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1   /*
2    * Copyright (c) 1994, 2011, 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  /**
29   * The abstract class {@code Number} is the superclass of platform
30   * classes representing numeric values that are convertible to the
31   * primitive types {@code byte}, {@code double}, {@code float}, {@code
32   * int}, {@code long}, and {@code short}.
33   *
34   * The specific semantics of the conversion from the numeric value of
35   * a particular {@code Number} implementation to a given primitive
36   * type is defined by the {@code Number} implementation in question.
37   *
38   * For platform classes, the conversion is often analogous to a
39   * narrowing primitive conversion or a widening primitive conversion
40   * as defining in <cite>The Java&trade; Language Specification</cite>
41   * for converting between primitive types.  Therefore, conversions may
42   * lose information about the overall magnitude of a numeric value, may
43   * lose precision, and may even return a result of a different sign
44   * than the input.
45   *
46   * See the documentation of a given {@code Number} implementation for
47   * conversion details.
48   *
49   * @author      Lee Boynton
50   * @author      Arthur van Hoff
51   * @jls 5.1.2 Widening Primitive Conversions
52   * @jls 5.1.3 Narrowing Primitive Conversions
53   * @since   JDK1.0
54   */
55  public abstract class Number implements java.io.Serializable {
56      /**
57       * Returns the value of the specified number as an {@code int},
58       * which may involve rounding or truncation.
59       *
60       * @return  the numeric value represented by this object after conversion
61       *          to type {@code int}.
62       */
63      public abstract int intValue();
64  
65      /**
66       * Returns the value of the specified number as a {@code long},
67       * which may involve rounding or truncation.
68       *
69       * @return  the numeric value represented by this object after conversion
70       *          to type {@code long}.
71       */
72      public abstract long longValue();
73  
74      /**
75       * Returns the value of the specified number as a {@code float},
76       * which may involve rounding.
77       *
78       * @return  the numeric value represented by this object after conversion
79       *          to type {@code float}.
80       */
81      public abstract float floatValue();
82  
83      /**
84       * Returns the value of the specified number as a {@code double},
85       * which may involve rounding.
86       *
87       * @return  the numeric value represented by this object after conversion
88       *          to type {@code double}.
89       */
90      public abstract double doubleValue();
91  
92      /**
93       * Returns the value of the specified number as a {@code byte},
94       * which may involve rounding or truncation.
95       *
96       * <p>This implementation returns the result of {@link #intValue} cast
97       * to a {@code byte}.
98       *
99       * @return  the numeric value represented by this object after conversion
100      *          to type {@code byte}.
101      * @since   JDK1.1
102      */
103     public byte byteValue() {
104         return (byte)intValue();
105     }
106 
107     /**
108      * Returns the value of the specified number as a {@code short},
109      * which may involve rounding or truncation.
110      *
111      * <p>This implementation returns the result of {@link #intValue} cast
112      * to a {@code short}.
113      *
114      * @return  the numeric value represented by this object after conversion
115      *          to type {@code short}.
116      * @since   JDK1.1
117      */
118     public short shortValue() {
119         return (short)intValue();
120     }
121 
122     /** use serialVersionUID from JDK 1.0.2 for interoperability */
123     private static final long serialVersionUID = -8742448824652078965L;
124 }