io.vavr.control

Interface Validation<E,T>

Type Parameters:

E - value type in the case of invalid

T - value type in the case of valid

All Superinterfaces:

java.lang.Iterable<T>, java.io.Serializable, Value<T>

All Known Implementing Classes:

Validation.Invalid, Validation.Valid

public interface Validation<E,T>
extends Value<T>, java.io.Serializable

An implementation similar to scalaz's Validation control.

The Validation type is different from a Monad type, it is an applicative functor. Whereas a Monad will short circuit after the first error, the applicative functor will continue on, accumulating ALL errors. This is especially helpful in cases such as validation, where you want to know all the validation errors that have occurred, not just the first one.

 
 Validation construction:

 Valid:
 Validation<String,Integer> valid = Validation.valid(5);

 Invalid:
 Validation<List<String>,Integer> invalid = Validation.invalid(List.of("error1","error2"));

 Validation combination:

 Validation<String,String> valid1 = Validation.valid("John");
 Validation<String,Integer> valid2 = Validation.valid(5);
 Validation<String,Option<String>> valid3 = Validation.valid(Option.of("123 Fake St."));
 Function3<String,Integer,Option<String>,Person> f = ...;

 Validation<List<String>,String> result = valid1.combine(valid2).ap((name,age) -> "Name: "+name+" Age: "+age);
 Validation<List<String>,Person> result2 = valid1.combine(valid2).combine(valid3).ap(f);

 Another form of combining validations:

 Validation<List<String>,Person> result3 = Validation.combine(valid1, valid2, valid3).ap(f);
 
 

Author:

Eric Nelson

See Also:

Validation

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	Validation.Builder<E,T1,T2>
static class	Validation.Builder3<E,T1,T2,T3>
static class	Validation.Builder4<E,T1,T2,T3,T4>
static class	Validation.Builder5<E,T1,T2,T3,T4,T5>
static class	Validation.Builder6<E,T1,T2,T3,T4,T5,T6>
static class	Validation.Builder7<E,T1,T2,T3,T4,T5,T6,T7>
static class	Validation.Builder8<E,T1,T2,T3,T4,T5,T6,T7,T8>
static class	Validation.Invalid<E,T> An invalid Validation
static class	Validation.Valid<E,T> A valid Validation

Field Summary

Fields

Modifier and Type	Field and Description
static long	serialVersionUID

Method Summary

Modifier and Type	Method and Description
default <U> Validation<Seq<E>,U>	ap(Validation<Seq<E>,? extends java.util.function.Function<? super T,? extends U>> validation)
default <E2,T2> Validation<E2,T2>	bimap(java.util.function.Function<? super E,? extends E2> errorMapper, java.util.function.Function<? super T,? extends T2> valueMapper) Whereas map only performs a mapping on a valid Validation, and mapError performs a mapping on an invalid Validation, bimap allows you to provide mapping actions for both, and will give you the result based on what type of Validation this is.
static <E,T1,T2> Validation.Builder<E,T1,T2>	combine(Validation<E,T1> validation1, Validation<E,T2> validation2) Combines two Validations into a Validation.Builder.
static <E,T1,T2,T3> Validation.Builder3<E,T1,T2,T3>	combine(Validation<E,T1> validation1, Validation<E,T2> validation2, Validation<E,T3> validation3) Combines three Validations into a Validation.Builder3.
static <E,T1,T2,T3,T4> Validation.Builder4<E,T1,T2,T3,T4>	combine(Validation<E,T1> validation1, Validation<E,T2> validation2, Validation<E,T3> validation3, Validation<E,T4> validation4) Combines four Validations into a Validation.Builder4.
static <E,T1,T2,T3,T4,T5> Validation.Builder5<E,T1,T2,T3,T4,T5>	combine(Validation<E,T1> validation1, Validation<E,T2> validation2, Validation<E,T3> validation3, Validation<E,T4> validation4, Validation<E,T5> validation5) Combines five Validations into a Validation.Builder5.
static <E,T1,T2,T3,T4,T5,T6> Validation.Builder6<E,T1,T2,T3,T4,T5,T6>	combine(Validation<E,T1> validation1, Validation<E,T2> validation2, Validation<E,T3> validation3, Validation<E,T4> validation4, Validation<E,T5> validation5, Validation<E,T6> validation6) Combines six Validations into a Validation.Builder6.
static <E,T1,T2,T3,T4,T5,T6,T7> Validation.Builder7<E,T1,T2,T3,T4,T5,T6,T7>	combine(Validation<E,T1> validation1, Validation<E,T2> validation2, Validation<E,T3> validation3, Validation<E,T4> validation4, Validation<E,T5> validation5, Validation<E,T6> validation6, Validation<E,T7> validation7) Combines seven Validations into a Validation.Builder7.
static <E,T1,T2,T3,T4,T5,T6,T7,T8> Validation.Builder8<E,T1,T2,T3,T4,T5,T6,T7,T8>	combine(Validation<E,T1> validation1, Validation<E,T2> validation2, Validation<E,T3> validation3, Validation<E,T4> validation4, Validation<E,T5> validation5, Validation<E,T6> validation6, Validation<E,T7> validation7, Validation<E,T8> validation8) Combines eight Validations into a Validation.Builder8.
default <U> Validation.Builder<E,T,U>	combine(Validation<E,U> validation) Combines two Validations to form a Validation.Builder, which can then be used to perform further combines, or apply a function to it in order to transform the Validation.Builder into a Validation.
boolean	equals(java.lang.Object o) Clarifies that values have a proper equals() method implemented.
default Option<Validation<E,T>>	filter(java.util.function.Predicate<? super T> predicate)
default <U> Validation<E,U>	flatMap(java.util.function.Function<? super T,? extends Validation<E,? extends U>> mapper)
default <U> U	fold(java.util.function.Function<? super E,? extends U> fInvalid, java.util.function.Function<? super T,? extends U> fValid) Performs the action in fInvalid on error if this is an Invalid, or fValid on value if this is a Valid.
default void	forEach(java.util.function.Consumer<? super T> action) Performs the given action for the value contained in Valid, or do nothing if this is an Invalid.
static <E,T> Validation<E,T>	fromEither(Either<E,T> either) Creates a Validation of an Either.
T	get() Gets the value of this Validation if is a Valid or throws if this is an Invalid.
E	getError() Gets the error of this Validation if is an Invalid or throws if this is a Valid
default T	getOrElseGet(java.util.function.Function<? super E,? extends T> other) Gets the value if it is a Valid or an value calculated from the error
int	hashCode() Clarifies that values have a proper hashCode() method implemented.
static <E,T> Validation<E,T>	invalid(E error) Creates an Validation.Invalid that contains the given error.
default boolean	isAsync() A Validation's value is computed synchronously.
default boolean	isEmpty() Checks, this Value is empty, i.e.
boolean	isInvalid() Check whether this is of type Invalid
default boolean	isLazy() A Validation's value is computed eagerly.
default boolean	isSingleValued() States whether this is a single-valued type.
boolean	isValid() Check whether this is of type Valid
default Iterator<T>	iterator() Returns a rich io.vavr.collection.Iterator.
default <U> Validation<E,U>	map(java.util.function.Function<? super T,? extends U> f) Maps the underlying value to a different component type.
default <U> Validation<U,T>	mapError(java.util.function.Function<? super E,? extends U> f) Applies a function f to the error of this Validation if this is an Invalid.
static <E,T> Validation<E,T>	narrow(Validation<? extends E,? extends T> validation) Narrows a widened Validation<? extends E, ? extends T> to Validation<E, T> by performing a type-safe cast.
default Validation<E,T>	orElse(java.util.function.Supplier<Validation<? extends E,? extends T>> supplier) Returns this Validation if it is valid, otherwise return the result of evaluating supplier.
default Validation<E,T>	orElse(Validation<? extends E,? extends T> other) Returns this Validation if it is valid, otherwise return the alternative.
default Validation<E,T>	peek(java.util.function.Consumer<? super T> action) Performs the given action on the first element if this is an eager implementation.
static <E,T> Validation<Seq<E>,Seq<T>>	sequence(java.lang.Iterable<? extends Validation<Seq<E>,T>> values) Reduces many Validation instances into a single Validation by transforming an Iterable<Validation<? extends T>> into a Validation<Seq<T>>.
default Validation<T,E>	swap() Flip the valid/invalid values for this Validation.
default Either<E,T>	toEither() Returns this as Either.
java.lang.String	toString() Clarifies that values have a proper toString() method implemented.
static <E,T> Validation<E,T>	valid(T value) Creates a Validation.Valid that contains the given value.

Methods inherited from interface io.vavr.Value

collect, collect, contains, corresponds, eq, exists, forAll, getOrElse, getOrElse, getOrElseThrow, getOrElseTry, getOrNull, narrow, out, out, spliterator, stderr, stdout, stringPrefix, toArray, toCharSeq, toCompletableFuture, toEither, toEither, toInvalid, toInvalid, 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, toTry, toTry, toValid, toValid, toValidation, toValidation, toVector

Field Detail

serialVersionUID

static final long serialVersionUID

See Also:

Constant Field Values

Method Detail

valid

static <E,T> Validation<E,T> valid(T value)

Creates a Validation.Valid that contains the given value.

Type Parameters:

E - type of the error

T - type of the given value

Parameters:

value - A value

Returns:

Valid(value)

invalid

static <E,T> Validation<E,T> invalid(E error)

Creates an Validation.Invalid that contains the given error.

Type Parameters:

E - type of the given error

T - type of the value

Parameters:

error - An error

Returns:

Invalid(error)

Throws:

java.lang.NullPointerException - if error is null

fromEither

static <E,T> Validation<E,T> fromEither(Either<E,T> either)

Creates a Validation of an Either.

Type Parameters:

E - type of the given error

T - type of the value

Parameters:

either - An Either

Returns:

A Valid(either.get()) if either is a Right, otherwise Invalid(either.getLeft()).

Throws:

java.lang.NullPointerException - if either is null

sequence

static <E,T> Validation<Seq<E>,Seq<T>> sequence(java.lang.Iterable<? extends Validation<Seq<E>,T>> values)

Reduces many Validation instances into a single Validation by transforming an Iterable<Validation<? extends T>> into a Validation<Seq<T>>.

Type Parameters:

E - value type in the case of invalid

T - value type in the case of valid

Parameters:

values - An iterable of Validation instances.

Returns:

A valid Validation of a sequence of values if all Validation instances are valid or an invalid Validation containing an accumulated List of errors.

Throws:

java.lang.NullPointerException - if values is null

narrow

static <E,T> Validation<E,T> narrow(Validation<? extends E,? extends T> validation)

Narrows a widened Validation<? extends E, ? extends T> to Validation<E, T> by performing a type-safe cast. This is eligible because immutable/read-only collections are covariant.

Type Parameters:

E - type of error

T - type of valid value

Parameters:

validation - A Validation.

Returns:

the given validation instance as narrowed type Validation<E, T>.

combine

static <E,T1,T2> Validation.Builder<E,T1,T2> combine(Validation<E,T1> validation1,
                                                     Validation<E,T2> validation2)

Combines two Validations into a Validation.Builder.

Type Parameters:

E - type of error

T1 - type of first valid value

T2 - type of second valid value

Parameters:

validation1 - first validation

validation2 - second validation

Returns:

an instance of Builder<E,T1,T2>

Throws:

java.lang.NullPointerException - if validation1 or validation2 is null

combine

static <E,T1,T2,T3> Validation.Builder3<E,T1,T2,T3> combine(Validation<E,T1> validation1,
                                                            Validation<E,T2> validation2,
                                                            Validation<E,T3> validation3)

Combines three Validations into a Validation.Builder3.

Type Parameters:

E - type of error

T1 - type of first valid value

T2 - type of second valid value

T3 - type of third valid value

Parameters:

validation1 - first validation

validation2 - second validation

validation3 - third validation

Returns:

an instance of Builder3<E,T1,T2,T3>

Throws:

java.lang.NullPointerException - if validation1, validation2 or validation3 is null

combine

static <E,T1,T2,T3,T4> Validation.Builder4<E,T1,T2,T3,T4> combine(Validation<E,T1> validation1,
                                                                  Validation<E,T2> validation2,
                                                                  Validation<E,T3> validation3,
                                                                  Validation<E,T4> validation4)

Combines four Validations into a Validation.Builder4.

Type Parameters:

E - type of error

T1 - type of first valid value

T2 - type of second valid value

T3 - type of third valid value

T4 - type of fourth valid value

Parameters:

validation1 - first validation

validation2 - second validation

validation3 - third validation

validation4 - fourth validation

Returns:

an instance of Builder3<E,T1,T2,T3,T4>

Throws:

java.lang.NullPointerException - if validation1, validation2, validation3 or validation4 is null

combine

static <E,T1,T2,T3,T4,T5> Validation.Builder5<E,T1,T2,T3,T4,T5> combine(Validation<E,T1> validation1,
                                                                        Validation<E,T2> validation2,
                                                                        Validation<E,T3> validation3,
                                                                        Validation<E,T4> validation4,
                                                                        Validation<E,T5> validation5)

Combines five Validations into a Validation.Builder5.

Type Parameters:

E - type of error

T1 - type of first valid value

T2 - type of second valid value

T3 - type of third valid value

T4 - type of fourth valid value

T5 - type of fifth valid value

Parameters:

validation1 - first validation

validation2 - second validation

validation3 - third validation

validation4 - fourth validation

validation5 - fifth validation

Returns:

an instance of Builder3<E,T1,T2,T3,T4,T5>

Throws:

java.lang.NullPointerException - if validation1, validation2, validation3, validation4 or validation5 is null

combine

static <E,T1,T2,T3,T4,T5,T6> Validation.Builder6<E,T1,T2,T3,T4,T5,T6> combine(Validation<E,T1> validation1,
                                                                              Validation<E,T2> validation2,
                                                                              Validation<E,T3> validation3,
                                                                              Validation<E,T4> validation4,
                                                                              Validation<E,T5> validation5,
                                                                              Validation<E,T6> validation6)

Combines six Validations into a Validation.Builder6.

Type Parameters:

E - type of error

T1 - type of first valid value

T2 - type of second valid value

T3 - type of third valid value

T4 - type of fourth valid value

T5 - type of fifth valid value

T6 - type of sixth valid value

Parameters:

validation1 - first validation

validation2 - second validation

validation3 - third validation

validation4 - fourth validation

validation5 - fifth validation

validation6 - sixth validation

Returns:

an instance of Builder3<E,T1,T2,T3,T4,T5,T6>

Throws:

java.lang.NullPointerException - if validation1, validation2, validation3, validation4, validation5 or validation6 is null

combine

static <E,T1,T2,T3,T4,T5,T6,T7> Validation.Builder7<E,T1,T2,T3,T4,T5,T6,T7> combine(Validation<E,T1> validation1,
                                                                                    Validation<E,T2> validation2,
                                                                                    Validation<E,T3> validation3,
                                                                                    Validation<E,T4> validation4,
                                                                                    Validation<E,T5> validation5,
                                                                                    Validation<E,T6> validation6,
                                                                                    Validation<E,T7> validation7)

Combines seven Validations into a Validation.Builder7.

Type Parameters:

E - type of error

T1 - type of first valid value

T2 - type of second valid value

T3 - type of third valid value

T4 - type of fourth valid value

T5 - type of fifth valid value

T6 - type of sixth valid value

T7 - type of seventh valid value

Parameters:

validation1 - first validation

validation2 - second validation

validation3 - third validation

validation4 - fourth validation

validation5 - fifth validation

validation6 - sixth validation

validation7 - seventh validation

Returns:

an instance of Builder3<E,T1,T2,T3,T4,T5,T6,T7>

Throws:

java.lang.NullPointerException - if validation1, validation2, validation3, validation4, validation5, validation6 or validation7 is null

combine

static <E,T1,T2,T3,T4,T5,T6,T7,T8> Validation.Builder8<E,T1,T2,T3,T4,T5,T6,T7,T8> combine(Validation<E,T1> validation1,
                                                                                          Validation<E,T2> validation2,
                                                                                          Validation<E,T3> validation3,
                                                                                          Validation<E,T4> validation4,
                                                                                          Validation<E,T5> validation5,
                                                                                          Validation<E,T6> validation6,
                                                                                          Validation<E,T7> validation7,
                                                                                          Validation<E,T8> validation8)

Combines eight Validations into a Validation.Builder8.

Type Parameters:

E - type of error

T1 - type of first valid value

T2 - type of second valid value

T3 - type of third valid value

T4 - type of fourth valid value

T5 - type of fifth valid value

T6 - type of sixth valid value

T7 - type of seventh valid value

T8 - type of eighth valid value

Parameters:

validation1 - first validation

validation2 - second validation

validation3 - third validation

validation4 - fourth validation

validation5 - fifth validation

validation6 - sixth validation

validation7 - seventh validation

validation8 - eighth validation

Returns:

an instance of Builder3<E,T1,T2,T3,T4,T5,T6,T7,T8>

Throws:

java.lang.NullPointerException - if validation1, validation2, validation3, validation4, validation5, validation6, validation7 or validation8 is null

isValid

boolean isValid()

Check whether this is of type Valid

Returns:

true if is a Valid, false if is an Invalid

isInvalid

boolean isInvalid()

Check whether this is of type Invalid

Returns:

true if is an Invalid, false if is a Valid

orElse

default Validation<E,T> orElse(Validation<? extends E,? extends T> other)

Returns this Validation if it is valid, otherwise return the alternative.

Parameters:

other - An alternative Validation

Returns:

this Validation if it is valid, otherwise return the alternative.

orElse

default Validation<E,T> orElse(java.util.function.Supplier<Validation<? extends E,? extends T>> supplier)

Returns this Validation if it is valid, otherwise return the result of evaluating supplier.

Parameters:

supplier - An alternative Validation supplier

Returns:

this Validation if it is valid, otherwise return the result of evaluating supplier.

isEmpty

default boolean isEmpty()

Description copied from interface: Value

Checks, this Value is empty, i.e. if the underlying value is absent.

Specified by:

isEmpty in interface Value<T>

Returns:

false, if no underlying value is present, true otherwise.

get

T get()

Gets the value of this Validation if is a Valid or throws if this is an Invalid.

Specified by:

get in interface Value<T>

Returns:

The value of this Validation

Throws:

java.util.NoSuchElementException - if this is an Invalid

getOrElseGet

default T getOrElseGet(java.util.function.Function<? super E,? extends T> other)

Gets the value if it is a Valid or an value calculated from the error

Parameters:

other - a function which converts an error to an alternative value

Returns:

the value, if the underlying Validation is a Valid, or else the alternative value provided by other by applying the error.

getError

E getError()

Gets the error of this Validation if is an Invalid or throws if this is a Valid

Returns:

The error of this Invalid

Throws:

java.lang.RuntimeException - if this is a Valid

toEither

default Either<E,T> toEither()

Returns this as Either.

Returns:

Either.right(get()) if this is valid, otherwise Either.left(getError()).

equals

boolean equals(java.lang.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 java.lang.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 java.lang.Object

Returns:

The hashcode of this object

toString

java.lang.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 java.lang.Object

Returns:

A String representation of this object

forEach

default void forEach(java.util.function.Consumer<? super T> action)

Performs the given action for the value contained in Valid, or do nothing if this is an Invalid.

Specified by:

forEach in interface java.lang.Iterable<T>

Specified by:

forEach in interface Value<T>

Parameters:

action - the action to be performed on the contained value

Throws:

java.lang.NullPointerException - if action is null

fold

default <U> U fold(java.util.function.Function<? super E,? extends U> fInvalid,
                   java.util.function.Function<? super T,? extends U> fValid)

Performs the action in fInvalid on error if this is an Invalid, or fValid on value if this is a Valid. Returns an object of type U.

For example:
Validation<List<String>,String> valid = ...;
Integer i = valid.fold(List::length, String::length);

Type Parameters:

U - the fold result type

Parameters:

fInvalid - the invalid fold operation

fValid - the valid fold operation

Returns:

an instance of type U

Throws:

java.lang.NullPointerException - if fInvalid or fValid is null

swap

default Validation<T,E> swap()

Flip the valid/invalid values for this Validation. If this is a Valid<E,T>, returns Invalid<T,E>. Or if this is an Invalid<E,T>, return a Valid<T,E>.

Returns:

a flipped instance of Validation

map

default <U> Validation<E,U> map(java.util.function.Function<? super T,? extends U> f)

Description copied from interface: Value

Maps the underlying value to a different component type.

Specified by:

map in interface Value<T>

Type Parameters:

U - The new component type

Parameters:

f - A mapper

Returns:

A new value

bimap

default <E2,T2> Validation<E2,T2> bimap(java.util.function.Function<? super E,? extends E2> errorMapper,
                                        java.util.function.Function<? super T,? extends T2> valueMapper)

Whereas map only performs a mapping on a valid Validation, and mapError performs a mapping on an invalid Validation, bimap allows you to provide mapping actions for both, and will give you the result based on what type of Validation this is. Without this, you would have to do something like: validation.map(...).mapError(...);

Type Parameters:

E2 - type of the mapping result if this is an invalid

T2 - type of the mapping result if this is a valid

Parameters:

errorMapper - the invalid mapping operation

valueMapper - the valid mapping operation

Returns:

an instance of Validation<U,R>

Throws:

java.lang.NullPointerException - if invalidMapper or validMapper is null

mapError

default <U> Validation<U,T> mapError(java.util.function.Function<? super E,? extends U> f)

Applies a function f to the error of this Validation if this is an Invalid. Otherwise does nothing if this is a Valid.

Type Parameters:

U - type of the error resulting from the mapping

Parameters:

f - a function that maps the error in this Invalid

Returns:

an instance of Validation<U,T>

Throws:

java.lang.NullPointerException - if mapping operation f is null

ap

default <U> Validation<Seq<E>,U> ap(Validation<Seq<E>,? extends java.util.function.Function<? super T,? extends U>> validation)

combine

default <U> Validation.Builder<E,T,U> combine(Validation<E,U> validation)

Combines two Validations to form a Validation.Builder, which can then be used to perform further combines, or apply a function to it in order to transform the Validation.Builder into a Validation.

Type Parameters:

U - type of the value contained in validation

Parameters:

validation - the validation object to combine this with

Returns:

an instance of Builder

filter

default Option<Validation<E,T>> filter(java.util.function.Predicate<? super T> predicate)

flatMap

default <U> Validation<E,U> flatMap(java.util.function.Function<? super T,? extends Validation<E,? extends U>> mapper)

peek

default Validation<E,T> peek(java.util.function.Consumer<? super T> action)

Description copied from interface: Value

Performs the given action on the first element if this is an eager implementation. Performs the given action on all elements (the first immediately, successive deferred), if this is a lazy implementation.

Specified by:

peek in interface Value<T>

Parameters:

action - The action that will be performed on the element(s).

Returns:

this instance

isAsync

default boolean isAsync()

A Validation's value is computed synchronously.

Specified by:

isAsync in interface Value<T>

Returns:

false

isLazy

default boolean isLazy()

A Validation's value is computed eagerly.

Specified by:

isLazy in interface Value<T>

Returns:

false

isSingleValued

default boolean isSingleValued()

Description copied from interface: Value

States whether this is a single-valued type.

Specified by:

isSingleValued in interface Value<T>

Returns:

true if this is single-valued, false otherwise.

iterator

default Iterator<T> iterator()

Description copied from interface: Value

Returns a rich io.vavr.collection.Iterator.

Specified by:

iterator in interface java.lang.Iterable<T>

Specified by:

iterator in interface Value<T>

Returns:

A new Iterator