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 */ Number()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 */ intValue()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 */ longValue()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 */ floatValue()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 */ doubleValue()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 */ byteValue()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 */ shortValue()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 } 127