001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.math3.stat.descriptive.rank;
018
019 import java.io.Serializable;
020
021 import org.apache.commons.math3.exception.NullArgumentException;
022
023
024 /**
025 * Returns the median of the available values. This is the same as the 50th percentile.
026 * See {@link Percentile} for a description of the algorithm used.
027 * <p>
028 * <strong>Note that this implementation is not synchronized.</strong> If
029 * multiple threads access an instance of this class concurrently, and at least
030 * one of the threads invokes the <code>increment()</code> or
031 * <code>clear()</code> method, it must be synchronized externally.</p>
032 *
033 * @version $Id: Median.java 1416643 2012-12-03 19:37:14Z tn $
034 */
035 public class Median extends Percentile implements Serializable {
036
037 /** Serializable version identifier */
038 private static final long serialVersionUID = -3961477041290915687L;
039
040 /**
041 * Default constructor.
042 */
043 public Median() {
044 // No try-catch or advertised exception - arg is valid
045 super(50.0);
046 }
047
048 /**
049 * Copy constructor, creates a new {@code Median} identical
050 * to the {@code original}
051 *
052 * @param original the {@code Median} instance to copy
053 * @throws NullArgumentException if original is null
054 */
055 public Median(Median original) throws NullArgumentException {
056 super(original);
057 }
058
059 }