OptionalDouble

AI-generated Key Takeaways

• OptionalDouble is a container that may or may not hold a double value.

• It provides methods to check for the presence of a value (isPresent), retrieve the value if present (getAsDouble), and specify default behaviors or actions if a value is missing (orElse, orElseGet, ifPresent).

• If a value is not present and you try to access it directly using getAsDouble, a NoSuchElementException will be thrown.

• You can create an empty OptionalDouble using empty() or an OptionalDouble with a value using of(double).

public final class OptionalDouble extends Object

A container object which may or may not contain a double value. If a value is present, isPresent() will return true and getAsDouble() will return the value.

Additional methods that depend on the presence or absence of a contained value are provided, such as orElse() (return a default value if value not present) and ifPresent() (execute a block of code if the value is present).

Public Method Summary

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 in this OptionalDouble, returns the value, otherwise throws NoSuchElementException.
int	hashCode() Returns the hash code value of the present value, if any, or 0 (zero) if no value is present.
void	ifPresent(DoubleConsumer consumer) Have the specified consumer accept the value if a value is present, otherwise do nothing.
boolean	isPresent() Return true if there is a value present, otherwise false.
static OptionalDouble	of(double value) Return an OptionalDouble with the specified value present.
double	orElse(double other) Return the value if present, otherwise return other.
double	orElseGet(DoubleSupplier other) Return the value if present, otherwise invoke other and return the result of that invocation.
<X extends Throwable> double	orElseThrow(Supplier<X> exceptionSupplier) Return the contained value, if present, otherwise throw an exception to be created by the provided supplier.
String	toString() Returns a string containing a concise, human-readable description of this object. Returns a non-empty string representation of this object suitable for debugging.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Public Methods

public static OptionalDouble empty ()

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

Returns

• an empty OptionalDouble.

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	an object to be tested for equality

Returns

• {code true} if the other object is "equal to" this object otherwise false

public double getAsDouble ()

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

Returns

• the value held by this OptionalDouble

Throws

NoSuchElementException	if there is no value present

See Also

• isPresent()

public int hashCode ()

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

Returns

• hash code value of the present value or 0 if no value is present

public void ifPresent (DoubleConsumer consumer)

Have the specified consumer accept the value if a value is present, otherwise do nothing.

Parameters

consumer	block to be executed if a value is present

Throws

NullPointerException	if value is present and consumer is null

public boolean isPresent ()

Return true if there is a value present, otherwise false.

Returns

• true if there is a value present, otherwise false

public static OptionalDouble of (double value)

Return an OptionalDouble with the specified value present.

Parameters

value	the value to be present

Returns

• an OptionalDouble with the value present

public double orElse (double other)

Return the value if present, otherwise return other.

Parameters

other	the value to be returned if there is no value present

Returns

• the value, if present, otherwise other

public double orElseGet (DoubleSupplier other)

Return the value if present, otherwise invoke other and return the result of that invocation.

Parameters

other	a DoubleSupplier whose result is returned if no value is present

Returns

• the value if present otherwise the result of other.getAsDouble()

Throws

NullPointerException	if value is not present and other is null

public double orElseThrow (Supplier<X> exceptionSupplier)

Return the contained value, if present, otherwise throw an exception to be created by the provided supplier.

Parameters

exceptionSupplier	The supplier which will return the exception to be thrown

Returns

• the present value

Throws

	if there is no value present
NullPointerException	if no value is present and exceptionSupplier is null
Throwable

public String toString ()

Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression:

   getClass().getName() + '@' + Integer.toHexString(hashCode())

See Writing a useful toString method if you intend implementing your own toString method. Returns a non-empty string representation of this object suitable for debugging. The exact presentation format is unspecified and may vary between implementations and versions.

Returns

• the string representation of this instance