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 |
boolean
|
equals(Object obj)
Indicates whether some other object is "equal to" this
|
double
|
getAsDouble()
If a value is present, returns the value, otherwise throws
|
int
|
hashCode()
Returns the hash code of the value, if present, otherwise |
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 |
boolean
|
isPresent()
If a value is present, returns |
static
OptionalDouble
|
of(double value)
Returns an |
double
|
orElse(double other)
If a value is present, returns the value, otherwise returns
|
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
|
DoubleStream
|
stream()
If a value is present, returns a sequential |
String
|
toString()
Returns a non-empty string representation of this |
Inherited methods | |
---|---|
Public methods
empty
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 byOptionalDouble.empty()
. There is no guarantee that it is a singleton. Instead, useisEmpty()
orisPresent()
.
Returns | |
---|---|
OptionalDouble |
an empty OptionalDouble . |
equals
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
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
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
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
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
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
public boolean isPresent ()
If a value is present, returns true
, otherwise false
.
Returns | |
---|---|
boolean |
true if a value is present, otherwise false |
of
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
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
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
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
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
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 aDoubleStream
of present doubles:Stream<OptionalDouble> os = .. DoubleStream s = os.flatMapToDouble(OptionalDouble::stream)
Returns | |
---|---|
DoubleStream |
the optional value as a DoubleStream |
toString
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
OptionalDouble
s must be unambiguously differentiable.
Returns | |
---|---|
String |
the string representation of this instance |