Longs (Guava: Google Core Libraries for Java 15.0 API)

java.lang.Object
- com.google.common.primitives.Longs

```
@GwtCompatible
public final class Longs
extends Object
```
Static utility methods pertaining to long primitives, that are not already found in either Long or Arrays.
See the Guava User Guide article on primitive utilities.

Since:

1.0

Author:

Kevin Bourrillion

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`BYTES` The number of bytes required to represent a primitive `long` value.
`static long`	`MAX_POWER_OF_TWO` The largest power of two that can be represented as a `long`.

Method Summary

Methods
Modifier and Type	Method and Description
`static List<Long>`	`asList(long... backingArray)` Returns a fixed-size list backed by the specified array, similar to `Arrays.asList(Object[])`.
`static int`	`compare(long a, long b)` Compares the two specified `long` values.
`static long[]`	`concat(long[]... arrays)` Returns the values from each provided array combined into a single array.
`static boolean`	`contains(long[] array, long target)` Returns `true` if `target` is present as an element anywhere in `array`.
`static long[]`	`ensureCapacity(long[] array, int minLength, int padding)` Returns an array containing the same values as `array`, but guaranteed to be of a specified minimum length.
`static long`	`fromByteArray(byte[] bytes)` Returns the `long` value whose big-endian representation is stored in the first 8 bytes of `bytes`; equivalent to `ByteBuffer.wrap(bytes).getLong()`.
`static long`	`fromBytes(byte b1, byte b2, byte b3, byte b4, byte b5, byte b6, byte b7, byte b8)` Returns the `long` value whose byte representation is the given 8 bytes, in big-endian order; equivalent to `Longs.fromByteArray(new byte[] {b1, b2, b3, b4, b5, b6, b7, b8})`.
`static int`	`hashCode(long value)` Returns a hash code for `value`; equal to the result of invoking `((Long) value).hashCode()`.
`static int`	`indexOf(long[] array, long target)` Returns the index of the first appearance of the value `target` in `array`.
`static int`	`indexOf(long[] array, long[] target)` Returns the start position of the first occurrence of the specified `target` within `array`, or `-1` if there is no such occurrence.
`static String`	`join(String separator, long... array)` Returns a string containing the supplied `long` values separated by `separator`.
`static int`	`lastIndexOf(long[] array, long target)` Returns the index of the last appearance of the value `target` in `array`.
`static Comparator<long[]>`	`lexicographicalComparator()` Returns a comparator that compares two `long` arrays lexicographically.
`static long`	`max(long... array)` Returns the greatest value present in `array`.
`static long`	`min(long... array)` Returns the least value present in `array`.
`static long[]`	`toArray(Collection<? extends Number> collection)` Returns an array containing each value of `collection`, converted to a `long` value in the manner of `Number.longValue()`.
`static byte[]`	`toByteArray(long value)` Returns a big-endian representation of `value` in an 8-element byte array; equivalent to `ByteBuffer.allocate(8).putLong(value).array()`.
`static Long`	`tryParse(String string)` Parses the specified string as a signed decimal long value.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - BYTES
```
public static final int BYTES
```
    The number of bytes required to represent a primitive long value.
    
    See Also:
    Constant Field Values
  - MAX_POWER_OF_TWO
```
public static final long MAX_POWER_OF_TWO
```
    The largest power of two that can be represented as a long.
    
    Since:
    
    10.0
    
    See Also:
    Constant Field Values
- Method Detail
  - hashCode
```
public static int hashCode(long value)
```
    Returns a hash code for value; equal to the result of invoking ((Long) value).hashCode().
    This method always return the value specified by Long.hashCode() in java, which might be different from ((Long) value).hashCode() in GWT because Long.hashCode() in GWT does not obey the JRE contract.
    
    Parameters:
    value - a primitive long value
    
    Returns:
    a hash code for the value
  - compare
```
public static int compare(long a,
          long b)
```
    Compares the two specified long values. The sign of the value returned is the same as that of ((Long) a).compareTo(b).
    
    Parameters:
    a - the first long to compare
    b - the second long to compare
    
    Returns:
    a negative value if a is less than b; a positive value if a is greater than b; or zero if they are equal
  - contains
```
public static boolean contains(long[] array,
               long target)
```
    Returns true if target is present as an element anywhere in array.
    
    Parameters:
    array - an array of long values, possibly empty
    target - a primitive long value
    
    Returns:
    true if array[i] == target for some value of i
  - indexOf
```
public static int indexOf(long[] array,
          long target)
```
    Returns the index of the first appearance of the value target in array.
    
    Parameters:
    array - an array of long values, possibly empty
    target - a primitive long value
    
    Returns:
    the least index i for which array[i] == target, or -1 if no such index exists.
  - indexOf
```
public static int indexOf(long[] array,
          long[] target)
```
    Returns the start position of the first occurrence of the specified target within array, or -1 if there is no such occurrence.
    More formally, returns the lowest index i such that java.util.Arrays.copyOfRange(array, i, i + target.length) contains exactly the same elements as target.
    
    Parameters:
    array - the array to search for the sequence target
    target - the array to search for as a sub-sequence of array
  - lastIndexOf
```
public static int lastIndexOf(long[] array,
              long target)
```
    Returns the index of the last appearance of the value target in array.
    
    Parameters:
    array - an array of long values, possibly empty
    target - a primitive long value
    
    Returns:
    the greatest index i for which array[i] == target, or -1 if no such index exists.
  - min
```
public static long min(long... array)
```
    Returns the least value present in array.
    
    Parameters:
    array - a nonempty array of long values
    
    Returns:
    the value present in array that is less than or equal to every other value in the array
    
    Throws:
    
    IllegalArgumentException - if array is empty
  - max
```
public static long max(long... array)
```
    Returns the greatest value present in array.
    
    Parameters:
    array - a nonempty array of long values
    
    Returns:
    the value present in array that is greater than or equal to every other value in the array
    
    Throws:
    
    IllegalArgumentException - if array is empty
  - concat
```
public static long[] concat(long[]... arrays)
```
    Returns the values from each provided array combined into a single array. For example, concat(new long[] {a, b}, new long[] {}, new long[] {c} returns the array {a, b, c}.
    
    Parameters:
    arrays - zero or more long arrays
    
    Returns:
    a single array containing all the values from the source arrays, in order
  - toByteArray
```
public static byte[] toByteArray(long value)
```
    Returns a big-endian representation of value in an 8-element byte array; equivalent to ByteBuffer.allocate(8).putLong(value).array(). For example, the input value 0x1213141516171819L would yield the byte array {0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19}.
    If you need to convert and concatenate several values (possibly even of different types), use a shared ByteBuffer instance, or use ByteStreams.newDataOutput() to get a growable buffer.
  - fromByteArray
```
public static long fromByteArray(byte[] bytes)
```
    Returns the long value whose big-endian representation is stored in the first 8 bytes of bytes; equivalent to ByteBuffer.wrap(bytes).getLong(). For example, the input byte array {0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19} would yield the long value 0x1213141516171819L.
    Arguably, it's preferable to use ByteBuffer; that library exposes much more flexibility at little cost in readability.
    
    Throws:
    
    IllegalArgumentException - if bytes has fewer than 8 elements
  - fromBytes
```
public static long fromBytes(byte b1,
             byte b2,
             byte b3,
             byte b4,
             byte b5,
             byte b6,
             byte b7,
             byte b8)
```
    Returns the long value whose byte representation is the given 8 bytes, in big-endian order; equivalent to Longs.fromByteArray(new byte[] {b1, b2, b3, b4, b5, b6, b7, b8}).
    
    Since:
    
    7.0
  - tryParse
```
@Beta
public static Long tryParse(String string)
```
    Parses the specified string as a signed decimal long value. The ASCII character '-' ('\u002D') is recognized as the minus sign.
    Unlike Long.parseLong(String), this method returns null instead of throwing an exception if parsing fails.
    Note that strings prefixed with ASCII '+' are rejected, even under JDK 7, despite the change to Long.parseLong(String) for that version.
    
    Parameters:
    string - the string representation of a long value
    
    Returns:
    the long value represented by string, or null if string has a length of zero or cannot be parsed as a long value
    Since:
    
    14.0
  - ensureCapacity
```
public static long[] ensureCapacity(long[] array,
                    int minLength,
                    int padding)
```
    Returns an array containing the same values as array, but guaranteed to be of a specified minimum length. If array already has a length of at least minLength, it is returned directly. Otherwise, a new array of size minLength + padding is returned, containing the values of array, and zeroes in the remaining places.
    
    Parameters:
    array - the source array
    minLength - the minimum length the returned array must guarantee
    padding - an extra amount to "grow" the array by if growth is necessary
    
    Returns:
    an array containing the values of array, with guaranteed minimum length minLength
    
    Throws:
    
    IllegalArgumentException - if minLength or padding is negative
  - join
```
public static String join(String separator,
          long... array)
```
    Returns a string containing the supplied long values separated by separator. For example, join("-", 1L, 2L, 3L) returns the string "1-2-3".
    
    Parameters:
    separator - the text that should appear between consecutive values in the resulting string (but not at the start or end)
    array - an array of long values, possibly empty
  - lexicographicalComparator
```
public static Comparator<long[]> lexicographicalComparator()
```
    Returns a comparator that compares two long arrays lexicographically. That is, it compares, using compare(long, long)), the first pair of values that follow any common prefix, or when one array is a prefix of the other, treats the shorter array as the lesser. For example, [] < [1L] < [1L, 2L] < [2L].
    The returned comparator is inconsistent with Object.equals(Object) (since arrays support only identity equality), but it is consistent with Arrays.equals(long[], long[]).
    
    Since:
    
    2.0
    
    See Also:
    Lexicographical order article at Wikipedia
  - toArray
```
public static long[] toArray(Collection<? extends Number> collection)
```
    Returns an array containing each value of collection, converted to a long value in the manner of Number.longValue().
    Elements are copied from the argument collection as if by collection.toArray(). Calling this method is as thread-safe as calling that method.
    
    Parameters:
    collection - a collection of Number instances
    
    Returns:
    an array containing the same values as collection, in the same order, converted to primitives
    
    Throws:
    
    NullPointerException - if collection or any of its elements is null
    Since:
    
    1.0 (parameter was Collection<Long> before 12.0)
  - asList
```
public static List<Long> asList(long... backingArray)
```
    Returns a fixed-size list backed by the specified array, similar to Arrays.asList(Object[]). The list supports List.set(int, Object), but any attempt to set a value to null will result in a NullPointerException.
    The returned list maintains the values, but not the identities, of Long objects written to or read from it. For example, whether list.get(0) == list.get(0) is true for the returned list is unspecified.
    
    Parameters:
    backingArray - the array to back the list
    
    Returns:
    a list view of the array

Class Longs

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

BYTES

MAX_POWER_OF_TWO

Method Detail

hashCode

compare

contains

indexOf

indexOf

lastIndexOf

min

max

concat

toByteArray

fromByteArray

fromBytes

tryParse

ensureCapacity

join

lexicographicalComparator

toArray

asList