Byte class wraps a value of primitive type
* byte in an object. An object of type
* Byte contains a single field whose type is
* byte.
*
*
*
* In addition, this class provides several methods for converting a
*
* An exception of type In other words, this method returns a In other words, this method
* returns a
*
* The sequence of characters following an (optional) negative
* sign and/or radix specifier ("byte to a String and a String
* to a byte, as well as other constants and methods
* useful when dealing with a byte.
*
* @author Nakul Saraiya
* @version 1.40, 05/11/04
* @see java.lang.Number
* @since JDK1.1
*/
public final class Byte extends Number implements Comparablebyte can
* have, -27.
*/
public static final byte MIN_VALUE = -128;
/**
* A constant holding the maximum value a byte can
* have, 27-1.
*/
public static final byte MAX_VALUE = 127;
/**
* The Class instance representing the primitive type
* byte.
*/
public static final ClassString object representing the
* specified byte. The radix is assumed to be 10.
*
* @param b the byte to be converted
* @return the string representation of the specified 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 Byte instance representing the specified
* byte value.
* If a new 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 by caching
* frequently requested values.
*
* @param b a byte value.
* @return a Byte instance representing 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 decimal
* byte. The characters in the string must all be
* decimal digits, except that the first character may be an ASCII
* minus sign '-' ('\u002D') to
* indicate a negative value. The resulting 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 String containing the
* byte representation to be parsed
* @return the byte value represented by the
* argument in decimal
* @exception NumberFormatException if the string does not
* contain a parsable byte.
*/
public static byte parseByte(String s) throws NumberFormatException {
return parseByte(s, 10);
}
/**
* Parses the string argument as a signed 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 '-'
* ('\u002D') to indicate a negative value. The
* resulting byte value is returned.
* NumberFormatException is
* thrown if any of the following situations occurs:
*
*
*
* @param s the null or is a string of
* length zero.
*
* '-' ('\u002D') provided that the
* string is longer than length 1.
*
* byte.
* String containing the
* byte
* representation to be parsed
* @param radix the radix to be used while parsing s
* @return the byte value represented by the string
* argument in the specified radix
* @exception NumberFormatException If the string does
* not contain a parsable 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;
}
/**
* Returns a Byte object holding the value
* extracted from the specified String when parsed
* with the radix given by the second argument. The first argument
* is interpreted as representing a signed 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 Byte object that
* represents the byte value specified by the string.
* Byte object
* equal to the value of:
*
*
*
* @param s the string to be parsed
* @param radix the radix to be used in interpreting
* new Byte(Byte.parseByte(s, radix))
* s
* @return a Byte object holding the value
* represented by the string argument in the
* specified radix.
* @exception NumberFormatException If the String does
* not contain a parsable byte.
*/
public static Byte valueOf(String s, int radix)
throws NumberFormatException {
return new Byte(parseByte(s, radix));
}
/**
* Returns a Byte object holding the value
* given by the specified String. The argument is
* interpreted as representing a signed decimal byte,
* exactly as if the argument were given to the {@link
* #parseByte(java.lang.String)} method. The result is a
* Byte object that represents the byte
* value specified by the string. Byte object equal to the value of:
*
*
*
* @param s the string to be parsed
* @return a
* new Byte(Byte.parseByte(s))
* Byte object holding the value
* represented by the string argument
* @exception NumberFormatException If the String does
* not contain a parsable byte.
*/
public static Byte valueOf(String s) throws NumberFormatException {
return valueOf(s, 10);
}
/**
* Decodes a String into a Byte.
* Accepts decimal, hexadecimal, and octal numbers given by
* the following grammar:
*
*
*
*
* DecimalNumeral, HexDigits, and OctalDigits
* are defined in §3.10.1
* of the Java
* Language Specification.
*
*
* 0x HexDigits
* 0X HexDigits
* # HexDigits
* 0 OctalDigits
* -
* 0x",
* "0X", "#", or
* leading zero) is parsed as by the 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 String is the
* minus sign. No whitespace characters are permitted in the
* String.
*
* @param nm the String to decode.
* @return a Byte object holding the byte
* value represented by nm
* @exception NumberFormatException if the String does not
* contain a parsable byte.
* @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 Byte.
*
* @serial
*/
private final byte value;
/**
* Constructs a newly allocated Byte object that
* represents the specified byte value.
*
* @param value the value to be represented by the
* Byte.
*/
public Byte(byte value) {
this.value = value;
}
/**
* Constructs a newly allocated Byte object that
* represents the byte value indicated by the
* String parameter. The string is converted to a
* byte value in exactly the manner used by the
* parseByte method for radix 10.
*
* @param s the String to be converted to a
* Byte
* @exception NumberFormatException If the String
* does not contain a parsable 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 Byte as a
* byte.
*/
public byte byteValue() {
return value;
}
/**
* Returns the value of this Byte as a
* short.
*/
public short shortValue() {
return (short)value;
}
/**
* Returns the value of this Byte as an
* int.
*/
public int intValue() {
return (int)value;
}
/**
* Returns the value of this Byte as a
* long.
*/
public long longValue() {
return (long)value;
}
/**
* Returns the value of this Byte as a
* float.
*/
public float floatValue() {
return (float)value;
}
/**
* Returns the value of this Byte as a
* double.
*/
public double doubleValue() {
return (double)value;
}
/**
* Returns a String object representing this
* Byte's value. The value is converted to signed
* decimal representation and returned as a string, exactly as if
* the 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 Byte.
*/
public int hashCode() {
return (int)value;
}
/**
* Compares this object to the specified object. The result is
* true if and only if the argument is not
* null and is a Byte object that
* contains the same byte value as this object.
*
* @param obj the object to compare with
* @return true if the objects are the same;
* false otherwise.
*/
public boolean equals(Object obj) {
if (obj instanceof Byte) {
return value == ((Byte)obj).byteValue();
}
return false;
}
/**
* Compares two Byte objects numerically.
*
* @param anotherByte the Byte to be compared.
* @return the value 0 if this Byte is
* equal to the argument Byte; a value less than
* 0 if this Byte is numerically less
* than the argument Byte; and a value greater than
* 0 if this Byte is numerically
* greater than the argument Byte (signed
* comparison).
* @since 1.2
*/
public int compareTo(Byte anotherByte) {
return this.value - anotherByte.value;
}
/**
* The number of bits used to represent a 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;
}