com.blazegraph.gremlin.util

Interface Lambdas

public interface Lambdas

Lambda helpers.

Author:

mikepersonick

Method Summary

Modifier and Type	Method and Description
static <T> Predicate<T>	distinctByKey(Function<? super T,Object> keyExtractor) Create a "distinct by property" predicate for filtering.
static <K,V> Collector<Map.Entry<K,V>,?,Map<K,V>>	toMap() Collect an Map.Entry stream into a Map.
static <T,K,V,M extends Map<K,V>> Collector<T,?,M>	toMap(Function<? super T,? extends K> keyMapper, Function<? super T,? extends V> valueMapper, Supplier<M> mapSupplier) This is the missing toMap() method on the Collectors class - specify the key mapper, the value mapper, and the map supplier without having to specify the value merge function.
static <K,V,M extends Map<K,V>> Collector<Map.Entry<K,V>,?,M>	toMap(Supplier<M> mapSupplier) Collect an Map.Entry stream into a Map using the specified map supplier.

Method Detail

distinctByKey

static <T> Predicate<T> distinctByKey(Function<? super T,Object> keyExtractor)

Create a "distinct by property" predicate for filtering. Usage: Stream distinct Person objects by name: persons.stream().filter(distinctByKey(p -> p.getName());

Returns:

predicate (thread-safe)

toMap

static <K,V> Collector<Map.Entry<K,V>,?,Map<K,V>> toMap()

Collect an Map.Entry stream into a Map.

Type Parameters:

K - the type of key in the incoming entry stream

V - the type of value in the incoming entry stream

toMap

static <K,V,M extends Map<K,V>> Collector<Map.Entry<K,V>,?,M> toMap(Supplier<M> mapSupplier)

Collect an Map.Entry stream into a Map using the specified map supplier.

Type Parameters:

K - the type of key in the incoming entry stream

V - the type of value in the incoming entry stream

M - the type of the resulting Map

toMap

static <T,K,V,M extends Map<K,V>> Collector<T,?,M> toMap(Function<? super T,? extends K> keyMapper,
                                                         Function<? super T,? extends V> valueMapper,
                                                         Supplier<M> mapSupplier)

This is the missing toMap() method on the Collectors class - specify the key mapper, the value mapper, and the map supplier without having to specify the value merge function.

Type Parameters:

T - the type of the input elements

K - the output type of the key mapping function

V - the output type of the value mapping function

M - the type of the resulting Map