/* * Copyright 1996-2009 Sun Microsystems, Inc. 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. Sun designates this * particular file as subject to the "Classpath" exception as provided * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. */ package java.lang; /** * * The {@code Byte} class wraps a value of primitive type {@code byte} * in an object. An object of type {@code Byte} contains a single * field whose type is {@code byte}. * *

In addition, this class provides several methods for converting * a {@code byte} to a {@code String} and a {@code String} to a {@code * byte}, as well as other constants and methods useful when dealing * with a {@code byte}. * * @author Nakul Saraiya * @author Joseph D. Darcy * @see java.lang.Number * @since JDK1.1 */ public final class Byte extends Number implements Comparable { /** * A constant holding the minimum value a {@code byte} can * have, -27. */ public static final byte MIN_VALUE = -128; /** * A constant holding the maximum value a {@code byte} can * have, 27-1. */ public static final byte MAX_VALUE = 127; /** * The {@code Class} instance representing the primitive type * {@code byte}. */ public static final Class TYPE = (Class) Class.getPrimitiveClass("byte"); /** * Returns a new {@code String} object representing the * specified {@code byte}. The radix is assumed to be 10. * * @param b the {@code byte} to be converted * @return the string representation of the specified {@code byte} * @see java.lang.Integer#toString(int) */ public static String toString(byte b) { return Integer.toString((int)b, 10); } private static class ByteCache { private ByteCache(){} static final Byte cache[] = new Byte[-(-128) + 127 + 1]; static { for(int i = 0; i < cache.length; i++) cache[i] = new Byte((byte)(i - 128)); } } /** * Returns a {@code Byte} instance representing the specified * {@code byte} value. * If a new {@code Byte} instance is not required, this method * should generally be used in preference to the constructor * {@link #Byte(byte)}, as this method is likely to yield * significantly better space and time performance since * all byte values are cached. * * @param b a byte value. * @return a {@code Byte} instance representing {@code b}. * @since 1.5 */ public static Byte valueOf(byte b) { final int offset = 128; return ByteCache.cache[(int)b + offset]; } /** * Parses the string argument as a signed {@code byte} in the * radix specified by the second argument. The characters in the * string must all be digits, of the specified radix (as * determined by whether {@link java.lang.Character#digit(char, * int)} returns a nonnegative value) except that the first * character may be an ASCII minus sign {@code '-'} * ('\u002D') to indicate a negative value or an * ASCII plus sign {@code '+'} ('\u002B') to * indicate a positive value. The resulting {@code byte} value is * returned. * *

An exception of type {@code NumberFormatException} is * thrown if any of the following situations occurs: *

* * @param s the {@code String} containing the * {@code byte} * representation to be parsed * @param radix the radix to be used while parsing {@code s} * @return the {@code byte} value represented by the string * argument in the specified radix * @throws NumberFormatException If the string does * not contain a parsable {@code byte}. */ public static byte parseByte(String s, int radix) throws NumberFormatException { int i = Integer.parseInt(s, radix); if (i < MIN_VALUE || i > MAX_VALUE) throw new NumberFormatException( "Value out of range. Value:\"" + s + "\" Radix:" + radix); return (byte)i; } /** * Parses the string argument as a signed decimal {@code * byte}. The characters in the string must all be decimal digits, * except that the first character may be an ASCII minus sign * {@code '-'} ('\u002D') to indicate a negative * value or an ASCII plus sign {@code '+'} * ('\u002B') to indicate a positive value. The * resulting {@code byte} value is returned, exactly as if the * argument and the radix 10 were given as arguments to the {@link * #parseByte(java.lang.String, int)} method. * * @param s a {@code String} containing the * {@code byte} representation to be parsed * @return the {@code byte} value represented by the * argument in decimal * @throws NumberFormatException if the string does not * contain a parsable {@code byte}. */ public static byte parseByte(String s) throws NumberFormatException { return parseByte(s, 10); } /** * Returns a {@code Byte} object holding the value * extracted from the specified {@code String} when parsed * with the radix given by the second argument. The first argument * is interpreted as representing a signed {@code byte} in * the radix specified by the second argument, exactly as if the * argument were given to the {@link #parseByte(java.lang.String, * int)} method. The result is a {@code Byte} object that * represents the {@code byte} value specified by the string. * *

In other words, this method returns a {@code Byte} object * equal to the value of: * *

* {@code new Byte(Byte.parseByte(s, radix))} *
* * @param s the string to be parsed * @param radix the radix to be used in interpreting {@code s} * @return a {@code Byte} object holding the value * represented by the string argument in the * specified radix. * @throws NumberFormatException If the {@code String} does * not contain a parsable {@code byte}. */ public static Byte valueOf(String s, int radix) throws NumberFormatException { return new Byte(parseByte(s, radix)); } /** * Returns a {@code Byte} object holding the value * given by the specified {@code String}. The argument is * interpreted as representing a signed decimal {@code byte}, * exactly as if the argument were given to the {@link * #parseByte(java.lang.String)} method. The result is a * {@code Byte} object that represents the {@code byte} * value specified by the string. * *

In other words, this method returns a {@code Byte} object * equal to the value of: * *

* {@code new Byte(Byte.parseByte(s))} *
* * @param s the string to be parsed * @return a {@code Byte} object holding the value * represented by the string argument * @throws NumberFormatException If the {@code String} does * not contain a parsable {@code byte}. */ public static Byte valueOf(String s) throws NumberFormatException { return valueOf(s, 10); } /** * Decodes a {@code String} into a {@code Byte}. * Accepts decimal, hexadecimal, and octal numbers given by * the following grammar: * *
*
*
DecodableString: *
Signopt DecimalNumeral *
Signopt {@code 0x} HexDigits *
Signopt {@code 0X} HexDigits *
Signopt {@code #} HexDigits *
Signopt {@code 0} OctalDigits *

*

Sign: *
{@code -} *
{@code +} *
*
* * DecimalNumeral, HexDigits, and OctalDigits * are defined in §3.10.1 * of the Java * Language Specification. * *

The sequence of characters following an optional * sign and/or radix specifier ("{@code 0x}", "{@code 0X}", * "{@code #}", or leading zero) is parsed as by the {@code * Byte.parseByte} method with the indicated radix (10, 16, or 8). * This sequence of characters must represent a positive value or * a {@link NumberFormatException} will be thrown. The result is * negated if first character of the specified {@code String} is * the minus sign. No whitespace characters are permitted in the * {@code String}. * * @param nm the {@code String} to decode. * @return a {@code Byte} object holding the {@code byte} * value represented by {@code nm} * @throws NumberFormatException if the {@code String} does not * contain a parsable {@code byte}. * @see java.lang.Byte#parseByte(java.lang.String, int) */ public static Byte decode(String nm) throws NumberFormatException { int i = Integer.decode(nm); if (i < MIN_VALUE || i > MAX_VALUE) throw new NumberFormatException( "Value " + i + " out of range from input " + nm); return (byte)i; } /** * The value of the {@code Byte}. * * @serial */ private final byte value; /** * Constructs a newly allocated {@code Byte} object that * represents the specified {@code byte} value. * * @param value the value to be represented by the * {@code Byte}. */ public Byte(byte value) { this.value = value; } /** * Constructs a newly allocated {@code Byte} object that * represents the {@code byte} value indicated by the * {@code String} parameter. The string is converted to a * {@code byte} value in exactly the manner used by the * {@code parseByte} method for radix 10. * * @param s the {@code String} to be converted to a * {@code Byte} * @throws NumberFormatException If the {@code String} * does not contain a parsable {@code byte}. * @see java.lang.Byte#parseByte(java.lang.String, int) */ public Byte(String s) throws NumberFormatException { this.value = parseByte(s, 10); } /** * Returns the value of this {@code Byte} as a * {@code byte}. */ public byte byteValue() { return value; } /** * Returns the value of this {@code Byte} as a * {@code short}. */ public short shortValue() { return (short)value; } /** * Returns the value of this {@code Byte} as an * {@code int}. */ public int intValue() { return (int)value; } /** * Returns the value of this {@code Byte} as a * {@code long}. */ public long longValue() { return (long)value; } /** * Returns the value of this {@code Byte} as a * {@code float}. */ public float floatValue() { return (float)value; } /** * Returns the value of this {@code Byte} as a * {@code double}. */ public double doubleValue() { return (double)value; } /** * Returns a {@code String} object representing this * {@code Byte}'s value. The value is converted to signed * decimal representation and returned as a string, exactly as if * the {@code byte} value were given as an argument to the * {@link java.lang.Byte#toString(byte)} method. * * @return a string representation of the value of this object in * base 10. */ public String toString() { return String.valueOf((int)value); } /** * Returns a hash code for this {@code Byte}. */ public int hashCode() { return (int)value; } /** * Compares this object to the specified object. The result is * {@code true} if and only if the argument is not * {@code null} and is a {@code Byte} object that * contains the same {@code byte} value as this object. * * @param obj the object to compare with * @return {@code true} if the objects are the same; * {@code false} otherwise. */ public boolean equals(Object obj) { if (obj instanceof Byte) { return value == ((Byte)obj).byteValue(); } return false; } /** * Compares two {@code Byte} objects numerically. * * @param anotherByte the {@code Byte} to be compared. * @return the value {@code 0} if this {@code Byte} is * equal to the argument {@code Byte}; a value less than * {@code 0} if this {@code Byte} is numerically less * than the argument {@code Byte}; and a value greater than * {@code 0} if this {@code Byte} is numerically * greater than the argument {@code Byte} (signed * comparison). * @since 1.2 */ public int compareTo(Byte anotherByte) { return this.value - anotherByte.value; } /** * The number of bits used to represent a {@code byte} value in two's * complement binary form. * * @since 1.5 */ public static final int SIZE = 8; /** use serialVersionUID from JDK 1.1. for interoperability */ private static final long serialVersionUID = -7183698231559129828L; }