OptionalDouble

public final class OptionalDouble
extends Object

java.lang.Object
↳	java.util.OptionalDouble

A container object which may or may not contain a double 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 OptionalDouble`	`empty()` Returns an empty `OptionalDouble` instance.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this `OptionalDouble`.
`double`	`getAsDouble()` 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(DoubleConsumer action)` If a value is present, performs the given action with the value, otherwise does nothing.
`void`	`ifPresentOrElse(DoubleConsumer 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 OptionalDouble`	`of(double value)` Returns an `OptionalDouble` describing the given value.
`double`	`orElse(double other)` If a value is present, returns the value, otherwise returns `other`.
`double`	`orElseGet(DoubleSupplier supplier)` If a value is present, returns the value, otherwise returns the result produced by the supplying function.
`<X extends Throwable> double`	`orElseThrow(Supplier<? extends X> exceptionSupplier)` If a value is present, returns the value, otherwise throws an exception produced by the exception supplying function.
`double`	`orElseThrow()` If a value is present, returns the value, otherwise throws `NoSuchElementException`.
`DoubleStream`	`stream()` If a value is present, returns a sequential `DoubleStream` containing only that value, otherwise returns an empty `DoubleStream`.
`String`	`toString()` Returns a non-empty string representation of this `OptionalDouble` 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 OptionalDouble empty ()

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

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 OptionalDouble.empty(). There is no guarantee that it is a singleton. Instead, use isEmpty() or isPresent().

Returns
`OptionalDouble`	an empty `OptionalDouble`.

equals

Added in API level 24

 public boolean equals (Object obj)

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

it is also an OptionalDouble and;
both instances have no value present or;
the present values are "equal to" each other via Double.compare() == 0.

Parameters
`obj`	`Object`: an object to be tested for equality

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

getAsDouble

Added in API level 24

 public double getAsDouble ()

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

API Note:

The preferred alternative to this method is orElseThrow().

Returns
`double`	the value described by this `OptionalDouble`

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 (DoubleConsumer action)

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

Parameters
`action`	`DoubleConsumer`: 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 (DoubleConsumer action, Runnable emptyAction)

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

Parameters
`action`	`DoubleConsumer`: 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 OptionalDouble of (double value)

Returns an OptionalDouble describing the given value.

Parameters
`value`	`double`: the value to describe

Returns
`OptionalDouble`	an `OptionalDouble` with the value present

orElse

Added in API level 24

 public double orElse (double other)

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

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

Returns
`double`	the value, if present, otherwise `other`

orElseGet

Added in API level 24

 public double orElseGet (DoubleSupplier supplier)

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

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

Returns
`double`	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 double 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
`double`	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 double orElseThrow ()

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

Returns
`double`	the value described by this `OptionalDouble`

Throws
`NoSuchElementException`	if no value is present

stream

Added in API level 33

 public DoubleStream stream ()

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

API Note:

This method can be used to transform a Stream of optional doubles to a DoubleStream of present doubles:
```
Stream<OptionalDouble> os = .. DoubleStream s = os.flatMapToDouble(OptionalDouble::stream) 
```

Returns
`DoubleStream`	the optional value as a `DoubleStream`

toString

Added in API level 24

 public String toString ()

Returns a non-empty string representation of this OptionalDouble 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 OptionalDoubles must be unambiguously differentiable.

Returns
`String`	the string representation of this instance