/* Byte.java -- object wrapper for byte Copyright (C) 1998, 2001, 2002, 2004, 2005 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath 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 for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version. */ package java.lang; /** * Instances of class Byte represent primitive byte * values. * * Additionally, this class provides various helper functions and variables * useful to bytes. * * @author Paul Fisher * @author John Keiser * @author Per Bothner * @author Eric Blake (ebb9@email.byu.edu) * @author Tom Tromey (tromey@redhat.com) * @author Andrew John Hughes (gnu_andrew@member.fsf.org) * @since 1.1 * @status updated to 1.5 */ public final class Byte extends Number implements Comparable { /** * Compatible with JDK 1.1+. */ private static final long serialVersionUID = -7183698231559129828L; /** * The minimum value a byte can represent is -128 (or * -27). */ public static final byte MIN_VALUE = -128; /** * The maximum value a byte can represent is 127 (or * 27 - 1). */ public static final byte MAX_VALUE = 127; /** * The primitive type byte is represented by this * Class object. */ public static final Class TYPE = (Class) VMClassLoader.getPrimitiveClass('B'); /** * The number of bits needed to represent a byte. * @since 1.5 */ public static final int SIZE = 8; // This caches Byte values, and is used by boxing conversions via // valueOf(). We're required to cache all possible values here. private static Byte[] byteCache = new Byte[MAX_VALUE - MIN_VALUE + 1]; static { for (int i=MIN_VALUE; i <= MAX_VALUE; i++) byteCache[i - MIN_VALUE] = new Byte((byte) i); } /** * The immutable value of this Byte. * * @serial the wrapped byte */ private final byte value; /** * Create a Byte object representing the value of the * byte argument. * * @param value the value to use */ public Byte(byte value) { this.value = value; } /** * Create a Byte object representing the value specified * by the String argument * * @param s the string to convert * @throws NumberFormatException if the String does not contain a byte * @see #valueOf(String) */ public Byte(String s) { value = parseByte(s, 10); } /** * Converts the byte to a String and assumes * a radix of 10. * * @param b the byte to convert to String * @return the String representation of the argument */ public static String toString(byte b) { return String.valueOf(b); } /** * Converts the specified String into a byte. * This function assumes a radix of 10. * * @param s the String to convert * @return the byte value of s * @throws NumberFormatException if s cannot be parsed as a * byte * @see #parseByte(String) */ public static byte parseByte(String s) { return parseByte(s, 10); } /** * Converts the specified String into an int * using the specified radix (base). The string must not be null * or empty. It may begin with an optional '-', which will negate the answer, * provided that there are also valid digits. Each digit is parsed as if by * Character.digit(d, radix), and must be in the range * 0 to radix - 1. Finally, the result must be * within MIN_VALUE to MAX_VALUE, inclusive. * Unlike Double.parseDouble, you may not have a leading '+'. * * @param s the String to convert * @param radix the radix (base) to use in the conversion * @return the String argument converted to byte * @throws NumberFormatException if s cannot be parsed as a * byte */ public static byte parseByte(String s, int radix) { int i = Integer.parseInt(s, radix, false); if ((byte) i != i) throw new NumberFormatException(); return (byte) i; } /** * Creates a new Byte object using the String * and specified radix (base). * * @param s the String to convert * @param radix the radix (base) to convert with * @return the new Byte * @throws NumberFormatException if s cannot be parsed as a * byte * @see #parseByte(String, int) */ public static Byte valueOf(String s, int radix) { return valueOf(parseByte(s, radix)); } /** * Creates a new Byte object using the String, * assuming a radix of 10. * * @param s the String to convert * @return the new Byte * @throws NumberFormatException if s cannot be parsed as a * byte * @see #Byte(String) * @see #parseByte(String) */ public static Byte valueOf(String s) { return valueOf(parseByte(s, 10)); } /** * Returns a Byte object wrapping the value. * In contrast to the Byte constructor, this method * will cache some values. It is used by boxing conversion. * * @param val the value to wrap * @return the Byte */ public static Byte valueOf(byte val) { return byteCache[val - MIN_VALUE]; } /** * Convert the specified String into a Byte. * The String may represent decimal, hexadecimal, or * octal numbers. * *

The extended BNF grammar is as follows:
*

   * DecodableString:
   *      ( [ - ] DecimalNumber )
   *    | ( [ - ] ( 0x | 0X
   *              | # ) { HexDigit }+ )
   *    | ( [ - ] 0 { OctalDigit } )
   * DecimalNumber:
   *        DecimalDigit except '0' { DecimalDigit }
   * DecimalDigit:
   *        Character.digit(d, 10) has value 0 to 9
   * OctalDigit:
   *        Character.digit(d, 8) has value 0 to 7
   * DecimalDigit:
   *        Character.digit(d, 16) has value 0 to 15
   * 
* Finally, the value must be in the range MIN_VALUE to * MAX_VALUE, or an exception is thrown. * * @param s the String to interpret * @return the value of the String as a Byte * @throws NumberFormatException if s cannot be parsed as a * byte * @throws NullPointerException if s is null * @see Integer#decode(String) */ public static Byte decode(String s) { int i = Integer.parseInt(s, 10, true); if ((byte) i != i) throw new NumberFormatException(); return valueOf((byte) i); } /** * Return the value of this Byte. * * @return the byte value */ public byte byteValue() { return value; } /** * Return the value of this Byte as a short. * * @return the short value */ public short shortValue() { return value; } /** * Return the value of this Byte as an int. * * @return the int value */ public int intValue() { return value; } /** * Return the value of this Byte as a long. * * @return the long value */ public long longValue() { return value; } /** * Return the value of this Byte as a float. * * @return the float value */ public float floatValue() { return value; } /** * Return the value of this Byte as a double. * * @return the double value */ public double doubleValue() { return value; } /** * Converts the Byte value to a String and * assumes a radix of 10. * * @return the String representation of this Byte * @see Integer#toString() */ public String toString() { return String.valueOf(value); } /** * Return a hashcode representing this Object. Byte's hash * code is simply its value. * * @return this Object's hash code */ public int hashCode() { return value; } /** * Returns true if obj is an instance of * Byte and represents the same byte value. * * @param obj the object to compare * @return whether these Objects are semantically equal */ public boolean equals(Object obj) { return obj instanceof Byte && value == ((Byte) obj).value; } /** * Compare two Bytes numerically by comparing their byte values. * The result is positive if the first is greater, negative if the second * is greater, and 0 if the two are equal. * * @param b the Byte to compare * @return the comparison * @since 1.2 */ public int compareTo(Byte b) { return value - b.value; } }