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 * <div class="preview-block">
49 * <div class="preview-comment">
50 * When preview features are enabled, {@code Number} is
51 * an abstract {@linkplain Class#isValue value class}.
52 * Subclasses of {@code Number} can be either an {@linkplain Class#isIdentity identity class}
53 * or a {@linkplain Class#isValue value class}.
54 * See {@jls The Java Language Specification 8.1.1.5 Value Classes}.
55 * </div>
56 * </div>
57 *
58 * @author Lee Boynton
59 * @author Arthur van Hoff
60 * @jls 5.1.2 Widening Primitive Conversion
61 * @jls 5.1.3 Narrowing Primitive Conversion
62 * @since 1.0
63 */
64 @jdk.internal.MigratedValueClass
65 public abstract class Number implements java.io.Serializable {
66 /**
67 * Constructor for subclasses to call.
68 */
69 public Number() {super();}
70
71 /**
72 * Returns the value of the specified number as an {@code int}.
73 *
74 * @return the numeric value represented by this object after conversion
75 * to type {@code int}.
76 */
77 public abstract int intValue();
78
79 /**
80 * Returns the value of the specified number as a {@code long}.
81 *
82 * @return the numeric value represented by this object after conversion
83 * to type {@code long}.
84 */
85 public abstract long longValue();
86
87 /**
88 * Returns the value of the specified number as a {@code float}.
89 *
90 * @return the numeric value represented by this object after conversion
91 * to type {@code float}.
92 */
93 public abstract float floatValue();
94
95 /**
96 * Returns the value of the specified number as a {@code double}.
97 *
98 * @return the numeric value represented by this object after conversion
99 * to type {@code double}.
100 */
101 public abstract double doubleValue();
102
103 /**
104 * Returns the value of the specified number as a {@code byte}.
105 *
106 * @implSpec
107 * The default implementation returns the result of {@link #intValue} cast
108 * to a {@code byte}.
109 *
110 * @return the numeric value represented by this object after conversion
111 * to type {@code byte}.
112 * @since 1.1
113 */
114 public byte byteValue() {
115 return (byte)intValue();
116 }
117
118 /**
119 * Returns the value of the specified number as a {@code short}.
120 *
121 * @implSpec
122 * The default implementation returns the result of {@link #intValue} cast
123 * to a {@code short}.
124 *
125 * @return the numeric value represented by this object after conversion
126 * to type {@code short}.
127 * @since 1.1
128 */
129 public short shortValue() {
130 return (short)intValue();
131 }
132
133 /** use serialVersionUID from JDK 1.0.2 for interoperability */
134 @java.io.Serial
135 private static final long serialVersionUID = -8742448824652078965L;
136 }