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 /**
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 defined in <cite>The Java 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 Conversion
52 * @jls 5.1.3 Narrowing Primitive Conversion
53 * @since 1.0
54 */
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 }