@CheckReturnValue @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.
| 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. |
| 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 Converter<String,Long> |
stringConverter()
Returns a serializable converter object that converts between strings and longs using
Long.decode(java.lang.String) and Long.toString(). |
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.
|
static Long |
tryParse(String string,
int radix)
Parses the specified string as a signed long value using the specified radix.
|
public static final int BYTES
The number of bytes required to represent a primitive long value.
public static final long MAX_POWER_OF_TWO
The largest power of two that can be represented as a long.
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.
value - a primitive long valuepublic 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).
Note for Java 7 and later: this method should be treated as deprecated; use the equivalent Long.compare(long, long) method instead.
a - the first long to compareb - the second long to comparea is less than b; a positive value if a is greater than b; or zero if they are equalpublic static boolean contains(long[] array,
long target)
Returns true if target is present as an element anywhere in array.
array - an array of long values, possibly emptytarget - a primitive long valuetrue if array[i] == target for some value of ipublic static int indexOf(long[] array,
long target)
Returns the index of the first appearance of the value target in array.
array - an array of long values, possibly emptytarget - a primitive long valuei for which array[i] == target, or -1 if no such index exists.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.
array - the array to search for the sequence targettarget - the array to search for as a sub-sequence of arraypublic static int lastIndexOf(long[] array,
long target)
Returns the index of the last appearance of the value target in array.
array - an array of long values, possibly emptytarget - a primitive long valuei for which array[i] == target, or -1 if no such index exists.public static long min(long... array)
Returns the least value present in array.
array - a nonempty array of long valuesarray that is less than or equal to every other value in the arrayIllegalArgumentException - if array is emptypublic static long max(long... array)
Returns the greatest value present in array.
array - a nonempty array of long valuesarray that is greater than or equal to every other value in the arrayIllegalArgumentException - if array is emptypublic 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}.
arrays - zero or more long arrayspublic 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 to get a growable buffer.
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.
IllegalArgumentException - if bytes has fewer than 8 elementspublic 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}).
@Beta @Nullable @CheckForNull 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. Additionally, this method only accepts ASCII digits, and returns null if non-ASCII digits are present in the string.
Note that strings prefixed with ASCII '+' are rejected, even under JDK 7, despite the change to Long.parseLong(String) for that version.
string - the string representation of a long valuestring, or null if string has a length of zero or cannot be parsed as a long value@Beta @Nullable @CheckForNull public static Long tryParse(String string, int radix)
Parses the specified string as a signed long value using the specified radix. The ASCII character '-' (‘\u002D’) is recognized as the minus sign.
Unlike Long.parseLong(String, int), this method returns null instead of throwing an exception if parsing fails. Additionally, this method only accepts ASCII digits, and returns null if non-ASCII digits are present in the string.
Note that strings prefixed with ASCII '+' are rejected, even under JDK 7, despite the change to Long.parseLong(String, int) for that version.
string - the string representation of an long valueradix - the radix to use when parsingstring using radix, or null if string has a length of zero or cannot be parsed as a long valueIllegalArgumentException - if radix < Character.MIN_RADIX or radix > Character.MAX_RADIX@Beta public static Converter<String,Long> stringConverter()
Returns a serializable converter object that converts between strings and longs using Long.decode(java.lang.String) and Long.toString().
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.
array - the source arrayminLength - the minimum length the returned array must guaranteepadding - an extra amount to “grow” the array by if growth is necessaryarray, with guaranteed minimum length minLengthIllegalArgumentException - if minLength or padding is negativepublic 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".
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 emptypublic 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[]).
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.
collection - a collection of Number instancescollection, in the same order, converted to primitivesNullPointerException - if collection or any of its elements is nullCollection<Long> before 12.0)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.
backingArray - the array to back the list