Home | History | Annotate | Download | only in lang 
      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 
     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 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  */
     55 public 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