org.jdbi.v3.core.collector

Class OptionalCollectors

java.lang.Object

org.jdbi.v3.core.collector.OptionalCollectors

public class OptionalCollectors
extends Object

Factory methods for collectors of optional types.

Method Summary

Modifier and Type	Method and Description
static <T> Collector<T,?,Optional<T>>	toOptional() Returns a Collector that accumulates 0 or 1 input elements into an Optional<T>.
static <T,O> Collector<T,?,O>	toOptional(Supplier<O> empty, Function<T,O> factory) Returns a Collector that accumulates 0 or 1 input elements into an arbitrary optional-style container type.
static Collector<Double,?,OptionalDouble>	toOptionalDouble() Returns a Collector that accumulates 0 or 1 input Double elements into an OptionalDouble.
static Collector<Integer,?,OptionalInt>	toOptionalInt() Returns a Collector that accumulates 0 or 1 input Integer elements into an OptionalInt.
static Collector<Long,?,OptionalLong>	toOptionalLong() Returns a Collector that accumulates 0 or 1 input Long elements into an OptionalLong.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

toOptional

public static <T> Collector<T,?,Optional<T>> toOptional()

Returns a Collector that accumulates 0 or 1 input elements into an Optional<T>. The returned collector will throw IllegalStateException whenever 2 or more elements are present in a stream. Null elements are mapped to Optional.empty().

Type Parameters:

T - the collected type

Returns:

a Collector which collects 0 or 1 input elements into an Optional<T>.

toOptional

public static <T,O> Collector<T,?,O> toOptional(Supplier<O> empty,
                                                Function<T,O> factory)

Returns a Collector that accumulates 0 or 1 input elements into an arbitrary optional-style container type. The returned collector will throw IllegalStateException whenever 2 or more elements are present in a stream. Null elements are mapped to an empty container.

Type Parameters:

T - The optional element type.

O - The optional type, which may incorporate the T generic parameter e.g. Optional<T>.

Parameters:

empty - Supplies an instance of the optional type with no value.

factory - Returns an instance of the optional type with the input parameter as the value.

Returns:

a Collector which collects 0 or 1 input elements into an arbitrary optional-style container type.

toOptionalDouble

public static Collector<Double,?,OptionalDouble> toOptionalDouble()

Returns a Collector that accumulates 0 or 1 input Double elements into an OptionalDouble. The returned collector will throw IllegalStateException whenever 2 or more elements are present in a stream. Null elements are mapped to OptionalDouble.empty().

Returns:

a Collector which collects 0 or 1 input @{code Double} elements into an OptionalDouble.

toOptionalInt

public static Collector<Integer,?,OptionalInt> toOptionalInt()

Returns a Collector that accumulates 0 or 1 input Integer elements into an OptionalInt. The returned collector will throw IllegalStateException whenever 2 or more elements are present in a stream. Null elements are mapped to OptionalInt.empty().

Returns:

a Collector which collects 0 or 1 input Integer elements into an OptionalInt.

toOptionalLong

public static Collector<Long,?,OptionalLong> toOptionalLong()

Returns a Collector that accumulates 0 or 1 input Long elements into an OptionalLong. The returned collector will throw IllegalStateException whenever 2 or more elements are present in a stream. Null elements are mapped to OptionalLong.empty().

Returns:

a Collector which collects 0 or 1 input @{code Long} elements into an OptionalLong.