[Chapter 12] Long

#

| Chapter 12 The java.lang Package |

# Long

## Name

Long

## Synopsis

Class Name:

  `java.lang.Long`

Superclass:

  `java.lang.Number`

Immediate Subclasses:

  None

Interfaces Implemented:

  None

Availability:

  JDK 1.0 or later

## Description

The `Long` class provides an object wrapper for a `long` value. This is useful when you need to treat a `long` 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 `long` value for one of these arguments, but you can provide a reference to a `Long` object that encapsulates the `long` value. Furthermore, as of JDK 1.1, the `Long` class is necessary to support the Reflection API and class literals.

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

## Class Summary

    public final class java.lang.Long extends java.lang.Number {
        // Constants
        public static final long MIN_VALUE;
        public static final long MAX_VALUE;
        public final static Class TYPE;                    // New in 1.1
        // Constructors
        public Long(long value);
        public Long(String s);
        // Class Methods
        public static Long getLong(String nm);
        public static Long getLong(String nm, long val);
        public static Long getLong(String nm, Long val);
        public static long parseLong(String s);
        public static long parseLong(String s, int radix);
        public static String toBinaryString(long i);
        public static String toHexString(long i);
        public static String toOctalString(long i);
        public static String toString(long i);
        public static String toString(long i, int radix);
        public static Long valueOf(String s);
        public static Long valueOf(String s, int radix);
        // Instance Methods
        public byte byteValue();                           // New in 1.1
        public double doubleValue();
        public boolean equals(Object obj);
        public float floatValue();
        public int hashCode();
        public int intValue();
        public long longValue();
        public short shortValue();                         // New in 1.1
        public String toString();
    }

## Constants

### MAX_VALUE

#### `public static final long MAX_VALUE = 0x7fffffffffffffffL`

Description

  The largest value that can be represented by a `long`.

### MIN_VALUE

#### `public static final long MIN_VALUE = 0x8000000000000000L`

Description

  The smallest value that can be represented by a `long`.

### TYPE

#### `public static final Class TYPE`

Availability

  New as of JDK 1.1

Description

  The `Class` object that represents the type `long`. It is always true that `Long.TYPE` `==` `long.class`.

## Constructors

### Long

#### `public Long(long value)`

Parameters

  `value`

    The `long` value to be encapsulated by this object.

Description

  Creates a `Long` object with the specified `long` value.

#### `public Long(String s) throws NumberFormatException`

Parameters

  `s`

    The string to be made into a `Long` object.

Throws

  `NumberFormatException`

    If the sequence of characters in the given `String` does not form a valid `long` literal.

Description

  Constructs a `Long` 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

### getLong

#### `public static Integer getLong(String nm)`

Parameters

  `nm`

    The name of a system property.

Returns

  The value of the system property as a `Long` object or a `Long` object with the value 0 if the named property does not exist or cannot be parsed.

Description

  This method retrieves the value of the named system property and returns it as a `Long` object. The method obtains the value of the system property as a `String` using `System.getProperty()`.

  If the value of the property begins with `0x` or `#` and is not followed by a minus sign, the rest of the value is parsed as a hexadecimal integer. If the value begins with `0`, it's parsed as an octal integer; otherwise it's parsed as a decimal integer.

#### `public static Long getLong(String nm, long val)`

Parameters

  `nm`

    The name of a system property.

  `val`

    A default value for the property.

Returns

  The value of the system property as a `Long` object or a `Long` object with the value `val` if the named property does not exist or cannot be parsed.

Description

  This method retrieves the value of the named system property and returns it as a `Long` object. The method obtains the value of the system property as a `String` using `System.getProperty()`.

  If the value of the property begins with `0x` or `#` and is not followed by a minus sign, the rest of the value is parsed as a hexadecimal integer. If the value begins with `0`, it's parsed as an octal integer; otherwise it's parsed as a decimal integer.

#### `public static Long getLong(String nm, Long val)`

Parameters

  `nm`

    The name of a system property.

  `val`

    A default value for the property.

Returns

  The value of the system property as a `Long` object, or the `Long` object `val` if the named property does not exist or cannot be parsed.

Description

  This method retrieves the value of the named system property and returns it as a `Long` object. The method obtains the value of the system property as a `String` using `System.getProperty()`.

  If the value of the property begins with `0x` or `#` and is not followed by a minus sign, the rest of the value is parsed as a hexadecimal integer. If the value begins with `0`, it's parsed as an octal integer; otherwise it's parsed as a decimal integer.

### parseLong

####

     public static long parseLong(String s) throws NumberFormatException

Parameters

  `s`

    The `String` to be converted to a `long` value.

Returns

  The numeric value of the `long` represented by the `String` object.

Throws

  `NumberFormatException`

    If the `String` does not contain a valid representation of a `long` value.

Description

  This method returns the numeric value of the `long` 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 long parseLong(String s, int radix) throws NumberFormatException

Parameters

  `s`

    The `String` to be converted to a `long` value.

  `radix`

    The radix used in interpreting the characters in the `String` as digits. It 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 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 `long` represented by the `String` object in the specified radix.

Throws

  `NumberFormatException`

    If the `String` does not contain a valid representation of a `long` or `radix` is not in the appropriate range.

Description

  This method returns the numeric value of the `long` 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.

### toBinaryString

#### `public static String toBinaryString(long value)`

Parameters

  `value`

    The `long` value to be converted to a string.

Returns

  A string that contains the binary representation of the given value.

Description

  This method returns a `String` object that contains the representation of the given value as an unsigned binary number. To convert the given value to an unsigned quantity, the method simply uses the value as if it were not negative. In other words, if the given value is negative, the method adds 2^64 to it. Otherwise the value is used as it is.

  The string returned by this method contains a sequence of one or more `0' and `1' characters. The method returns "0" if its argument is `0`. Otherwise, the string returned by this method begins with `1'.

### toHexString

#### `public static String toHexString(long value)`

Parameters

  `value`

    The `long` value to be converted to a string.

Returns

  A string that contains the hexadecimal representation of the given value.

Description

  This method returns a `String` object that contains the representation of the given value as an unsigned hexadecimal number. To convert the given value to an unsigned quantity, the method simply uses the value as if it were not negative. In other words, if the given value is negative, the method adds 2^64 to it. Otherwise the value is used as it is.

  The string returned by this method contains a sequence of one or more of the characters `0', `1', `2', `3', `4', `5', `6', `7', `8', `9', `a', `b', `c', `d', `e', and `f'. The method returns "0" if its argument is `0`. Otherwise, the string returned by this method does not begin with `0'.

  To produce a string that contains upper- instead of lowercase letters, use the `String.toUpperCase()` method.

### toOctalString

#### `public static String toOctalString(long value)`

Parameters

  `value`

    The `long` value to be converted to a string.

Returns

  A string that contains the octal representation of the given value.

Description

  This method returns a `String` object that contains a representation of the given value as an unsigned octal number. To convert the given value to an unsigned quantity, the method simply uses the value as if it were not negative. In other words, if the given value is negative, the method adds 2^64 to it. Otherwise the value is used as it is.

  The string returned by this method contains a sequence of one or more of the characters `0', `1', `2', `3', `4', `5', `6', and `7'. The method returns "0" if its argument is `0`. Otherwise, the string returned by this method does not begin with `0'.

### toString

#### `public static String toString(long i)`

Parameters

  `i`

    The `long` 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".

#### `public static String toString(long i, int radix)`

Parameters

  `i`

    The `long` value to be converted to a string.

  `radix`

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

Returns

  The string representation of the given value in the specified radix.

Description

  This method returns a `String` object that contains the representation of the given value in the specified radix.

  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 characters that represent the magnitude of the given value. The characters that can appear in the sequence are determined by the value of `radix`. If N is the value of `radix`, the first N characters on the following line can appear in the sequence:

      0123456789abcdefghijklmnopqrstuvwxyz

  The method does not verify that `radix` is in the proper range. If `radix` is less than `Character.MIN_RADIX` or greater than `Character.MAX_RADIX`, the value 10 is used instead of the given value.

  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 Long valueOf(String s) throws NumberFormatException

Parameters

  `s`

    The string to be made into a `Long` object.

Returns

  The `Long` object constructed from the string.

Throws

  `NumberFormatException`

    If the `String` does not contain a valid representation of a `long`.

Description

  Constructs a `Long` 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 Long valueOf(String s, int radix) throws NumberFormatException

Parameters

  `s`

    The string to be made into a `Long` 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 `Long` object constructed from the string.

Throws

  `NumberFormatException`

    If the `String` does not contain a valid representation of a `long`.

Description

  Constructs a `Long` 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`.

  The method does not verify that `radix` is in the proper range. If `radix` is less than `Character.MIN_RADIX` or greater than `Character.MAX_RADIX`, the value 10 is used instead of the given value.

## Instance Methods

### byteValue

#### `public byte byteValue()`

Availability

  New as of JDK 1.1

Returns

  The value of this object as a `byte`.

Overrides

  `Number.byteValue()`

Description

  This method returns the value of this object as a `byte`. The high order bits of the value are discarded.

### 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`. Rounding may occur.

### 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 `Long` 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`. Rounding may occur.

### hashCode

#### `public int hashCode()`

Returns

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

Overrides

  `Object.hashCode()`

Description

  This method returns a hashcode computed from the value of this object. More specifically, the result is the exclusive OR of the two halves of the `long` value represented by the object. If `value` is the value of the object, the method returns a result equivalent to the following expression:

      (int)(value^(value>>>32))

### 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`. The high-order bits of the value are discarded.

### 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()`

Availability

  New as of JDK 1.1

Returns

  The value of this object as a `short`.

Overrides

  `Number.shortValue()`

Description

  This method returns the value of this object as a `short`. The high-order bits of the value are discarded.

### 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 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 the value of the object 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`, `Integer`, `Number`, `NumberFormatException`, `String`, `System`

LinkageError |  | Math