Package org.apache.wayang.core.util

Class WayangCollections

java.lang.Object

org.apache.wayang.core.util.WayangCollections

public class WayangCollections
extends Object

Utilities to operate Collections.

Method Summary

Modifier and Type	Method	Description
static <C extends Collection<T>, T> C	add(C collection, T element)	Adds an element to a Collection and returns the Collection.
static <T, C extends Collection<T>> C	addAll(C collection, C elements)	Adds elements to a Collection and returns the Collection.
static <T, C extends Collection<T>> C	asCollection(Iterable<T> iterable, Supplier<C> collectionFactory)	Provides the given iterable as Collection.
static <T> List<T>	asList(Collection<T> collection)	Provides the given collection as List, thereby checking if it is already a List.
static <T> Set<T>	asSet(Iterable<T> iterable)	Provides the given iterable as Set, thereby checking if it is already a Set.
static <T> Set<T>	asSet(Collection<T> collection)	Provides the given collection as Set, thereby checking if it is already a Set.
static <T> Set<T>	asSet(T... values)	Provides the given values as Set.
static <K, V> Map<K,V>	createMap(Tuple<K,V>... keyValuePairs)
static <T> ArrayList<T>	createNullFilledArrayList(int k)	Creates an ArrayList that is filled with k nulls.
static <T> Collection<List<T>>	createPowerList(Collection<T> base)	Creates the power list of the given base (akin to power sets of sets).
static <T> Collection<List<T>>	createPowerList(Collection<T> base, int maxElements)	Creates the power list of the given base (akin to power sets of sets).
static <T> T	getAny(Iterable<T> iterable)	Return any element from the iterable.
static <T> Optional<T>	getAnyOptional(Iterable<T> iterable)	Return any element from the iterable if it exists.
static <T> T	getSingle(Collection<T> collection)	Validate that there is only a single element in the collection and return it.
static <T> T	getSingleOrNull(Collection<T> collection)	Validate that there is at most one element in the collection and return it (or null otherwise).
static <S, T> List<T>	map(List<S> list, BiFunction<Integer,S,T> mapFunction)	Return a new List with mapped values.
static <S, T> List<T>	map(List<S> list, Function<S,T> mapFunction)	Return a new List with mapped values.
static <K, V> void	put(Map<K,Collection<V>> map, K key, V value)
static <T> Iterable<List<T>>	streamedCrossProduct(List<? extends Iterable<T>> iterables)	Returns an Iterable that iterates the cross product of the given iterables.

Methods inherited from class java.lang.Object

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

Method Details

put

public static <K,
V> void put(Map<K,Collection<V>> map,
 K key,
 V value)

asSet

public static <T> Set<T> asSet(Collection<T> collection)

Provides the given collection as Set, thereby checking if it is already a Set.

asSet

public static <T> Set<T> asSet(Iterable<T> iterable)

Provides the given iterable as Set, thereby checking if it is already a Set.

asSet

public static <T> Set<T> asSet(T... values)

Provides the given values as Set.

asList

public static <T> List<T> asList(Collection<T> collection)

Provides the given collection as List, thereby checking if it is already a List.

asCollection

public static <T,
C extends Collection<T>> C asCollection(Iterable<T> iterable,
 Supplier<C> collectionFactory)

Provides the given iterable as Collection.

getSingle

public static <T> T getSingle(Collection<T> collection)

Validate that there is only a single element in the collection and return it.

getSingleOrNull

public static <T> T getSingleOrNull(Collection<T> collection)

Validate that there is at most one element in the collection and return it (or null otherwise).

getAny

public static <T> T getAny(Iterable<T> iterable)

Return any element from the iterable.

getAnyOptional

public static <T> Optional<T> getAnyOptional(Iterable<T> iterable)

Return any element from the iterable if it exists.

add

public static <C extends Collection<T>,
T> C add(C collection,
 T element)

Adds an element to a Collection and returns the Collection.

Parameters:

collection - to which the element should be added

element - that should be added to the collection

Returns:

the collection

addAll

public static <T,
C extends Collection<T>> C addAll(C collection,
 C elements)

Adds elements to a Collection and returns the Collection.

Parameters:

collection - to which the element should be added

elements - that should be added to the collection

Returns:

the collection

map

public static <S,
T> List<T> map(List<S> list,
 Function<S,T> mapFunction)

Return a new List with mapped values.

map

public static <S,
T> List<T> map(List<S> list,
 BiFunction<Integer,S,T> mapFunction)

Return a new List with mapped values.

streamedCrossProduct

public static <T> Iterable<List<T>> streamedCrossProduct(List<? extends Iterable<T>> iterables)

Returns an Iterable that iterates the cross product of the given iterables.

Parameters:

iterables - should be iterable multiple times

createNullFilledArrayList

public static <T> ArrayList<T> createNullFilledArrayList(int k)

Creates an ArrayList that is filled with k nulls.

createPowerList

public static <T> Collection<List<T>> createPowerList(Collection<T> base)

Creates the power list of the given base (akin to power sets of sets).

createPowerList

public static <T> Collection<List<T>> createPowerList(Collection<T> base,
 int maxElements)

Creates the power list of the given base (akin to power sets of sets).

Parameters:

maxElements - maximum number of elements in the Lists in the power list

createMap

public static <K,
V> Map<K,V> createMap(Tuple<K,V>... keyValuePairs)