org.apache.hadoop.hdfs.util.TestCyclicIteration.java Source code

Introduction

Here is the source code for org.apache.hadoop.hdfs.util.TestCyclicIteration.java

Source

/**
 * 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.hadoop.hdfs.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.NavigableMap;
import java.util.TreeMap;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class TestCyclicIteration extends junit.framework.TestCase {
    static final Log LOG = LogFactory.getLog(TestCyclicIteration.class);

    public void testCyclicIteration() throws Exception {
        for (int n = 0; n < 5; n++) {
            checkCyclicIteration(n);
        }
    }

    private static void checkCyclicIteration(int numOfElements) {
        //create a tree map
        final NavigableMap<Integer, Integer> map = new TreeMap<Integer, Integer>();
        final Integer[] integers = new Integer[numOfElements];
        for (int i = 0; i < integers.length; i++) {
            integers[i] = 2 * i;
            map.put(integers[i], integers[i]);
        }
        LOG.info("\n\nintegers=" + Arrays.asList(integers));
        LOG.info("map=" + map);

        //try starting everywhere
        for (int start = -1; start <= 2 * integers.length - 1; start++) {
            //get a cyclic iteration
            final List<Integer> iteration = new ArrayList<Integer>();
            for (Map.Entry<Integer, Integer> e : new CyclicIteration<Integer, Integer>(map, start)) {
                iteration.add(e.getKey());
            }
            LOG.info("start=" + start + ", iteration=" + iteration);

            //verify results
            for (int i = 0; i < integers.length; i++) {
                final int j = ((start + 2) / 2 + i) % integers.length;
                assertEquals("i=" + i + ", j=" + j, iteration.get(i), integers[j]);
            }
        }
    }
}