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.fraction;
019
020 import java.io.Serializable;
021
022 import org.apache.commons.math3.Field;
023 import org.apache.commons.math3.FieldElement;
024
025 /**
026 * Representation of the fractional numbers field.
027 * <p>
028 * This class is a singleton.
029 * </p>
030 * @see Fraction
031 * @version $Id: FractionField.java 1416643 2012-12-03 19:37:14Z tn $
032 * @since 2.0
033 */
034 public class FractionField implements Field<Fraction>, Serializable {
035
036 /** Serializable version identifier */
037 private static final long serialVersionUID = -1257768487499119313L;
038
039 /** Private constructor for the singleton.
040 */
041 private FractionField() {
042 }
043
044 /** Get the unique instance.
045 * @return the unique instance
046 */
047 public static FractionField getInstance() {
048 return LazyHolder.INSTANCE;
049 }
050
051 /** {@inheritDoc} */
052 public Fraction getOne() {
053 return Fraction.ONE;
054 }
055
056 /** {@inheritDoc} */
057 public Fraction getZero() {
058 return Fraction.ZERO;
059 }
060
061 /** {@inheritDoc} */
062 public Class<? extends FieldElement<Fraction>> getRuntimeClass() {
063 return Fraction.class;
064 }
065 // CHECKSTYLE: stop HideUtilityClassConstructor
066 /** Holder for the instance.
067 * <p>We use here the Initialization On Demand Holder Idiom.</p>
068 */
069 private static class LazyHolder {
070 /** Cached field instance. */
071 private static final FractionField INSTANCE = new FractionField();
072 }
073 // CHECKSTYLE: resume HideUtilityClassConstructor
074
075 /** Handle deserialization of the singleton.
076 * @return the singleton instance
077 */
078 private Object readResolve() {
079 // return the singleton instance
080 return LazyHolder.INSTANCE;
081 }
082
083 }