Added in API level 24

Summary: Methods | Inherited Methods

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

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

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:

The preferred alternative to this method is orElseThrow().

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