| /** |
| * 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 static org.junit.Assert.assertEquals; |
| |
| 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.junit.Test; |
| |
| public class TestCyclicIteration { |
| @Test |
| 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]); |
| } |
| System.out.println("\n\nintegers=" + Arrays.asList(integers)); |
| System.out.println("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()); |
| } |
| System.out.println("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]); |
| } |
| } |
| } |
| } |