Java tutorial
/* * Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.lang; /** * The abstract class {@code Number} is the superclass of platform * classes representing numeric values that are convertible to the * primitive types {@code byte}, {@code double}, {@code float}, {@code * int}, {@code long}, and {@code short}. * * The specific semantics of the conversion from the numeric value of * a particular {@code Number} implementation to a given primitive * type is defined by the {@code Number} implementation in question. * * For platform classes, the conversion is often analogous to a * narrowing primitive conversion or a widening primitive conversion * as defined in <cite>The Java™ Language Specification</cite> * for converting between primitive types. Therefore, conversions may * lose information about the overall magnitude of a numeric value, may * lose precision, and may even return a result of a different sign * than the input. * * See the documentation of a given {@code Number} implementation for * conversion details. * * @author Lee Boynton * @author Arthur van Hoff * @jls 5.1.2 Widening Primitive Conversion * @jls 5.1.3 Narrowing Primitive Conversion * @since 1.0 */ public abstract class Number implements java.io.Serializable { /** * Constructor for subclasses to call. */ public Number() { super(); } /** * Returns the value of the specified number as an {@code int}. * * @return the numeric value represented by this object after conversion * to type {@code int}. */ public abstract int intValue(); /** * Returns the value of the specified number as a {@code long}. * * @return the numeric value represented by this object after conversion * to type {@code long}. */ public abstract long longValue(); /** * Returns the value of the specified number as a {@code float}. * * @return the numeric value represented by this object after conversion * to type {@code float}. */ public abstract float floatValue(); /** * Returns the value of the specified number as a {@code double}. * * @return the numeric value represented by this object after conversion * to type {@code double}. */ public abstract double doubleValue(); /** * Returns the value of the specified number as a {@code byte}. * * <p>This implementation returns the result of {@link #intValue} cast * to a {@code byte}. * * @return the numeric value represented by this object after conversion * to type {@code byte}. * @since 1.1 */ public byte byteValue() { return (byte) intValue(); } /** * Returns the value of the specified number as a {@code short}. * * <p>This implementation returns the result of {@link #intValue} cast * to a {@code short}. * * @return the numeric value represented by this object after conversion * to type {@code short}. * @since 1.1 */ public short shortValue() { return (short) intValue(); } /** use serialVersionUID from JDK 1.0.2 for interoperability */ private static final long serialVersionUID = -8742448824652078965L; }