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
26package 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 */
55public 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}
125