de.fhg.fokus.xtensions.optional

Class OptionalDoubleExtensions

java.lang.Object

de.fhg.fokus.xtensions.optional.OptionalDoubleExtensions

public final class OptionalDoubleExtensions
extends Object

This class contains static functions that ease the work with Java 8 OptionalDouble.
To make easy use of this functions import this extensions like this in your Xtend source:

  import static extension de.fhg.fokus.xtenders.optional.OptionalDoubleExtensions.*
 

Author:

Max Bureck

See Also:

OptionalExtensions, OptionalIntExtensions, OptionalLongExtensions

Method Summary

Modifier and Type	Method and Description
static @NonNull DoubleIterable	asIterable(@NonNull OptionalDouble self) Returns a DoubleIterable that either provides the one value present in self, or an DoubleIterable providing no value if self is empty.
static @NonNull Optional<Double>	boxed(@NonNull OptionalDouble self) Returns an Optional<Double> holding the value of self, or returns an empty optional, if the given OptionalDouble is empty.
static @NonNull OptionalDouble	filter(@NonNull OptionalDouble self, @NonNull DoublePredicate predicate) If the given OptionalDouble self holds a value and the value tests positive with the given DoublePredicate predicate, returns self, otherwise returns an empty OptionalDouble.
static @NonNull OptionalDouble	flatMapDouble(@NonNull OptionalDouble self, @NonNull DoubleFunction<OptionalDouble> mapFunc) Maps the value of self to an OptionalDouble using mapFunc, if self has a present value.
static void	ifNotPresent(@NonNull OptionalDouble self, @NonNull Procedures.Procedure0 then) Calls the procedure then if the optional self holds no value.
static void	ifPresentOrElse(OptionalDouble self, DoubleConsumer action, Runnable emptyAction) Will call action with the value held by self if it is not empty.
static @NonNull PrimitiveIterator.OfDouble	iterator(@NonNull OptionalDouble self) Returns an PrimitiveIterable.OfDouble that either provides the one value present in self, or an PrimitiveIterable.OfDouble providing no value if self is empty.
static <V> @NonNull Optional<V>	map(@NonNull OptionalDouble self, @NonNull DoubleFunction<V> mapFunc) Maps the value held by self to an object wrapped in Optional if present, returns an empty Optional otherwise.
static @NonNull OptionalDouble	mapDouble(@NonNull OptionalDouble self, @NonNull DoubleUnaryOperator mapFunc) Maps the value of self to a double value wrapped into an OptionalDouble, if self holds a value.
static @NonNull OptionalInt	mapInt(@NonNull OptionalDouble self, @NonNull DoubleToIntFunction mapFunc) Maps the value of self to an int value wrapped into an OptionalInt, if self holds a value.
static @NonNull OptionalLong	mapLong(@NonNull OptionalDouble self, @NonNull DoubleToLongFunction mapFunc) Maps the value of self to a long value wrapped into an OptionalLong, if self holds a value.
static @NonNull OptionalDouble	maybe(@Nullable Double i) This method is a shortcut for the following expression:
static @NonNull OptionalDouble	noDouble() Alias for OptionalDouble.empty().
static double	operator_elvis(@NonNull OptionalDouble o, double alternative) This operator is an alias for:
static double	operator_elvis(@NonNull OptionalDouble o, DoubleSupplier getter) Alias for OptionalDouble.orElseGet(DoubleSupplier).
static @NonNull OptionalDouble	operator_or(@NonNull OptionalDouble self, @NonNull Supplier<? extends OptionalDouble> alternativeSupplier) Operator that will be de-sugared to call to OptionalIntExtensions.or(self,alternative).
static @NonNull OptionalDouble	or(@NonNull OptionalDouble self, @NonNull Supplier<? extends OptionalDouble> alternativeSupplier) This method will either return self if it is not empty, or otherwise the value supplied by alternative.
static @NonNull OptionalDouble	some(double d) This method is an alias for OptionalDouble.of(double).
static @NonNull DoubleStream	stream(@NonNull OptionalDouble self) This extension function returns a stream of a single element if the given optional self contains a value, or no element if the optional is empty.
static @NonNull Set<Double>	toSet(@NonNull OptionalDouble self) Returns an immutable set that either contains the value, held by the optional, or an empty set, if the optional is empty.
static Else	whenPresent(@NonNull OptionalDouble self, @NonNull DoubleConsumer onPresent) This extension method will check if a value is present in self and if so will call onPresent with that value.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

whenPresent

public static Else whenPresent(@NonNull OptionalDouble self,
                               @NonNull DoubleConsumer onPresent)

This extension method will check if a value is present in self and if so will call onPresent with that value. The returned Else will allows to perform a block of code if the optional does not hold a value. Example usage:

 
 val OptionalDouble o = OptionalDouble.of(42.0d)
 o.whenPresent [
 	println(it)
 ].elseDo [
 	println("no val")
 ]
 

Parameters:

self - if holds value, onPresent will be executed with the value held by self.

onPresent - will be executed with value of self, if present.

Returns:

instance of Else that either execute an else block if self has no value present, or ignore the else block if the value is present.

ifNotPresent

public static void ifNotPresent(@NonNull OptionalDouble self,
                                @NonNull Procedures.Procedure0 then)

Calls the procedure then if the optional self holds no value. This method is equivalent to the following code:

  if (!self.isPresent()) {
        then.apply();
 }
 

Parameters:

self - if optional is empty, then will be called.

then - procedure to be called if self does not hold a value.

operator_elvis

@Pure
public static double operator_elvis(@NonNull OptionalDouble o,
                                          double alternative)

This operator is an alias for:

 o.orElse(alternative)
 

Parameters:

o - OptionalDouble checked for a present value

alternative - value to be returned by this extension function, oif o is empty.

Returns:

either the value present in o, or alternative if there is no value present in o.

operator_elvis

@Pure
public static double operator_elvis(@NonNull OptionalDouble o,
                                          DoubleSupplier getter)

Alias for OptionalDouble.orElseGet(DoubleSupplier).

Parameters:

o - optional to be queried for value

getter - will be called to get return value if parameter o is empty.

Returns:

if o has a value present, will return this value. Otherwise returns getter will be called to get return value.

some

@Pure
public static @NonNull OptionalDouble some(double d)

This method is an alias for OptionalDouble.of(double).

Parameters:

d - double to wrap in an OptionalDouble

Returns:

OptionalDouble, having present value d.

noDouble

@Pure
public static @NonNull OptionalDouble noDouble()

Alias for OptionalDouble.empty().

Returns:

an OptionalDouble with no value present.

maybe

@Pure
public static @NonNull OptionalDouble maybe(@Nullable Double i)

This method is a shortcut for the following expression:

  i == null ? OptionalDouble.empty() : OptionalDouble.of(i)
 

Parameters:

i - an Integer that is checked for null. If i == null, then returns an empty OptionalInt. If i != null returns an OptionalInt holding the integer value.

Returns:

an OptionalInt holding i, if i != null, an empty OptionalInt otherwise.

boxed

@Pure
public static @NonNull Optional<Double> boxed(@NonNull OptionalDouble self)

Returns an Optional<Double> holding the value of self, or returns an empty optional, if the given OptionalDouble is empty.

Parameters:

self - value will be extracted from this OptionalDouble, if value is present and wrapped into an Double which will be returned in an Optional from this method.

Returns:

Optional<Double> holding the value of self if present, empty Optional otherwise

filter

public static @NonNull OptionalDouble filter(@NonNull OptionalDouble self,
                                             @NonNull DoublePredicate predicate)

If the given OptionalDouble self holds a value and the value tests positive with the given DoublePredicate predicate, returns self, otherwise returns an empty OptionalDouble.

Parameters:

self - the optional value that will be filtered using predicate

predicate - the test that will be used to filter self.

Returns:

filtered OptionalDouble, empty optional if self is empty or it's content tests negative with predicate. Otherwise returns self.

map

public static <V> @NonNull Optional<V> map(@NonNull OptionalDouble self,
                                           @NonNull DoubleFunction<V> mapFunc)

Maps the value held by self to an object wrapped in Optional if present, returns an empty Optional otherwise.

Type Parameters:

V - type of value the mapFunc mapps to and is then held in the returned optional

Parameters:

self - the optional, that's value should be mapped if present

mapFunc - mapping function mapping the value held by self to an object

Returns:

an empty Optional, if self is empty, otherwise an Optional holding the result of op applied to the value held by self.

mapInt

public static @NonNull OptionalInt mapInt(@NonNull OptionalDouble self,
                                          @NonNull DoubleToIntFunction mapFunc)

Maps the value of self to an int value wrapped into an OptionalInt, if self holds a value. Returns an empty OptionalInt otherwise.

Parameters:

self - optional, that's held value will be mapped with mapFunc, if present

mapFunc - mapping function, to be applied to value of self, if present

Returns:

optional holding the value of self, mapped to int using mapFunc if value present. Empty optional otherwise.

mapLong

public static @NonNull OptionalLong mapLong(@NonNull OptionalDouble self,
                                            @NonNull DoubleToLongFunction mapFunc)

Maps the value of self to a long value wrapped into an OptionalLong, if self holds a value. Returns an empty OptionalInt otherwise.

Parameters:

self - optional, that's held value will be mapped with mapFunc, if present

mapFunc - mapping function, to be applied to value of self, if present

Returns:

optional holding the value of self, mapped to long using mapFunc if value present. Empty optional otherwise.

mapDouble

public static @NonNull OptionalDouble mapDouble(@NonNull OptionalDouble self,
                                                @NonNull DoubleUnaryOperator mapFunc)

Maps the value of self to a double value wrapped into an OptionalDouble, if self holds a value. Returns an empty OptionalDouble otherwise.

Parameters:

self - optional, that's held value will be mapped with mapFunc, if present

mapFunc - mapping function, to be applied to value of self, if present

Returns:

optional holding the value of self, mapped to long using mapFunc if value present. Empty optional otherwise.

flatMapDouble

public static @NonNull OptionalDouble flatMapDouble(@NonNull OptionalDouble self,
                                                    @NonNull DoubleFunction<OptionalDouble> mapFunc)

Maps the value of self to an OptionalDouble using mapFunc, if self has a present value. If self is empty, this method returns an empty OptionalDouble

Parameters:

self - possibly holding value to be mapped with mapFunc

mapFunc - mapping function, used on value of self if a value is present.

Returns:

optional either holding result of mapFunc applied to value of self if value is present, otherwise returning empty optional.

asIterable

public static @NonNull DoubleIterable asIterable(@NonNull OptionalDouble self)

Returns a DoubleIterable that either provides the one value present in self, or an DoubleIterable providing no value if self is empty.

Parameters:

self - optional that's value (if present) will be provided via the returned iterable.

Returns:

DoubleIterable providing one value taken from self or no value, if self is empty.

iterator

public static @NonNull PrimitiveIterator.OfDouble iterator(@NonNull OptionalDouble self)

Returns an PrimitiveIterable.OfDouble that either provides the one value present in self, or an PrimitiveIterable.OfDouble providing no value if self is empty.

Parameters:

self - optional that's value (if present) will be provided via the returned iterator.

Returns:

PrimitiveIterable.OfDouble providing one value taken from self or no value, if self is empty.

toSet

@Pure
public static @NonNull Set<Double> toSet(@NonNull OptionalDouble self)

Returns an immutable set that either contains the value, held by the optional, or an empty set, if the optional is empty.

Parameters:

self - Optional value is read from

Returns:

Set containing the value held by the input optional, or an empty set if the input optional is empty.

stream

public static @NonNull DoubleStream stream(@NonNull OptionalDouble self)

This extension function returns a stream of a single element if the given optional self contains a value, or no element if the optional is empty.

Parameters:

self - the optional providing the value for the Stream provided

Returns:

Stream providing either zero or one value, depending on parameter self

ifPresentOrElse

public static void ifPresentOrElse(OptionalDouble self,
                                   DoubleConsumer action,
                                   Runnable emptyAction)

Will call action with the value held by self if it is not empty. Otherwise will call emptyAction.

Parameters:

self - optional to be checked for value.

action - to be called with value of opt if it is not empty.

emptyAction - to be called if opt is empty.

operator_or

public static @NonNull OptionalDouble operator_or(@NonNull OptionalDouble self,
                                                  @NonNull Supplier<? extends OptionalDouble> alternativeSupplier)

Operator that will be de-sugared to call to OptionalIntExtensions.or(self,alternative).

Parameters:

self - optional to be checked if empty. If not, this value will be returned from operator.

alternativeSupplier - will be called to get return value if self is empty.

Returns:

self, if it is not empty, otherwise returns value supplied by alternativeSupplier.

or

public static @NonNull OptionalDouble or(@NonNull OptionalDouble self,
                                         @NonNull Supplier<? extends OptionalDouble> alternativeSupplier)

This method will either return self if it is not empty, or otherwise the value supplied by alternative.

Parameters:

self - optional to be checked if empty. If not, this value will be returned from operator.

alternativeSupplier - will be called to get return value if self is empty.

Returns:

self, if it is not empty, otherwise returns value supplied by alternativeSupplier.