Byte (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

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Standard Ed. 6

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java.lang
Class Byte

java.lang.Object
  java.lang.Number
      java.lang.Byte

All Implemented Interfaces:: Serializable, Comparable<Byte>

public final class Byte
extends Number
implements Comparable<Byte>
extends Number
implements Comparable<Byte>

The 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 byte to a String and a String to a byte, as well as other constants and methods useful when dealing with a byte.

Since:: JDK1.1
See Also:: Number, Serialized Form

Field Summary

static byte MAX_VALUE
          A constant holding the maximum value a byte can have, 2⁷-1.

static byte MIN_VALUE
          A constant holding the minimum value a byte can have, -2⁷.

static int SIZE
          The number of bits used to represent a byte value in two's complement binary form.

static Class<Byte> TYPE
          The Class instance representing the primitive type byte.

Constructor Summary

Byte(byte value)
          Constructs a newly allocated Byte object that represents the specified byte value.

Byte(String s)
          Constructs a newly allocated Byte object that represents the byte value indicated by the String parameter.

Method Summary

byte byteValue()
          Returns the value of this Byte as a byte.

int compareTo(Byte anotherByte)
          Compares two Byte objects numerically.

static Byte decode(String nm)
          Decodes a String into a Byte.

double doubleValue()
          Returns the value of this Byte as a double.

boolean equals(Object obj)
          Compares this object to the specified object.

float floatValue()
          Returns the value of this Byte as a float.

int hashCode()
          Returns a hash code for this Byte.

int intValue()
          Returns the value of this Byte as an int.

long longValue()
          Returns the value of this Byte as a long.

static byte parseByte(String s)
          Parses the string argument as a signed decimal byte.

static byte parseByte(String s, int radix)
          Parses the string argument as a signed byte in the radix specified by the second argument.

short shortValue()
          Returns the value of this Byte as a short.

String toString()
          Returns a String object representing this Byte's value.

static String toString(byte b)
          Returns a new String object representing the specified byte.

static Byte valueOf(byte b)
          Returns a Byte instance representing the specified byte value.

static Byte valueOf(String s)
          Returns a Byte object holding the value given by the specified String.

static Byte valueOf(String s, int radix)
          Returns a Byte object holding the value extracted from the specified String when parsed with the radix given by the second argument.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Summary
`static byte`	`MAX_VALUE` A constant holding the maximum value a `byte` can have, 2⁷-1.
`static byte`	`MIN_VALUE` A constant holding the minimum value a `byte` can have, -2⁷.
`static int`	`SIZE` The number of bits used to represent a `byte` value in two's complement binary form.
`static Class<Byte>`	`TYPE` The `Class` instance representing the primitive type `byte`.

Constructor Summary
`Byte(byte value)` Constructs a newly allocated `Byte` object that represents the specified `byte` value.
`Byte(String s)` Constructs a newly allocated `Byte` object that represents the `byte` value indicated by the `String` parameter.

Method Summary
`byte`	`byteValue()` Returns the value of this `Byte` as a `byte`.
`int`	`compareTo(Byte anotherByte)` Compares two `Byte` objects numerically.
`static Byte`	`decode(String nm)` Decodes a `String` into a `Byte`.
`double`	`doubleValue()` Returns the value of this `Byte` as a `double`.
`boolean`	`equals(Object obj)` Compares this object to the specified object.
`float`	`floatValue()` Returns the value of this `Byte` as a `float`.
`int`	`hashCode()` Returns a hash code for this `Byte`.
`int`	`intValue()` Returns the value of this `Byte` as an `int`.
`long`	`longValue()` Returns the value of this `Byte` as a `long`.
`static byte`	`parseByte(String s)` Parses the string argument as a signed decimal `byte`.
`static byte`	`parseByte(String s, int radix)` Parses the string argument as a signed `byte` in the radix specified by the second argument.
`short`	`shortValue()` Returns the value of this `Byte` as a `short`.
`String`	`toString()` Returns a `String` object representing this `Byte`'s value.
`static String`	`toString(byte b)` Returns a new `String` object representing the specified `byte`.
`static Byte`	`valueOf(byte b)` Returns a `Byte` instance representing the specified `byte` value.
`static Byte`	`valueOf(String s)` Returns a `Byte` object holding the value given by the specified `String`.
`static Byte`	`valueOf(String s, int radix)` Returns a `Byte` object holding the value extracted from the specified `String` when parsed with the radix given by the second argument.

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

Field Detail

MIN_VALUE

public static final byte MIN_VALUE

A constant holding the minimum value a byte can have, -2⁷.

See Also:: Constant Field Values

MAX_VALUE

public static final byte MAX_VALUE

A constant holding the maximum value a byte can have, 2⁷-1.

See Also:: Constant Field Values

TYPE

public static final Class<Byte> TYPE

The Class instance representing the primitive type byte.

SIZE

public static final int SIZE

The number of bits used to represent a byte value in two's complement binary form.

Since:: 1.5
See Also:: Constant Field Values

Constructor Detail

Byte

public Byte(byte value)

Constructs a newly allocated Byte object that represents the specified byte value.

Parameters:: value - the value to be represented by the Byte.

Byte

public Byte(String s)
     throws NumberFormatException

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.

Parameters:: s - the String to be converted to a Byte
Throws:: NumberFormatException - If the String does not contain a parsable byte.
See Also:: parseByte(java.lang.String, int)

Method Detail

toString

public static String toString(byte b)

Returns a new String object representing the specified byte. The radix is assumed to be 10.

Parameters:: b - the byte to be converted
Returns:: the string representation of the specified byte
See Also:: Integer.toString(int)

valueOf

public static Byte valueOf(byte b)

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 Byte(byte), as this method is likely to yield significantly better space and time performance by caching frequently requested values.

Parameters:: b - a byte value.
Returns:: a Byte instance representing b.
Since:: 1.5

parseByte

public static byte parseByte(String s)
                      throws NumberFormatException

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

parseByte(java.lang.String,
 int)

method.

Parameters:: s - a String containing the byte representation to be parsed
Returns:: the byte value represented by the argument in decimal
Throws:: NumberFormatException - if the string does not contain a parsable byte.

parseByte

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

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

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.

An exception of type NumberFormatException is thrown if any of the following situations occurs:

The first argument is null or is a string of length zero.
The radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.
Any character of the string is not a digit of the specified radix, except that the first character may be a minus sign '-' ('\u002D') provided that the string is longer than length 1.
The value represented by the string is not a value of type byte.

Parameters:: s - the String containing the byte representation to be parsed; radix - the radix to be used while parsing s
Returns:: the byte value represented by the string argument in the specified radix
Throws:: NumberFormatException - If the string does not contain a parsable byte.

valueOf

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

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

parseByte(java.lang.String,
 int)

method. The result is a Byte object that represents the byte value specified by the string.

In other words, this method returns a Byte object equal to the value of:

new Byte(Byte.parseByte(s, radix))

Parameters:: s - the string to be parsed; radix - the radix to be used in interpreting s
Returns:: a Byte object holding the value represented by the string argument in the specified radix.
Throws:: NumberFormatException - If the String does not contain a parsable byte.

valueOf

public static Byte valueOf(String s)
                    throws NumberFormatException

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 parseByte(java.lang.String) method. The result is a Byte object that represents the byte value specified by the string.

In other words, this method returns a Byte object equal to the value of:

new Byte(Byte.parseByte(s))

Parameters:: s - the string to be parsed
Returns:: a Byte object holding the value represented by the string argument
Throws:: NumberFormatException - If the String does not contain a parsable byte.

decode

public static Byte decode(String nm)
                   throws NumberFormatException

Decodes a String into a Byte. Accepts decimal, hexadecimal, and octal numbers given by the following grammar:

DecodableString:
Sign_opt DecimalNumeral
Sign_opt 0x HexDigits
Sign_opt 0X HexDigits
Sign_opt # HexDigits
Sign_opt 0 OctalDigits

Sign:
-

DecimalNumeral, HexDigits, and OctalDigits are defined in §3.10.1 of the Java Language Specification.

The sequence of characters following an (optional) negative sign and/or radix specifier ("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 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.

Parameters:: nm - the String to decode.
Returns:: a Byte object holding the byte value represented by nm
Throws:: NumberFormatException - if the String does not contain a parsable byte.
See Also:: parseByte(java.lang.String, int)

byteValue

public byte byteValue()

Returns the value of this Byte as a byte.

Overrides:: byteValue in class Number

Returns:: the numeric value represented by this object after conversion to type byte.

shortValue

public short shortValue()

Returns the value of this Byte as a short.

Overrides:: shortValue in class Number

Returns:: the numeric value represented by this object after conversion to type short.

intValue

public int intValue()

Returns the value of this Byte as an int.

Specified by:: intValue in class Number

Returns:: the numeric value represented by this object after conversion to type int.

longValue

public long longValue()

Returns the value of this Byte as a long.

Specified by:: longValue in class Number

Returns:: the numeric value represented by this object after conversion to type long.

floatValue

public float floatValue()

Returns the value of this Byte as a float.

Specified by:: floatValue in class Number

Returns:: the numeric value represented by this object after conversion to type float.

doubleValue

public double doubleValue()

Returns the value of this Byte as a double.

Specified by:: doubleValue in class Number

Returns:: the numeric value represented by this object after conversion to type double.

toString

public String toString()

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 toString(byte) method.

Overrides:: toString in class Object

Returns:: a string representation of the value of this object in base 10.

hashCode

public int hashCode()

Returns a hash code for this Byte.

Overrides:: hashCode in class Object

Returns:: a hash code value for this object.
See Also:: Object.equals(java.lang.Object), Hashtable

equals

public boolean equals(Object obj)

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.

Overrides:: equals in class Object

Parameters:: obj - the object to compare with
Returns:: true if the objects are the same; false otherwise.
See Also:: Object.hashCode(), Hashtable

compareTo

public int compareTo(Byte anotherByte)

Compares two Byte objects numerically.

Specified by:: compareTo in interface Comparable<Byte>

Parameters:: anotherByte - the Byte to be compared.
Returns:: 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

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Submit a bug or feature
For further API reference and developer documentation, see Java SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Byte (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

java.lang Class Byte

MIN_VALUE

MAX_VALUE

TYPE

SIZE

Byte

Byte

toString

valueOf

parseByte

parseByte

valueOf

valueOf

decode

byteValue

shortValue

intValue

longValue

floatValue

doubleValue

toString

hashCode

equals

compareTo

java.lang
Class Byte