Module io.helidon.common.mapper

Package io.helidon.common.mapper

Interface Value<T>

Type Parameters:

T - type of the value

All Known Subinterfaces:

ConfigValue<T>, ConfigValue<T>, DbColumn, Header, HeaderWriteable, OptionalValue<T>

All Known Implementing Classes:

ContentDisposition, DbColumnBase, MongoDbColumn

public interface Value<T>

A typed value with support for mapping (conversion) to other types. For values not backed by an data, see OptionalValue.

Method Summary

Modifier and Type	Method	Description
<N> Value<N>	as(GenericType<N> type)	Convert this value to a different type using a mapper.
<N> Value<N>	as(Class<N> type)	Convert this value to a different type using a mapper.
<N> Value<N>	as(Function<? super T,? extends N> mapper)	Convert this Value to a different type using a mapper function.
Value<Boolean>	asBoolean()	Boolean typed value.
Value<Double>	asDouble()	Double typed value.
Value<Integer>	asInt()	Integer typed value.
Value<Long>	asLong()	Long typed value.
Optional<T>	asOptional()	Typed value as Optional.
Value<String>	asString()	String typed value.
static <T> Value<T>	create(MapperManager mapperManager, String name, T value, GenericType<T> type, String... qualifiers)	Create a value backed by data.
static <T> Value<T>	create(MapperManager mapperManager, String name, T value, String... qualifiers)	Create a value backed by data.
default Optional<T>	filter(Predicate<? super T> predicate)	If a value is present, and the value matches the given predicate, return an Optional describing the value, otherwise return an empty Optional.
default <U> Optional<U>	flatMap(Function<? super T,Optional<? extends U>> mapper)	Apply the provided Optional-bearing mapping function to this value, return that result.
T	get()	Typed value.
default <N> N	get(GenericType<N> type)	Convert this value to a different type using a mapper.
default <N> N	get(Class<N> type)	Convert this value to a different type using a mapper.
default boolean	getBoolean()	Boolean typed value.
default double	getDouble()	Double typed value.
default int	getInt()	Integer typed value.
default long	getLong()	Long typed value.
default String	getString()	String typed value.
String	name()	Name of this value, to potentially troubleshoot the source of it.
default Stream<T>	stream()	If a value is present, returns a sequential Stream containing only that value, otherwise returns an empty Stream.

Method Details

create

static <T> Value<T> create(MapperManager mapperManager,
 String name,
 T value,
 String... qualifiers)

Create a value backed by data. The type of the value is "guessed" from the instance provided.

Type Parameters:

T - type of the value

Parameters:

mapperManager - mapper manager to use for mapping types

name - name of the value

value - value, must not be null

qualifiers - qualifiers of the mapper

Returns:

a value backed by data

create

static <T> Value<T> create(MapperManager mapperManager,
 String name,
 T value,
 GenericType<T> type,
 String... qualifiers)

Create a value backed by data.

Type Parameters:

T - type of the value

Parameters:

mapperManager - mapper manager to use for mapping types

name - name of the value

value - value, must not be null

type - a more precise type that could be guessed form an instance

qualifiers - qualifiers of the mapper

Returns:

a value backed by data

name

String name()

Name of this value, to potentially troubleshoot the source of it.

Returns:

name of this value, such as "QueryParam("param-name")"

get

T get()

Typed value.

Returns:

direct value

get

default <N> N get(Class<N> type)
           throws MapperException,
NoSuchElementException

Convert this value to a different type using a mapper.

Type Parameters:

N - type we expect

Parameters:

type - type to convert to

Returns:

converted value

Throws:

MapperException - in case the value cannot be converted

NoSuchElementException - in case the value does not exist

get

default <N> N get(GenericType<N> type)
           throws MapperException,
NoSuchElementException

Convert this value to a different type using a mapper.

Type Parameters:

N - type we expect

Parameters:

type - type to convert to

Returns:

converted value

Throws:

MapperException

NoSuchElementException

as

<N> Value<N> as(Class<N> type)
         throws MapperException

Convert this value to a different type using a mapper.

Type Parameters:

N - type we expect

Parameters:

type - type to convert to

Returns:

converted value

Throws:

MapperException - in case the value cannot be converted

as

<N> Value<N> as(GenericType<N> type)
         throws MapperException

Convert this value to a different type using a mapper.

Type Parameters:

N - type we expect

Parameters:

type - type to convert to

Returns:

converted value

Throws:

MapperException

as

<N> Value<N> as(Function<? super T,? extends N> mapper)

Convert this Value to a different type using a mapper function.

Type Parameters:

N - type of the returned Value

Parameters:

mapper - mapper to map the type of this Value to a type of the returned Value

Returns:

a new value with the new type

asOptional

Optional<T> asOptional()
                throws MapperException

Typed value as Optional. Returns a empty if this value does not have a backing value present. As this class implements all methods of Optional, this is only a utility method if an actual Optional instance is needed (Optional itself is {code final}).

Returns:

value as Optional, empty in case the value does not have a direct value

Throws:

MapperException - in case the value cannot be converted to the expected type

See Also:

• get()

filter

default Optional<T> filter(Predicate<? super T> predicate)

If a value is present, and the value matches the given predicate, return an Optional describing the value, otherwise return an empty Optional.

Parameters:

predicate - a predicate to apply to the value, if present

Returns:

an Optional describing the value of this Optional if a value is present and the value matches the given predicate, otherwise an empty Optional

Throws:

NullPointerException - if the predicate is null

See Also:

• Optional.filter(java.util.function.Predicate)

flatMap

default <U> Optional<U> flatMap(Function<? super T,Optional<? extends U>> mapper)

Apply the provided Optional-bearing mapping function to this value, return that result.

Type Parameters:

U - The type parameter to the Optional returned by

Parameters:

mapper - a mapping function to apply to the value, if present the mapping function

Returns:

the result of applying an Optional-bearing mapping function to this value

Throws:

NullPointerException - if the mapping function is null or returns a null result

See Also:

• Optional.flatMap(java.util.function.Function)

stream

default Stream<T> stream()

If a value is present, returns a sequential Stream containing only that value, otherwise returns an empty Stream.

Returns:

the optional value as a Stream

asBoolean

Value<Boolean> asBoolean()

Boolean typed value.

Returns:

typed value

getBoolean

default boolean getBoolean()

Boolean typed value.

Returns:

boolean value

asString

Value<String> asString()

String typed value.

Returns:

typed value

getString

default String getString()

String typed value.

Returns:

string value

asInt

Value<Integer> asInt()

Integer typed value.

Returns:

typed value

getInt

default int getInt()

Integer typed value.

Returns:

integer value

asLong

Value<Long> asLong()

Long typed value.

Returns:

typed value

getLong

default long getLong()

Long typed value.

Returns:

long value

asDouble

Value<Double> asDouble()

Double typed value.

Returns:

typed value

getDouble

default double getDouble()

Double typed value.

Returns:

double value