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      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  *      http://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 package org.apache.commons.math.util;
     19 
     20 import java.io.Serializable;
     21 
     22 import org.apache.commons.math.Field;
     23 
     24 /**
     25  * Representation of real numbers with arbitrary precision field.
     26  * <p>
     27  * This class is a singleton.
     28  * </p>
     29  * @see BigReal
     30  * @version $Revision: 811827 $ $Date: 2009-09-06 17:32:50 +0200 (dim. 06 sept. 2009) $
     31  * @since 2.0
     32  */
     33 public class BigRealField implements Field<BigReal>, Serializable  {
     34 
     35     /** Serializable version identifier */
     36     private static final long serialVersionUID = 4756431066541037559L;
     37 
     38     /** Private constructor for the singleton.
     39      */
     40     private BigRealField() {
     41     }
     42 
     43     /** Get the unique instance.
     44      * @return the unique instance
     45      */
     46     public static BigRealField getInstance() {
     47         return LazyHolder.INSTANCE;
     48     }
     49 
     50     /** {@inheritDoc} */
     51     public BigReal getOne() {
     52         return BigReal.ONE;
     53     }
     54 
     55     /** {@inheritDoc} */
     56     public BigReal getZero() {
     57         return BigReal.ZERO;
     58     }
     59 
     60     // CHECKSTYLE: stop HideUtilityClassConstructor
     61     /** Holder for the instance.
     62      * <p>We use here the Initialization On Demand Holder Idiom.</p>
     63      */
     64     private static class LazyHolder {
     65         /** Cached field instance. */
     66         private static final BigRealField INSTANCE = new BigRealField();
     67     }
     68     // CHECKSTYLE: resume HideUtilityClassConstructor
     69 
     70     /** Handle deserialization of the singleton.
     71      * @return the singleton instance
     72      */
     73     private Object readResolve() {
     74         // return the singleton instance
     75         return LazyHolder.INSTANCE;
     76     }
     77 
     78 }
     79