hasNext()) {
            it = source.iterator();
            if (!it.hasNext()) {
                return null;
            }
        }
        return it.next();
    }
}