Chapter 10
The java.lang Package

Byte

Name

Byte

Synopsis

Class Name:

java.lang.Byte

Superclass:

java.lang.Number

Immediate Subclasses:

None

Interfaces Implemented:

None

Availability:

New as of JDK 1.1

The Byte class provides an object wrapper for a byte value. This is useful when you need to treat a byte value as an object. For example, there are a number of utility methods that take a reference to an Object as one of their arguments. You cannot specify a byte value for one of these arguments, but you can provide a reference to a Byte object that encapsulates the byte value. Furthermore, the Byte class is necessary as of JDK 1.1 to support the Reflection API and class literals.

The Byte class also provides a number of utility methods for converting byte values to other primitive types and for converting byte values to strings and vice versa.

Class Summary

public final class java.lang.Byte extends java.lang.Number {
  // Constants
  public static final byte MAX_VALUE;
  public static final byte MIN_VALUE;
  public static final Class TYPE;
  // Constructors
  public Byte(byte value);
  public Byte(String s);
  // Class Methods
  public static Byte decode(String nm);
  public static byte parseByte(String s);
  public static byte parseByte(String s, int radix);
  public static String toString(byte b);
  public static Byte valueOf(String s, int radix);
  public static Byte valueOf(String s);
  // Instance Methods
  public byte byteValue(); 
  public double doubleValue;
  public boolean equals(Object obj);
  public float floatValue
  public int hashCode();
  public int intValue();
  public long longValue();
  public short shortValue();
  public String toString();
}

Constants

MAX_VALUE

public static final byte MAX_VALUE= 127

The largest value that can be represented by a byte.

MIN_VALUE

public static final byte MIN_VALUE= -128

The smallest value that can be represented by a byte.

TYPE

public static final Class TYPE

The Class object that represents the primitive type byte. It is always true that Byte.TYPE == byte.class.

Constructors

Byte

public Byte(byte value)

Parameters

value: The byte value to be encapsulated by this object.

Description

Creates a Byte object with the specified byte value.

public Byte(String s) throws NumberFormatException

Parameters

s: The string to be made into a Byte object.

Throws

NumberFormatException: If the sequence of characters in the given String does not form a valid byte literal.

Description

Constructs a Byte object with the value specified by the given string. The string should consist of one or more digit characters. The digit characters can be preceded by a single `-' character. If the string contains any other characters, the constructor throws a NumberFormatException.

Class Methods

decode

public static Byte decode(String nm) throws NumberFormatException

Parameters

nm: A String representation of the value to be encapsulated by a Byte object. If the string begins with # or 0x, it is a radix 16 representation of the value. If the string begins with 0, it is a radix 8 representation of the value. Otherwise, it is assumed to be a radix 10 representation of the value.

Returns

A Byte object that encapsulates the given value.

Throws

NumberFormatException: If the String contains any non-digit characters other than a leading minus sign or the value represented by the String is less than Byte.MIN_VALUE or greater than Byte.MAX_VALUE.

Description

This method returns a Byte object that encapsulates the given value.

parseByte

public static byte parseByte(String s) throws NumberFormatException

Parameters

s: The String to be converted to a byte value.

Returns

The numeric value of the byte represented by the String object.

Throws

NumberFormatException: If the String does not contain a valid representation of a byte or the value represented by the String is less than Byte.MIN_VALUE or greater than Byte.MAX_VALUE.

Description

This method returns the numeric value of the byte represented by the contents of the given String object. The String must contain only decimal digits, except that the first character may be a minus sign.

 public static byte parseByte(String s, int radix) throws NumberFormatException

Parameters

s

The String to be converted to a byte value.

radix

The radix used in interpreting the characters in the String as digits. This value must be in the range Character.MIN_RADIX to Character.MAX_RADIX. If radix is in the range 2 through 10, only characters for which the Character.isDigit() method returns true are considered to be valid digits. If radix is in the range 11 through 36, characters in the ranges `A' through `Z' and `a' through `z' may be considered valid digits.

Returns

The numeric value of the byte represented by the String object in the specified radix.

Throws

NumberFormatException: If the String does not contain a valid representation of a byte, radix is not in the appropriate range, or the value represented by the String is less than Byte.MIN_VALUE or greater than Byte.MAX_VALUE.

Description

This method returns the numeric value of the byte represented by the contents of the given String object in the specified radix. The String must contain only valid digits of the specified radix, except that the first character may be a minus sign. The digits are parsed in the specified radix to produce the numeric value.

toString

public String toString(byte b)

Parameters

b: The byte value to be converted to a string.

Returns

The string representation of the given value.

Description

This method returns a String object that contains the decimal representation of the given value.

This method returns a string that begins with `-' if the given value is negative. The rest of the string is a sequence of one or more of the characters `0', `1', `2', `3', `4', `5', `6', `7', `8', and `9'. This method returns "0" if its argument is 0. Otherwise, the string returned by this method does not begin with "0" or "-0".

valueOf

public static Byte valueOf(String s) throws NumberFormatException

Parameters

s: The string to be made into a Byte object.

Returns

The Byte object constructed from the string.

Throws

NumberFormatException: If the String does not contain a valid representation of a byte or the value represented by the String is less than Byte.MIN_VALUE or greater than Byte.MAX_VALUE.

Description

 public static Byte valueOf(String s, int radix) throws NumberFormatException

Parameters

s

The string to be made into a Byte object.

radix

The radix used in converting the string to a value. This value must be in the range Character.MIN_RADIX to Character.MAX_RADIX.

Returns

The Byte object constructed from the string.

Throws

NumberFormatException: If the String does not contain a valid representation of a byte, radix is not in the appropriate range, or the value represented by the String is less than Byte.MIN_VALUE or greater than Byte.MAX_VALUE.

Description

Constructs a Byte object with the value specified by the given string in the specified radix. The string should consist of one or more digit characters or characters in the range `A' to `Z' or `a' to `z' that are considered digits in the given radix. The digit characters can be preceded by a single `-' character. If the string contains any other characters, the method throws a NumberFormatException.

Instance Methods

Method	Inherited From	Method	Inherited From
`clone()`	`Object`	`finalize()`	`Object`
`getClass()`	`Object`	`notify()`	`Object`
`notifyAll()`	`Object`	`wait()`	`Object`
`wait(long)`	`Object`	`wait(long, int)`	`Object`