java.lang.Object
- io.vavr.control.Validation<E,T>

Type Parameters:: E - value type in the case of invalid; T - value type in the case of valid

All Implemented Interfaces:: Iterable<T>, Value<T>, java.io.Serializable, java.lang.Iterable<T>

Direct Known Subclasses:: Validation.Invalid, Validation.Valid

public abstract class Validation<E,T>
extends java.lang.Object
implements Iterable<T>, 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);

See Also:: Validation, Serialized Form

Nested Class Summary

Nested Classes
Modifier and Type	Class	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>`	Deprecated. will be removed from the public API
`static class`	`Validation.Valid<E,T>`	Deprecated. will be removed from the public API

Method Summary

Modifier and Type	Method	Description
`<U> Validation<Seq<E>,U>`	`ap(Validation<Seq<E>,? extends java.util.function.Function<? super T,? extends U>> validation)`
`<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 `Validation`s 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 `Validation`s 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 `Validation`s 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 `Validation`s 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 `Validation`s 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 `Validation`s 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 `Validation`s into a `Validation.Builder8`.
`<U> Validation.Builder<E,T,U>`	`combine(Validation<E,U> validation)`	Combines two `Validation`s 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`.
`Option<Validation<E,T>>`	`filter(java.util.function.Predicate<? super T> predicate)`
`<U> Validation<E,U>`	`flatMap(java.util.function.Function<? super T,? extends Validation<E,? extends U>> mapper)`
`<U> U`	`fold(java.util.function.Function<? super E,? extends U> ifInvalid, java.util.function.Function<? super T,? extends U> ifValid)`	Transforms this `Validation` to a value of type `U`.
`void`	`forEach(java.util.function.Consumer<? super T> action)`	Performs the given action for the value contained in `Valid`, or does nothing if this is an `Invalid`.
`static <E,T> Validation<E,T>`	`fromEither(Either<E,T> either)`	Creates a `Validation` of an `Either`.
`static <T> Validation<java.lang.Throwable,T>`	`fromTry(Try<? extends T> t)`	Creates a `Validation` of an `Try`.
`abstract T`	`get()`	Gets the value of this `Validation` if is a `Valid` or throws if this is an `Invalid`.
`abstract E`	`getError()`	Gets the error of this Validation if it is an `Invalid` or throws if this is a `Valid`.
`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.
`static <E,T> Validation<E,T>`	`invalid(E error)`	Creates an `Validation.Invalid` that contains the given `error`.
`boolean`	`isAsync()`	A `Validation`'s value is computed synchronously.
`boolean`	`isEmpty()`	Checks, this `Value` is empty, i.e.
`abstract boolean`	`isInvalid()`	Check whether this is of type `Invalid`
`boolean`	`isLazy()`	A `Validation`'s value is computed eagerly.
`boolean`	`isSingleValued()`	States whether this is a single-valued type.
`abstract boolean`	`isValid()`	Check whether this is of type `Valid`
`Iterator<T>`	`iterator()`	Returns a rich `Iterator` that allows us to perform intermediate, sequential operations known from Vavr's collection library.
`<U> Validation<E,U>`	`map(java.util.function.Function<? super T,? extends U> f)`	Maps the underlying value to a different component type.
`<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.
`Validation<E,T>`	`orElse(Validation<? extends E,? extends T> other)`	Returns this `Validation` if it is valid, otherwise return the alternative.
`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.
`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<? extends Seq<? extends E>,? extends T>> values)`	Reduces many `Validation` instances into a single `Validation` by transforming an `Iterable<Validation<? extends T>>` into a `Validation<Seq<T>>`.
`Validation<T,E>`	`swap()`	Flip the valid/invalid values for this Validation.
`Either<E,T>`	`toEither()`	Converts this Validation to an `Either`.
`static <E,T,U> Validation<Seq<E>,Seq<U>>`	`traverse(java.lang.Iterable<? extends T> values, java.util.function.Function<? super T,? extends Validation<? extends Seq<? extends E>,? extends U>> mapper)`	Maps the values of an iterable to a sequence of mapped values into a single `Validation` by transforming an `Iterable<? extends T>` into a `Validation<Seq<U>>`.
`static <E,T> Validation<E,T>`	`valid(T value)`	Creates a `Validation.Valid` that contains the given `value`.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.vavr.Iterable
to

Methods inherited from interface io.vavr.Value
collect, collect, contains, corresponds, eq, equals, exists, forAll, getOrElse, getOrElse, getOrElseThrow, getOrElseTry, getOrNull, hashCode, 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, toString, toTree, toTree, toTry, toTry, toValid, toValid, toValidation, toValidation, toVector

Method Detail

valid
```
public 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
```
public 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
```
public static <E,T> Validation<E,T> fromEither(Either<E,T> either)
```
Creates a Validation of an Either.

Type Parameters:

E - error type

T - value type

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

fromTry
```
public static <T> Validation<java.lang.Throwable,T> fromTry(Try<? extends T> t)
```
Creates a Validation of an Try.

Type Parameters:

T - type of the valid value

Parameters:

t - A Try

Returns:

A Valid(t.get()) if t is a Success, otherwise Invalid(t.getCause()).

Throws:

java.lang.NullPointerException - if t is null

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

traverse
```
public static <E,T,U> Validation<Seq<E>,Seq> traverse(java.lang.Iterable<? extends T> values,
 java.util.function.Function<? super T,? extends Validation<? extends Seq<? extends E>,? extends U>> mapper)
```
Maps the values of an iterable to a sequence of mapped values into a single Validation by transforming an Iterable<? extends T> into a Validation<Seq>.

Type Parameters:

T - The type of the given values.

E - The mapped error value type.

U - The mapped valid value type.

Parameters:

values - An Iterable of values.

mapper - A mapper of values to Validations

Returns:

A Validation of a Seq of results.

Throws:

java.lang.NullPointerException - if values or f is null.

narrow
```
public 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
```
public 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

public 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

public 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

public 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

public 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

public 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

public 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
```
public abstract boolean isValid()
```
Check whether this is of type Valid

Returns:

true if is a Valid, false if is an Invalid

isInvalid
```
public abstract boolean isInvalid()
```
Check whether this is of type Invalid

Returns:

true if is an Invalid, false if is a Valid

orElse
```
public final 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
```
public final 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
```
public final 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<E>

Returns:

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

get
```
public abstract 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<E>

Returns:

The value of this Validation

Throws:

java.util.NoSuchElementException - if this is an Invalid

getOrElseGet
```
public final 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
```
public abstract E getError()
```
Gets the error of this Validation if it is an Invalid or throws if this is a Valid.

Returns:

The error, if present

Throws:

java.lang.RuntimeException - if this is a Valid

toEither
```
public final Either<E,T> toEither()
```
Converts this Validation to an Either.

Returns:

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

forEach
```
public final void forEach(java.util.function.Consumer<? super T> action)
```
Performs the given action for the value contained in Valid, or does nothing if this is an Invalid.

Specified by:

forEach in interface java.lang.Iterable<E>

Specified by:

forEach in interface Value<E>

Parameters:

action - the action to be performed on the contained value

Throws:

java.lang.NullPointerException - if action is null

fold
```
public final  U fold(java.util.function.Function<? super E,? extends U> ifInvalid,
 java.util.function.Function<? super T,? extends U> ifValid)
```
Transforms this Validation to a value of type U.
Example:
```
 Validation<List<String>, String> valid = ...; 
 int i = valid.fold(List::length, String::length);
 
```
Type Parameters:

U - the fold result type

Parameters:

ifInvalid - an error mapper

ifValid - an mapper for a valid value

Returns:

ifValid.apply(get()) if this is valid, otherwise ifInvalid.apply(getError()).

Throws:

java.lang.NullPointerException - if one of the given mappers ifInvalid or ifValid is null

swap
```
public final 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
```
public final  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<E>

Type Parameters:

U - The new component type

Parameters:

f - A mapper

Returns:

A new value

bimap
```
public final <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
```
public final  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

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

combine
```
public final  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

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

flatMap

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

peek
```
public final 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<E>

Parameters:

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

Returns:

this instance

isAsync
```
public final boolean isAsync()
```
A Validation's value is computed synchronously.

Specified by:

isAsync in interface Value<E>

Returns:

false

isLazy
```
public final boolean isLazy()
```
A Validation's value is computed eagerly.

Specified by:

isLazy in interface Value<E>

Returns:

false

isSingleValued
```
public final boolean isSingleValued()
```
Description copied from interface: Value

States whether this is a single-valued type.

Specified by:

isSingleValued in interface Value<E>

Returns:

true if this is single-valued, false otherwise.

iterator
```
public final Iterator<T> iterator()
```
Description copied from interface: Iterable

Returns a rich Iterator that allows us to perform intermediate, sequential operations known from Vavr's collection library.

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface java.lang.Iterable<E>

Specified by:

iterator in interface Value<E>

Returns:

an Iterator instance (that might be a singleton in the empty case)

Class Validation<E,​T>

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface io.vavr.Iterable

Methods inherited from interface io.vavr.Value

Method Detail

valid

invalid

fromEither

fromTry

sequence

traverse

narrow

combine

combine

combine

combine

combine

combine

combine

isValid

isInvalid

orElse

orElse

isEmpty

get

getOrElseGet

getError

toEither

forEach

fold

swap

map

bimap

mapError

ap

combine

filter

flatMap

peek

isAsync

isLazy

isSingleValued

iterator

Class Validation<E,T>