1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 /*
19 * This is not the original file distributed by the Apache Software Foundation
20 * It has been modified by the Hipparchus project
21 */
22
23 package org.hipparchus.geometry.euclidean.twod;
24
25 import java.io.Serializable;
26
27 import org.hipparchus.geometry.Space;
28 import org.hipparchus.geometry.euclidean.oned.Euclidean1D;
29
30 /**
31 * This class implements a two-dimensional space.
32 */
33 public class Euclidean2D implements Serializable, Space {
34
35 /** Serializable version identifier. */
36 private static final long serialVersionUID = 4793432849757649566L;
37
38 /** Private constructor for the singleton.
39 */
40 private Euclidean2D() {
41 }
42
43 /** Get the unique instance.
44 * @return the unique instance
45 */
46 public static Euclidean2D getInstance() {
47 return LazyHolder.INSTANCE;
48 }
49
50 /** {@inheritDoc} */
51 @Override
52 public int getDimension() {
53 return 2;
54 }
55
56 /** {@inheritDoc} */
57 @Override
58 public Euclidean1D getSubSpace() {
59 return Euclidean1D.getInstance();
60 }
61
62 // CHECKSTYLE: stop HideUtilityClassConstructor
63 /** Holder for the instance.
64 * <p>We use here the Initialization On Demand Holder Idiom.</p>
65 */
66 private static class LazyHolder {
67 /** Cached field instance. */
68 private static final Euclidean2D INSTANCE = new Euclidean2D();
69 }
70 // CHECKSTYLE: resume HideUtilityClassConstructor
71
72 /** Handle deserialization of the singleton.
73 * @return the singleton instance
74 */
75 private Object readResolve() {
76 // return the singleton instance
77 return LazyHolder.INSTANCE;
78 }
79
80 }