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
018 package org.apache.commons.math3.geometry.euclidean.twod;
019
020 import java.io.Serializable;
021
022 import org.apache.commons.math3.geometry.Space;
023 import org.apache.commons.math3.geometry.euclidean.oned.Euclidean1D;
024
025 /**
026 * This class implements a three-dimensional space.
027 * @version $Id: Euclidean2D.java 1416643 2012-12-03 19:37:14Z tn $
028 * @since 3.0
029 */
030 public class Euclidean2D implements Serializable, Space {
031
032 /** Serializable version identifier. */
033 private static final long serialVersionUID = 4793432849757649566L;
034
035 /** Private constructor for the singleton.
036 */
037 private Euclidean2D() {
038 }
039
040 /** Get the unique instance.
041 * @return the unique instance
042 */
043 public static Euclidean2D getInstance() {
044 return LazyHolder.INSTANCE;
045 }
046
047 /** {@inheritDoc} */
048 public int getDimension() {
049 return 2;
050 }
051
052 /** {@inheritDoc} */
053 public Euclidean1D getSubSpace() {
054 return Euclidean1D.getInstance();
055 }
056
057 // CHECKSTYLE: stop HideUtilityClassConstructor
058 /** Holder for the instance.
059 * <p>We use here the Initialization On Demand Holder Idiom.</p>
060 */
061 private static class LazyHolder {
062 /** Cached field instance. */
063 private static final Euclidean2D INSTANCE = new Euclidean2D();
064 }
065 // CHECKSTYLE: resume HideUtilityClassConstructor
066
067 /** Handle deserialization of the singleton.
068 * @return the singleton instance
069 */
070 private Object readResolve() {
071 // return the singleton instance
072 return LazyHolder.INSTANCE;
073 }
074
075 }