Added in API level 24

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

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:
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