    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.util;
    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 real numbers with arbitrary precision field.
    027     * <p>
    028     * This class is a singleton.
    029     * </p>
    030     * @see BigReal
    031     * @version $Id: BigRealField.java 1416643 2012-12-03 19:37:14Z tn $
    032     * @since 2.0
    033     */
    034    public class BigRealField implements Field<BigReal>, Serializable  {
    035
    036        /** Serializable version identifier */
    037        private static final long serialVersionUID = 4756431066541037559L;
    038
    039        /** Private constructor for the singleton.
    040         */
    041        private BigRealField() {
    042        }
    043
    044        /** Get the unique instance.
    045         * @return the unique instance
    046         */
    047        public static BigRealField getInstance() {
    048            return LazyHolder.INSTANCE;
    049        }
    050
    051        /** {@inheritDoc} */
    052        public BigReal getOne() {
    053            return BigReal.ONE;
    054        }
    055
    056        /** {@inheritDoc} */
    057        public BigReal getZero() {
    058            return BigReal.ZERO;
    059        }
    060
    061        /** {@inheritDoc} */
    062        public Class<? extends FieldElement<BigReal>> getRuntimeClass() {
    063            return BigReal.class;
    064        }
    065
    066        // CHECKSTYLE: stop HideUtilityClassConstructor
    067        /** Holder for the instance.
    068         * <p>We use here the Initialization On Demand Holder Idiom.</p>
    069         */
    070        private static class LazyHolder {
    071            /** Cached field instance. */
    072            private static final BigRealField INSTANCE = new BigRealField();
    073        }
    074        // CHECKSTYLE: resume HideUtilityClassConstructor
    075
    076        /** Handle deserialization of the singleton.
    077         * @return the singleton instance
    078         */
    079        private Object readResolve() {
    080            // return the singleton instance
    081            return LazyHolder.INSTANCE;
    082        }
    083
    084    }