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
018package org.apache.commons.math3.geometry.euclidean.twod;
019
020import java.io.Serializable;
021
022import org.apache.commons.math3.geometry.Space;
023import org.apache.commons.math3.geometry.euclidean.oned.Euclidean1D;
024
025/**
026 * This class implements a two-dimensional space.
027 * @version $Id: Euclidean2D.java 1562610 2014-01-29 22:17:16Z tn $
028 * @since 3.0
029 */
030public 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}