Added in API level 24

OptionalLong

public final class OptionalLong
extends Object

java.lang.Object
   ↳ java.util.OptionalLong


A container object which may or may not contain a 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.

Summary

Public methods

static OptionalLong empty()

Returns an empty OptionalLong instance.

boolean equals(Object obj)

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(LongConsumer action)

If a value is present, performs the given action with the value, otherwise does nothing.

void ifPresentOrElse(LongConsumer action, Runnable emptyAction)

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(long value)

Returns an OptionalLong describing the given value.

long orElse(long other)

If a value is present, returns the value, otherwise returns other.

long orElseGet(LongSupplier supplier)

If a value is present, returns the value, otherwise returns the result produced by the supplying function.

<X extends Throwable> long orElseThrow(Supplier<? extends X> exceptionSupplier)

If a value is present, returns the value, otherwise throws an exception produced by the exception supplying function.

long orElseThrow()

If a value is present, returns the value, otherwise throws NoSuchElementException.

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.

Inherited methods

Public methods

empty

Added in API level 24
public static OptionalLong empty ()

Returns an empty OptionalLong instance. No value is present for this OptionalLong.

API Note:
  • Though it may be tempting to do so, avoid testing if an object is empty by comparing with == or != against instances returned by OptionalLong.empty(). There is no guarantee that it is a singleton. Instead, use isEmpty() or isPresent().
Returns
OptionalLong an empty OptionalLong.

equals

Added in API level 24
public boolean equals (Object obj)

Indicates whether some other object is "equal to" this OptionalLong. The other object is considered equal if:

  • it is also an OptionalLong and;
  • both instances have no value present or;
  • the present values are "equal to" each other via ==.

Parameters
obj Object: an object to be tested for equality

Returns
boolean true if the other object is "equal to" this object otherwise false

getAsLong

Added in API level 24
public long getAsLong ()

If a value is present, returns the value, otherwise throws NoSuchElementException.

API Note:
Returns
long the value described by this OptionalLong

Throws
NoSuchElementException if no value is present

hashCode

Added in API level 24
public int hashCode ()

Returns the hash code of the value, if present, otherwise 0 (zero) if no value is present.

Returns
int hash code value of the present value or 0 if no value is present

ifPresent

Added in API level 24
public void ifPresent (LongConsumer action)

If a value is present, performs the given action with the value, otherwise does nothing.

Parameters
action LongConsumer: the action to be performed, if a value is present

Throws
NullPointerException if value is present and the given action is null

ifPresentOrElse

Added in API level 33
public void ifPresentOrElse (LongConsumer action, 
                Runnable emptyAction)

If a value is present, performs the given action with the value, otherwise performs the given empty-based action.

Parameters
action LongConsumer: the action to be performed, if a value is present

emptyAction Runnable: the empty-based action to be performed, if no value is present

Throws
NullPointerException if a value is present and the given action is null, or no value is present and the given empty-based action is null.

isEmpty

Added in API level 33
public boolean isEmpty ()

If a value is not present, returns true, otherwise false.

Returns
boolean true if a value is not present, otherwise false

isPresent

Added in API level 24
public boolean isPresent ()

If a value is present, returns true, otherwise false.

Returns
boolean true if a value is present, otherwise false

of

Added in API level 24
public static OptionalLong of (long value)

Returns an OptionalLong describing the given value.

Parameters
value long: the value to describe

Returns
OptionalLong an OptionalLong with the value present

orElse

Added in API level 24
public long orElse (long other)

If a value is present, returns the value, otherwise returns other.

Parameters
other long: the value to be returned, if no value is present

Returns
long the value, if present, otherwise other

orElseGet

Added in API level 24
public long orElseGet (LongSupplier supplier)

If a value is present, returns the value, otherwise returns the result produced by the supplying function.

Parameters
supplier LongSupplier: the supplying function that produces a value to be returned

Returns
long the value, if present, otherwise the result produced by the supplying function

Throws
NullPointerException if no value is present and the supplying function is null

orElseThrow

Added in API level 24
public long orElseThrow (Supplier<? extends X> exceptionSupplier)

If a value is present, returns the value, otherwise throws an exception produced by the exception supplying function.

API Note:
  • A method reference to the exception constructor with an empty argument list can be used as the supplier. For example, IllegalStateException::new
Parameters
exceptionSupplier Supplier: the supplying function that produces an exception to be thrown

Returns
long the value, if present

Throws
if no value is present
NullPointerException if no value is present and the exception supplying function is null
Throwable

orElseThrow

Added in API level 33
public long orElseThrow ()

If a value is present, returns the value, otherwise throws NoSuchElementException.

Returns
long the value described by this OptionalLong

Throws
NoSuchElementException if no value is present

stream

Added in API level 33
public LongStream stream ()

If a value is present, returns a sequential LongStream containing only that value, otherwise returns an empty LongStream.

API Note:
  • This method can be used to transform a Stream of optional longs to an LongStream of present longs:
    Stream<OptionalLong> os = ..
         LongStream s = os.flatMapToLong(OptionalLong::stream)
     
Returns
LongStream the optional value as an LongStream

toString

Added in API level 24
public String toString ()

Returns a non-empty string representation of this OptionalLong suitable for debugging. The exact presentation format is unspecified and may vary between implementations and versions.

Implementation Requirements:
  • If a value is present the result must include its string representation in the result. Empty and present OptionalLongs must be unambiguously differentiable.
Returns
String the string representation of this instance