Option (Vavr 0.10.2 API)

Type Parameters:

T - The type of the optional value.

All Superinterfaces:

Iterable<T>, Serializable, Value<T>

All Known Implementing Classes:

Option.None, Option.Some
```
public interface Option<T>
extends Value<T>, Serializable
```
Replacement for Optional.
Option is a monadic container type which represents an optional value. Instances of Option are either an instance of Option.Some or the singleton Option.None.
Most of the API is taken from Optional. A similar type can be found in Haskell and Scala.

Author:

Daniel Dietrich

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static class`	`Option.None<T>` None is a singleton representation of the undefined `Option`.
`static class`	`Option.Some<T>` Some represents a defined `Option`.

Field Summary

Fields
Modifier and Type Field and Description

static long serialVersionUID

Fields
Modifier and Type	Field and Description
`static long`	`serialVersionUID`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`default <R> Option<R>`	`collect(PartialFunction<? super T,? extends R> partialFunction)` Collects value that is in the domain of the given `partialFunction` by mapping the value to type `R`.
`boolean`	`equals(Object o)` Clarifies that values have a proper equals() method implemented.
`default Option<T>`	`filter(Predicate<? super T> predicate)` Returns `Some(value)` if this is a `Some` and the value satisfies the given predicate.
`default <U> Option<U>`	`flatMap(Function<? super T,? extends Option<? extends U>> mapper)` Maps the value to a new `Option` if this is a `Some`, otherwise returns `None`.
`default <U> U`	`fold(Supplier<? extends U> ifNone, Function<? super T,? extends U> f)` Folds either the `None` or the `Some` side of the Option value.
`T`	`get()` Gets the value if this is a `Some` or throws if this is a `None`.
`default T`	`getOrElse(Supplier<? extends T> supplier)` Returns the value if this is a `Some`, otherwise the `other` value is returned, if this is a `None`.
`default T`	`getOrElse(T other)` Returns the value if this is a `Some` or the `other` value if this is a `None`.
`default <X extends Throwable> T`	`getOrElseThrow(Supplier<X> exceptionSupplier)` Returns the value if this is a `Some`, otherwise throws an exception.
`int`	`hashCode()` Clarifies that values have a proper hashCode() method implemented.
`default boolean`	`isAsync()` An `Option`'s value is computed synchronously.
`default boolean`	`isDefined()` Returns true, if this is `Some`, otherwise false, if this is `None`.
`boolean`	`isEmpty()` Returns true, if this is `None`, otherwise false, if this is `Some`.
`default boolean`	`isLazy()` An `Option`'s value is computed eagerly.
`default boolean`	`isSingleValued()` An `Option` is single-valued.
`default Iterator<T>`	`iterator()` Returns a rich `io.vavr.collection.Iterator`.
`default <U> Option<U>`	`map(Function<? super T,? extends U> mapper)` Maps the value and wraps it in a new `Some` if this is a `Some`, returns `None`.
`static <T> Option<T>`	`narrow(Option<? extends T> option)` Narrows a widened `Option<? extends T>` to `Option<T>` by performing a type-safe cast.
`static <T> Option<T>`	`none()` Returns the single instance of `None`
`static <T> Option<T>`	`of(T value)` Creates a new `Option` of a given value.
`static <T> Option<T>`	`ofOptional(Optional<? extends T> optional)` Wraps a Java Optional to a new Option
`default Option<T>`	`onEmpty(Runnable action)` Runs a Java Runnable passed as parameter if this `Option` is empty.
`default Option<T>`	`orElse(Option<? extends T> other)` Returns this `Option` if it is nonempty, otherwise return the alternative.
`default Option<T>`	`orElse(Supplier<? extends Option<? extends T>> supplier)` Returns this `Option` if it is nonempty, otherwise return the result of evaluating supplier.
`default Option<T>`	`peek(Consumer<? super T> action)` Applies an action to this value, if this option is defined, otherwise does nothing.
`static <T> Option<Seq<T>>`	`sequence(Iterable<? extends Option<? extends T>> values)` Reduces many `Option`s into a single `Option` by transforming an `Iterable<Option<? extends T>>` into a `Option<Seq<T>>`.
`static <T> Option<T>`	`some(T value)` Creates a new `Some` of a given value.
`String`	`toString()` Clarifies that values have a proper toString() method implemented.
`default <U> U`	`transform(Function<? super Option<T>,? extends U> f)` Transforms this `Option`.
`static <T,U> Option<Seq<U>>`	`traverse(Iterable<? extends T> values, Function<? super T,? extends Option<? extends U>> mapper)` Maps the values of an iterable to a sequence of mapped values into a single `Option` by transforming an `Iterable<? extends T>` into a `Option<Seq<U>>`.
`static <T> Option<T>`	`when(boolean condition, Supplier<? extends T> supplier)` Creates `Some` of suppliers value if condition is true, or `None` in other case
`static <T> Option<T>`	`when(boolean condition, T value)` Creates `Some` of value if condition is true, or `None` in other case

Methods inherited from interface io.vavr.Value
collect, collect, contains, corresponds, eq, exists, forAll, forEach, getOrElseTry, getOrNull, narrow, out, out, spliterator, stderr, stdout, stringPrefix, toArray, toCharSeq, toCompletableFuture, toEither, toEither, toInvalid, toInvalid, toJavaArray, toJavaArray, toJavaArray, toJavaCollection, toJavaList, toJavaList, toJavaMap, toJavaMap, toJavaMap, toJavaOptional, toJavaParallelStream, toJavaSet, toJavaSet, toJavaStream, toLeft, toLeft, toLinkedMap, toLinkedMap, toLinkedSet, toList, toMap, toMap, toOption, toPriorityQueue, toPriorityQueue, toQueue, toRight, toRight, toSet, toSortedMap, toSortedMap, toSortedMap, toSortedMap, toSortedSet, toSortedSet, toStream, toTree, toTree, toTry, toTry, toValid, toValid, toValidation, toValidation, toVector

- Field Detail
 - serialVersionUID
```
static final long serialVersionUID
```
 See Also:
 
 Constant Field Values
- Method Detail
 - of
```
static <T> Option<T> of(T value)
```
 Creates a new Option of a given value.
 
 Type Parameters:
 
 T - type of the value
 
 Parameters:
 
 value - A value
 
 Returns:
 
 Some(value) if value is not null, None otherwise
 - sequence
```
static <T> Option<Seq<T>> sequence(Iterable<? extends Option<? extends T>> values)
```
 Reduces many Options into a single Option by transforming an Iterable<Option<? extends T>> into a Option<Seq<T>>. If any of the Options are Option.None, then this returns Option.None.
 
 Type Parameters:
 
 T - type of the Options
 
 Parameters:
 
 values - An Iterable of Options
 
 Returns:
 
 An Option of a Seq of results
 
 Throws:
 
 NullPointerException - if values is null
 - traverse
```
static <T,U> Option<Seq> traverse(Iterable<? extends T> values,
 Function<? super T,? extends Option<? extends U>> mapper)
```
 Maps the values of an iterable to a sequence of mapped values into a single Option by transforming an Iterable<? extends T> into a Option<Seq>.
 
 Type Parameters:
 
 T - The type of the given values.
 
 U - The mapped value type.
 
 Parameters:
 
 values - An Iterable of values.
 
 mapper - A mapper of values to Options
 
 Returns:
 
 A Option of a Seq of results.
 
 Throws:
 
 NullPointerException - if values or f is null.
 - some
```
static <T> Option<T> some(T value)
```
 Creates a new Some of a given value.
 The only difference to of(Object) is, when called with argument null.
```
 
 Option.of(null); // = None
 Option.some(null); // = Some(null)
 
 
```
 Type Parameters:
 
 T - type of the value
 
 Parameters:
 
 value - A value
 
 Returns:
 
 Some(value)
 - none
```
static <T> Option<T> none()
```
 Returns the single instance of None
 
 Type Parameters:
 
 T - component type
 
 Returns:
 
 the single instance of None
 - narrow
```
static <T> Option<T> narrow(Option<? extends T> option)
```
 Narrows a widened Option<? extends T> to Option<T> by performing a type-safe cast. This is eligible because immutable/read-only collections are covariant.
 
 Type Parameters:
 
 T - Component type of the Option.
 
 Parameters:
 
 option - A Option.
 
 Returns:
 
 the given option instance as narrowed type Option<T>.
 - when
```
static <T> Option<T> when(boolean condition,
 Supplier<? extends T> supplier)
```
 Creates Some of suppliers value if condition is true, or None in other case
 
 Type Parameters:
 
 T - type of the optional value
 
 Parameters:
 
 condition - A boolean value
 
 supplier - An optional value supplier, may supply null
 
 Returns:
 
 return Some of supplier's value if condition is true, or None in other case
 
 Throws:
 
 NullPointerException - if the given supplier is null
 - when
```
static <T> Option<T> when(boolean condition,
 T value)
```
 Creates Some of value if condition is true, or None in other case
 
 Type Parameters:
 
 T - type of the optional value
 
 Parameters:
 
 condition - A boolean value
 
 value - An optional value, may be null
 
 Returns:
 
 return Some of value if condition is true, or None in other case
 - ofOptional
```
static <T> Option<T> ofOptional(Optional<? extends T> optional)
```
 Wraps a Java Optional to a new Option
 
 Type Parameters:
 
 T - type of the value
 
 Parameters:
 
 optional - a given optional to wrap in Option
 
 Returns:
 
 Some(optional.get()) if value is Java Optional is present, None otherwise
 - collect
```
default <R> Option<R> collect(PartialFunction<? super T,? extends R> partialFunction)
```
 Collects value that is in the domain of the given partialFunction by mapping the value to type R.
```
 partialFunction.isDefinedAt(value)
 
```
 If the element makes it through that filter, the mapped instance is wrapped in Option
```
 R newValue = partialFunction.apply(value)
 
```
 Type Parameters:
 
 R - The new value type
 
 Parameters:
 
 partialFunction - A function that is not necessarily defined on value of this option.
 
 Returns:
 
 A new Option instance containing value of type R
 
 Throws:
 
 NullPointerException - if partialFunction is null
 - isEmpty
```
boolean isEmpty()
```
 Returns true, if this is None, otherwise false, if this is Some.
 
 Specified by:
 
 isEmpty in interface Value<T>
 
 Returns:
 
 true, if this Option is empty, false otherwise
 - onEmpty
```
default Option<T> onEmpty(Runnable action)
```
 Runs a Java Runnable passed as parameter if this Option is empty.
 
 Parameters:
 
 action - a given Runnable to be run
 
 Returns:
 
 this Option
 - isAsync
```
default boolean isAsync()
```
 An Option's value is computed synchronously.
 
 Specified by:
 
 isAsync in interface Value<T>
 
 Returns:
 
 false
 - isDefined
```
default boolean isDefined()
```
 Returns true, if this is Some, otherwise false, if this is None.
 Please note that it is possible to create new Some(null), which is defined.
 
 Returns:
 
 true, if this Option has a defined value, false otherwise
 - isLazy
```
default boolean isLazy()
```
 An Option's value is computed eagerly.
 
 Specified by:
 
 isLazy in interface Value<T>
 
 Returns:
 
 false
 - isSingleValued
```
default boolean isSingleValued()
```
 An Option is single-valued.
 
 Specified by:
 
 isSingleValued in interface Value<T>
 
 Returns:
 
 true
 - get
```
T get()
```
 Gets the value if this is a Some or throws if this is a None.
 
 Specified by:
 
 get in interface Value<T>
 
 Returns:
 
 the value
 
 Throws:
 
 NoSuchElementException - if this is a None.
 - getOrElse
```
default T getOrElse(T other)
```
 Returns the value if this is a Some or the other value if this is a None.
 Please note, that the other value is eagerly evaluated.
 
 Specified by:
 
 getOrElse in interface Value<T>
 
 Parameters:
 
 other - An alternative value
 
 Returns:
 
 This value, if this Option is defined or the other value, if this Option is empty.
 - orElse
```
default Option<T> orElse(Option<? extends T> other)
```
 Returns this Option if it is nonempty, otherwise return the alternative.
 
 Parameters:
 
 other - An alternative Option
 
 Returns:
 
 this Option if it is nonempty, otherwise return the alternative.
 - orElse
```
default Option<T> orElse(Supplier<? extends Option<? extends T>> supplier)
```
 Returns this Option if it is nonempty, otherwise return the result of evaluating supplier.
 
 Parameters:
 
 supplier - An alternative Option supplier
 
 Returns:
 
 this Option if it is nonempty, otherwise return the result of evaluating supplier.
 - getOrElse
```
default T getOrElse(Supplier<? extends T> supplier)
```
 Returns the value if this is a Some, otherwise the other value is returned, if this is a None.
 Please note, that the other value is lazily evaluated.
 
 Specified by:
 
 getOrElse in interface Value<T>
 
 Parameters:
 
 supplier - An alternative value supplier
 
 Returns:
 
 This value, if this Option is defined or the other value, if this Option is empty.
 - getOrElseThrow
```
default <X extends Throwable> T getOrElseThrow(Supplier<X> exceptionSupplier)
 throws X extends Throwable
```
 Returns the value if this is a Some, otherwise throws an exception.
 
 Specified by:
 
 getOrElseThrow in interface Value<T>
 
 Type Parameters:
 
 X - A throwable
 
 Parameters:
 
 exceptionSupplier - An exception supplier
 
 Returns:
 
 This value, if this Option is defined, otherwise throws X
 
 Throws:
 
 X - a throwable
 
 X extends Throwable
 - filter
```
default Option<T> filter(Predicate<? super T> predicate)
```
 Returns Some(value) if this is a Some and the value satisfies the given predicate. Otherwise None is returned.
 
 Parameters:
 
 predicate - A predicate which is used to test an optional value
 
 Returns:
 
 Some(value) or None as specified
 - flatMap
```
default  Option flatMap(Function<? super T,? extends Option<? extends U>> mapper)
```
 Maps the value to a new Option if this is a Some, otherwise returns None.
 
 Type Parameters:
 
 U - Component type of the resulting Option
 
 Parameters:
 
 mapper - A mapper
 
 Returns:
 
 a new Option
 - map
```
default  Option map(Function<? super T,? extends U> mapper)
```
 Maps the value and wraps it in a new Some if this is a Some, returns None.
 
 Specified by:
 
 map in interface Value<T>
 
 Type Parameters:
 
 U - The new value type
 
 Parameters:
 
 mapper - A value mapper
 
 Returns:
 
 a new Some containing the mapped value if this Option is defined, otherwise None, if this is empty.
 - fold
```
default  U fold(Supplier<? extends U> ifNone,
 Function<? super T,? extends U> f)
```
 Folds either the None or the Some side of the Option value.
 
 Type Parameters:
 
 U - type of the folded value
 
 Parameters:
 
 ifNone - maps the left value if this is a None
 
 f - maps the value if this is a Some
 
 Returns:
 
 A value of type U
 - peek
```
default Option<T> peek(Consumer<? super T> action)
```
 Applies an action to this value, if this option is defined, otherwise does nothing.
 
 Specified by:
 
 peek in interface Value<T>
 
 Parameters:
 
 action - An action which can be applied to an optional value
 
 Returns:
 
 this Option
 - transform
```
default  U transform(Function<? super Option<T>,? extends U> f)
```
 Transforms this Option.
 
 Type Parameters:
 
 U - Type of transformation result
 
 Parameters:
 
 f - A transformation
 
 Returns:
 
 An instance of type U
 
 Throws:
 
 NullPointerException - if f is null
 - iterator
```
default Iterator<T> iterator()
```
 Description copied from interface: Value
 
 Returns a rich io.vavr.collection.Iterator.
 
 Specified by:
 
 iterator in interface Iterable<T>
 
 Specified by:
 
 iterator in interface Value<T>
 
 Returns:
 
 A new Iterator
 - equals
```
boolean equals(Object o)
```
 Description copied from interface: Value
 
 Clarifies that values have a proper equals() method implemented.
 See Object.equals(Object).
 
 Specified by:
 
 equals in interface Value<T>
 
 Overrides:
 
 equals in class Object
 
 Parameters:
 
 o - An object
 
 Returns:
 
 true, if this equals o, false otherwise
 - hashCode
```
int hashCode()
```
 Description copied from interface: Value
 
 Clarifies that values have a proper hashCode() method implemented.
 See Object.hashCode().
 
 Specified by:
 
 hashCode in interface Value<T>
 
 Overrides:
 
 hashCode in class Object
 
 Returns:
 
 The hashcode of this object
 - toString
```
String toString()
```
 Description copied from interface: Value
 
 Clarifies that values have a proper toString() method implemented.
 See Object.toString().
 
 Specified by:
 
 toString in interface Value<T>
 
 Overrides:
 
 toString in class Object
 
 Returns:
 
 A String representation of this object

Interface Option<T>

Nested Class Summary

Field Summary

Method Summary

Methods inherited from interface io.vavr.Value

Field Detail

serialVersionUID

Method Detail

of

sequence

traverse

some

none

narrow

when

when

ofOptional

collect

isEmpty

onEmpty

isAsync

isDefined

isLazy

isSingleValued

get

getOrElse

orElse

orElse

getOrElse

getOrElseThrow

filter

flatMap

map

fold

peek

transform

iterator

equals

hashCode

toString