[Chapter 12] Byte

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| Chapter 12 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

## Description

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

  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 method throws a `NumberFormatException`.

####

     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

### byteValue

#### public byte byteValue()

Returns

  The value of this object as a `byte`.

Overrides

  `Number.byteValue()`

Description

  This method returns the value of this object as a `byte`.

### doubleValue

#### public double doubleValue()

Returns

  The value of this object as a `double`.

Overrides

  `Number.doubleValue()`

Description

  This method returns the value of this object as a `double`.

### equals

#### public boolean equals(Object obj)

Parameters

  `obj`

    The object to be compared with this object.

Returns

  `true` if the objects are equal; `false` if they are not.

Overrides

  `Object.equals()`

Description

  This method returns `true` if `obj` is an instance of `Byte` and it contains the same value as the object this method is associated with.

### floatValue

#### public float floatValue()

Returns

  The value of this object as a `float`.

Overrides

  `Number.floatValue()`

Description

  This method returns the value of this object as a `float`.

### hashCode

#### public int hashCode()

Returns

  A hashcode based on the `byte` value of the object.

Overrides

  `Object.hashCode()`

Description

  This method returns a hashcode computed from the value of this object.

### intValue

#### public int intValue()

Returns

  The value of this object as an `int`.

Overrides

  `Number.intValue()`

Description

  This method returns the value of this object as an `int`.

### longValue

#### public long longValue()

Returns

  The value of this object as a `long`.

Overrides

  `Number.longValue()`

Description

  This method returns the value of this object as a `long`.

### shortValue

#### public short shortValue()

Returns

  The value of this object as a `short`.

Overrides

  `Number.shortValue()`

Description

  This method returns the value of this object as a `short`.

### toString

#### public String toString()

Returns

  The string representation of the value of this object.

Overrides

  `Object.toString()`

Description

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

  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".

## Inherited 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`

## See Also

`Character`, `Class`, `Double`, `Float`, `Integer`, `Long`, `Number`, `Short`, `String`

Boolean |  | Character