1 /*
  2  * Copyright (c) 1994, 2021, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.  Oracle designates this
  8  * particular file as subject to the "Classpath" exception as provided
  9  * by Oracle in the LICENSE file that accompanied this code.
 10  *
 11  * This code is distributed in the hope that it will be useful, but WITHOUT
 12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 14  * version 2 for more details (a copy is included in the LICENSE file that
 15  * accompanied this code).
 16  *
 17  * You should have received a copy of the GNU General Public License version
 18  * 2 along with this work; if not, write to the Free Software Foundation,
 19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 20  *
 21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 22  * or visit www.oracle.com if you need additional information or have any
 23  * questions.
 24  */
 25 
 26 package java.lang;

 27 /**
 28  * The abstract class {@code Number} is the superclass of platform
 29  * classes representing numeric values that are convertible to the
 30  * primitive types {@code byte}, {@code double}, {@code float}, {@code
 31  * int}, {@code long}, and {@code short}.
 32  *
 33  * The specific semantics of the conversion from the numeric value of
 34  * a particular {@code Number} implementation to a given primitive
 35  * type is defined by the {@code Number} implementation in question.
 36  *
 37  * For platform classes, the conversion is often analogous to a
 38  * narrowing primitive conversion or a widening primitive conversion
 39  * as defined in <cite>The Java Language Specification</cite>
 40  * for converting between primitive types.  Therefore, conversions may
 41  * lose information about the overall magnitude of a numeric value, may
 42  * lose precision, and may even return a result of a different sign
 43  * than the input.
 44  *
 45  * See the documentation of a given {@code Number} implementation for
 46  * conversion details.
 47  *
 48  * @author      Lee Boynton
 49  * @author      Arthur van Hoff
 50  * @jls 5.1.2 Widening Primitive Conversion
 51  * @jls 5.1.3 Narrowing Primitive Conversion
 52  * @since   1.0
 53  */
 54 @jdk.internal.MigratedValueClass
 55 public abstract class Number implements java.io.Serializable {
 56     /**
 57      * Constructor for subclasses to call.
 58      */
 59     public Number() {super();}
 60 
 61     /**
 62      * Returns the value of the specified number as an {@code int}.
 63      *
 64      * @return  the numeric value represented by this object after conversion
 65      *          to type {@code int}.
 66      */
 67     public abstract int intValue();
 68 
 69     /**
 70      * Returns the value of the specified number as a {@code long}.
 71      *
 72      * @return  the numeric value represented by this object after conversion
 73      *          to type {@code long}.
 74      */
 75     public abstract long longValue();
 76 
 77     /**
 78      * Returns the value of the specified number as a {@code float}.
 79      *
 80      * @return  the numeric value represented by this object after conversion
 81      *          to type {@code float}.
 82      */
 83     public abstract float floatValue();
 84 
 85     /**
 86      * Returns the value of the specified number as a {@code double}.
 87      *
 88      * @return  the numeric value represented by this object after conversion
 89      *          to type {@code double}.
 90      */
 91     public abstract double doubleValue();
 92 
 93     /**
 94      * Returns the value of the specified number as a {@code byte}.
 95      *
 96      * @implSpec
 97      * The default implementation returns the result of {@link #intValue} cast
 98      * to a {@code byte}.
 99      *
100      * @return  the numeric value represented by this object after conversion
101      *          to type {@code byte}.
102      * @since   1.1
103      */
104     public byte byteValue() {
105         return (byte)intValue();
106     }
107 
108     /**
109      * Returns the value of the specified number as a {@code short}.
110      *
111      * @implSpec
112      * The default implementation returns the result of {@link #intValue} cast
113      * to a {@code short}.
114      *
115      * @return  the numeric value represented by this object after conversion
116      *          to type {@code short}.
117      * @since   1.1
118      */
119     public short shortValue() {
120         return (short)intValue();
121     }
122 
123     /** use serialVersionUID from JDK 1.0.2 for interoperability */
124     @java.io.Serial
125     private static final long serialVersionUID = -8742448824652078965L;
126 }
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