public final class OptionalLong extends Object
long
value. If a value is present, isPresent()
returns true
. If no value is present, the object is considered empty and isPresent()
returns false
. Additional methods that depend on the presence or absence of a contained value are provided, such as orElse()
(returns a default value if no value is present) and ifPresent()
(performs an action if a value is present).
This is a value-based class; programmers should treat instances that are equal as interchangeable and should not use instances for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail.
OptionalLong
is primarily intended for use as a method return type where there is a clear need to represent "no result." A variable whose type is OptionalLong
should never itself be null
; it should always point to an OptionalLong
instance.Modifier and Type | Method | Description |
---|---|---|
static OptionalLong |
empty() |
Returns an empty OptionalLong instance. |
boolean |
equals |
Indicates whether some other object is "equal to" this OptionalLong . |
long |
getAsLong() |
If a value is present, returns the value, otherwise throws NoSuchElementException . |
int |
hashCode() |
Returns the hash code of the value, if present, otherwise 0 (zero) if no value is present. |
void |
ifPresent |
If a value is present, performs the given action with the value, otherwise does nothing. |
void |
ifPresentOrElse |
If a value is present, performs the given action with the value, otherwise performs the given empty-based action. |
boolean |
isEmpty() |
If a value is not present, returns true , otherwise false . |
boolean |
isPresent() |
If a value is present, returns true , otherwise false . |
static OptionalLong |
of |
Returns an OptionalLong describing the given value. |
long |
orElse |
If a value is present, returns the value, otherwise returns other . |
long |
orElseGet |
If a value is present, returns the value, otherwise returns the result produced by the supplying function. |
long |
orElseThrow() |
If a value is present, returns the value, otherwise throws NoSuchElementException . |
<X extends Throwable> |
orElseThrow |
If a value is present, returns the value, otherwise throws an exception produced by the exception supplying function. |
LongStream |
stream() |
If a value is present, returns a sequential LongStream containing only that value, otherwise returns an empty LongStream . |
String |
toString() |
Returns a non-empty string representation of this OptionalLong suitable for debugging. |
public static OptionalLong empty()
OptionalLong
instance. No value is present for this OptionalLong
.==
or !=
against instances returned by OptionalLong.empty()
. There is no guarantee that it is a singleton. Instead, use isEmpty()
or isPresent()
.OptionalLong
.public static OptionalLong of(long value)
OptionalLong
describing the given value.value
- the value to describeOptionalLong
with the value presentpublic long getAsLong()
NoSuchElementException
.orElseThrow()
.OptionalLong
NoSuchElementException
- if no value is presentpublic boolean isPresent()
true
, otherwise false
.true
if a value is present, otherwise false
public boolean isEmpty()
true
, otherwise false
.true
if a value is not present, otherwise false
public void ifPresent(LongConsumer action)
action
- the action to be performed, if a value is presentNullPointerException
- if value is present and the given action is null
public void ifPresentOrElse(LongConsumer action, Runnable emptyAction)
action
- the action to be performed, if a value is presentemptyAction
- the empty-based action to be performed, if no value is presentNullPointerException
- if a value is present and the given action is null
, or no value is present and the given empty-based action is null
.public LongStream stream()
LongStream
containing only that value, otherwise returns an empty LongStream
.Stream
of optional longs to an LongStream
of present longs:
Stream<OptionalLong> os = ..
LongStream s = os.flatMapToLong(OptionalLong::stream)
LongStream
public long orElse(long other)
other
.other
- the value to be returned, if no value is presentother
public long orElseGet(LongSupplier supplier)
supplier
- the supplying function that produces a value to be returnedNullPointerException
- if no value is present and the supplying function is null
public long orElseThrow()
NoSuchElementException
.OptionalLong
NoSuchElementException
- if no value is presentpublic <X extends Throwable> long orElseThrow(Supplier<? extends X> exceptionSupplier) throws X
IllegalStateException::new
X
- Type of the exception to be thrownexceptionSupplier
- the supplying function that produces an exception to be thrownX
- if no value is presentNullPointerException
- if no value is present and the exception supplying function is null
public boolean equals(Object obj)
OptionalLong
. The other object is considered equal if: OptionalLong
and; ==
. public int hashCode()
0
(zero) if no value is present.public String toString()
OptionalLong
suitable for debugging. The exact presentation format is unspecified and may vary between implementations and versions.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/OptionalLong.html