/*
* @(#)Byte.java 1.40 04/05/11
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.lang;
/**
*
* The <code>Byte</code> class wraps a value of primitive type
* <code>byte</code> in an object. An object of type
* <code>Byte</code> contains a single field whose type is
* <code>byte</code>.
*
* <p>
*
* In addition, this class provides several methods for converting a
* <code>byte</code> to a <code>String</code> and a <code>String</code>
* to a <code>byte</code>, as well as other constants and methods
* useful when dealing with a <code>byte</code>.
*
* @author Nakul Saraiya
* @version 1.40, 05/11/04
* @see java.lang.Number
* @since JDK1.1
*/
public final class Byte extends Number implements Comparable<Byte> {
/**
* A constant holding the minimum value a <code>byte</code> can
* have, -2<sup>7</sup>.
*/
public static final byte MIN_VALUE = -128;
/**
* A constant holding the maximum value a <code>byte</code> can
* have, 2<sup>7</sup>-1.
*/
public static final byte MAX_VALUE = 127;
/**
* The <code>Class</code> instance representing the primitive type
* <code>byte</code>.
*/
public static final Class<Byte> TYPE = (Class<Byte>) Class.getPrimitiveClass("byte");
/**
* Returns a new <code>String</code> object representing the
* specified <code>byte</code>. The radix is assumed to be 10.
*
* @param b the <code>byte</code> to be converted
* @return the string representation of the specified <code>byte</code>
* @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 <tt>Byte</tt> instance representing the specified
* <tt>byte</tt> value.
* If a new <tt>Byte</tt> 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 by caching
* frequently requested values.
*
* @param b a byte value.
* @return a <tt>Byte</tt> instance representing <tt>b</tt>.
* @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 decimal
* <code>byte</code>. The characters in the string must all be
* decimal digits, except that the first character may be an ASCII
* minus sign <code>'-'</code> (<code>'\u002D'</code>) to
* indicate a negative value. The resulting <code>byte</code> 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</code> containing the
* <code>byte</code> representation to be parsed
* @return the <code>byte</code> value represented by the
* argument in decimal
* @exception NumberFormatException if the string does not
* contain a parsable <code>byte</code>.
*/
public static byte parseByte(String s) throws NumberFormatException {
return parseByte(s, 10);
}
/**
* Parses the string argument as a signed <code>byte</code> 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>'-'</code>
* (<code>'\u002D'</code>) to indicate a negative value. The
* resulting <code>byte</code> value is returned.
* <p>
* An exception of type <code>NumberFormatException</code> is
* thrown if any of the following situations occurs:
* <ul>
* <li> The first argument is <code>null</code> or is a string of
* length zero.
*
* <li> The radix is either smaller than {@link
* java.lang.Character#MIN_RADIX} or larger than {@link
* java.lang.Character#MAX_RADIX}.
*
* <li> Any character of the string is not a digit of the specified
* radix, except that the first character may be a minus sign
* <code>'-'</code> (<code>'\u002D'</code>) provided that the
* string is longer than length 1.
*
* <li> The value represented by the string is not a value of type
* <code>byte</code>.
* </ul>
*
* @param s the <code>String</code> containing the
* <code>byte</code>
* representation to be parsed
* @param radix the radix to be used while parsing <code>s</code>
* @return the <code>byte</code> value represented by the string
* argument in the specified radix
* @exception NumberFormatException If the string does
* not contain a parsable <code>byte</code>.
*/
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;
}
/**
* Returns a <code>Byte</code> object holding the value
* extracted from the specified <code>String</code> when parsed
* with the radix given by the second argument. The first argument
* is interpreted as representing a signed <code>byte</code> 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</code> object that
* represents the <code>byte</code> value specified by the string.
* <p> In other words, this method returns a <code>Byte</code> object
* equal to the value of:
*
* <blockquote><code>
* new Byte(Byte.parseByte(s, radix))
* </code></blockquote>
*
* @param s the string to be parsed
* @param radix the radix to be used in interpreting <code>s</code>
* @return a <code>Byte</code> object holding the value
* represented by the string argument in the
* specified radix.
* @exception NumberFormatException If the <code>String</code> does
* not contain a parsable <code>byte</code>.
*/
public static Byte valueOf(String s, int radix)
throws NumberFormatException {
return new Byte(parseByte(s, radix));
}
/**
* Returns a <code>Byte</code> object holding the value
* given by the specified <code>String</code>. The argument is
* interpreted as representing a signed decimal <code>byte</code>,
* exactly as if the argument were given to the {@link
* #parseByte(java.lang.String)} method. The result is a
* <code>Byte</code> object that represents the <code>byte</code>
* value specified by the string. <p> In other words, this method
* returns a <code>Byte</code> object equal to the value of:
*
* <blockquote><code>
* new Byte(Byte.parseByte(s))
* </code></blockquote>
*
* @param s the string to be parsed
* @return a <code>Byte</code> object holding the value
* represented by the string argument
* @exception NumberFormatException If the <code>String</code> does
* not contain a parsable <code>byte</code>.
*/
public static Byte valueOf(String s) throws NumberFormatException {
return valueOf(s, 10);
}
/**
* Decodes a <code>String</code> into a <code>Byte</code>.
* Accepts decimal, hexadecimal, and octal numbers given by
* the following grammar:
*
* <blockquote>
* <dl>
* <dt><i>DecodableString:</i>
* <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
* <dd><i>Sign<sub>opt</sub></i> <code>0x</code> <i>HexDigits</i>
* <dd><i>Sign<sub>opt</sub></i> <code>0X</code> <i>HexDigits</i>
* <dd><i>Sign<sub>opt</sub></i> <code>#</code> <i>HexDigits</i>
* <dd><i>Sign<sub>opt</sub></i> <code>0</code> <i>OctalDigits</i>
* <p>
* <dt><i>Sign:</i>
* <dd><code>-</code>
* </dl>
* </blockquote>
*
* <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
* are defined in <a href="http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#48282">§3.10.1</a>
* of the <a href="http://java.sun.com/docs/books/jls/html/">Java
* Language Specification</a>.
* <p>
* The sequence of characters following an (optional) negative
* sign and/or radix specifier ("<code>0x</code>",
* "<code>0X</code>", "<code>#</code>", or
* leading zero) is parsed as by the <code>Byte.parseByte</code>
* 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</code> is the
* minus sign. No whitespace characters are permitted in the
* <code>String</code>.
*
* @param nm the <code>String</code> to decode.
* @return a <code>Byte</code> object holding the <code>byte</code>
* value represented by <code>nm</code>
* @exception NumberFormatException if the <code>String</code> does not
* contain a parsable <code>byte</code>.
* @see java.lang.Byte#parseByte(java.lang.String, int)
*/
public static Byte decode(String nm) throws NumberFormatException {
int radix = 10;
int index = 0;
boolean negative = false;
Byte result;
// Handle minus sign, if present
if (nm.startsWith("-")) {
negative = true;
index++;
}
if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
index += 2;
radix = 16;
} else if (nm.startsWith("#", index)) {
index++;
radix = 16;
} else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
index++;
radix = 8;
}
if (nm.startsWith("-", index))
throw new NumberFormatException("Negative sign in wrong position");
try {
result = Byte.valueOf(nm.substring(index), radix);
result = negative ? new Byte((byte)-result.byteValue()) : result;
} catch (NumberFormatException e) {
// If number is Byte.MIN_VALUE, we'll end up here. The next line
// handles this case, and causes any genuine format error to be
// rethrown.
String constant = negative ? new String("-" + nm.substring(index))
: nm.substring(index);
result = Byte.valueOf(constant, radix);
}
return result;
}
/**
* The value of the <code>Byte</code>.
*
* @serial
*/
private final byte value;
/**
* Constructs a newly allocated <code>Byte</code> object that
* represents the specified <code>byte</code> value.
*
* @param value the value to be represented by the
* <code>Byte</code>.
*/
public Byte(byte value) {
this.value = value;
}
/**
* Constructs a newly allocated <code>Byte</code> object that
* represents the <code>byte</code> value indicated by the
* <code>String</code> parameter. The string is converted to a
* <code>byte</code> value in exactly the manner used by the
* <code>parseByte</code> method for radix 10.
*
* @param s the <code>String</code> to be converted to a
* <code>Byte</code>
* @exception NumberFormatException If the <code>String</code>
* does not contain a parsable <code>byte</code>.
* @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</code> as a
* <code>byte</code>.
*/
public byte byteValue() {
return value;
}
/**
* Returns the value of this <code>Byte</code> as a
* <code>short</code>.
*/
public short shortValue() {
return (short)value;
}
/**
* Returns the value of this <code>Byte</code> as an
* <code>int</code>.
*/
public int intValue() {
return (int)value;
}
/**
* Returns the value of this <code>Byte</code> as a
* <code>long</code>.
*/
public long longValue() {
return (long)value;
}
/**
* Returns the value of this <code>Byte</code> as a
* <code>float</code>.
*/
public float floatValue() {
return (float)value;
}
/**
* Returns the value of this <code>Byte</code> as a
* <code>double</code>.
*/
public double doubleValue() {
return (double)value;
}
/**
* Returns a <code>String</code> object representing this
* <code>Byte</code>'s value. The value is converted to signed
* decimal representation and returned as a string, exactly as if
* the <code>byte</code> 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</code>.
*/
public int hashCode() {
return (int)value;
}
/**
* Compares this object to the specified object. The result is
* <code>true</code> if and only if the argument is not
* <code>null</code> and is a <code>Byte</code> object that
* contains the same <code>byte</code> value as this object.
*
* @param obj the object to compare with
* @return <code>true</code> if the objects are the same;
* <code>false</code> otherwise.
*/
public boolean equals(Object obj) {
if (obj instanceof Byte) {
return value == ((Byte)obj).byteValue();
}
return false;
}
/**
* Compares two <code>Byte</code> objects numerically.
*
* @param anotherByte the <code>Byte</code> to be compared.
* @return the value <code>0</code> if this <code>Byte</code> is
* equal to the argument <code>Byte</code>; a value less than
* <code>0</code> if this <code>Byte</code> is numerically less
* than the argument <code>Byte</code>; and a value greater than
* <code>0</code> if this <code>Byte</code> is numerically
* greater than the argument <code>Byte</code> (signed
* comparison).
* @since 1.2
*/
public int compareTo(Byte anotherByte) {
return this.value - anotherByte.value;
}
/**
* The number of bits used to represent a <tt>byte</tt> 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;
}
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