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);

See Also:: Validation

Nested Class Summary

Nested Classes
Modifier and Type	Interface	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 Description

static long serialVersionUID

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	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 `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`.
`default <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`.
`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> ifInvalid, java.util.function.Function<? super T,? extends U> ifValid)`	Transforms this `Validation` to a value of type `U`.
`default 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`.
`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 it 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(Validation<? extends E,? extends T> other)`	Returns this `Validation` if it is valid, otherwise return the alternative.
`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>`	`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>>`.
`default Validation<T,E>`	`swap()`	Flip the valid/invalid values for this Validation.
`default Either<E,T>`	`toEither()`	Converts this Validation to an `Either`.
`java.lang.String`	`toString()`	Clarifies that values have a proper toString() method implemented.
`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 interface io.vavr.Value
collect, collect, contains, corresponds, eq, exists, forAll, getOrElse, getOrElse, getOrElseThrow, getOrElseTry, getOrNull, 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

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 - 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
```
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
```
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
```
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
```
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<E>

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<E>

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 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
```
default Either<E,T> toEither()
```
Converts this Validation to an 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<E>

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<E>

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<E>

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 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
```
default  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
```
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  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
```
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  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  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<E>

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<E>

Returns:

false

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

Specified by:

isLazy in interface Value<E>

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<E>

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<E>

Specified by:

iterator in interface Value<E>

Returns:

A new Iterator

Interface Validation<E,​T>

Nested Class Summary

Field Summary

Method Summary

Methods inherited from interface io.vavr.Value

Field Detail

serialVersionUID

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

equals

hashCode

toString

forEach

fold

swap

map

bimap

mapError

ap

combine

filter

flatMap

peek

isAsync

isLazy

isSingleValued

iterator

Interface Validation<E,T>