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.fraction;
019
020import java.io.Serializable;
021
022import org.apache.commons.math3.Field;
023import 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 */
034public 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}