DistributedCollectors (hazelcast-jet-all 0.4 API)

java.lang.Object
- com.hazelcast.jet.stream.DistributedCollectors

```
public abstract class DistributedCollectors
extends Object
```
Implementations of DistributedCollector that implement various useful reduction operations, such as accumulating elements into collections, summarizing elements according to various criteria, etc.

Constructor Summary

Constructors
Constructor and Description

DistributedCollectors()

Constructors
Constructor and Description
`DistributedCollectors()`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static <T> DistributedCollector<T,?,Double>`	`averagingDouble(DistributedToDoubleFunction<? super T> mapper)` Returns a `DistributedCollector` that produces the arithmetic mean of a double-valued function applied to the input elements.
`static <T> DistributedCollector<T,?,Double>`	`averagingInt(DistributedToIntFunction<? super T> mapper)` Returns a `DistributedCollector` that produces the arithmetic mean of an integer-valued function applied to the input elements.
`static <T> DistributedCollector<T,?,Double>`	`averagingLong(DistributedToLongFunction<? super T> mapper)` Returns a `DistributedCollector` that produces the arithmetic mean of a long-valued function applied to the input elements.
`static <T,A,R,RR> DistributedCollector<T,A,RR>`	`collectingAndThen(DistributedCollector<T,A,R> downstream, DistributedFunction<R,RR> finisher)` Adapts a `DistributedCollector` to perform an additional finishing transformation.
`static <T> DistributedCollector<T,?,Long>`	`counting()` Returns a `DistributedCollector` accepting elements of type `T` that counts the number of input elements.
`static <T,K> DistributedCollector<T,?,Map<K,List<T>>>`	`groupingBy(DistributedFunction<? super T,? extends K> classifier)` Returns a `DistributedCollector` implementing a "group by" operation on input elements of type `T`, grouping elements according to a classification function, and returning the results in a `Map`.
`static <T,K,A,D> DistributedCollector<T,?,Map<K,D>>`	`groupingBy(DistributedFunction<? super T,? extends K> classifier, DistributedCollector<? super T,A,D> downstream)` Returns a `DistributedCollector` implementing a cascaded "group by" operation on input elements of type `T`, grouping elements according to a classification function, and then performing a reduction operation on the values associated with a given key using the specified downstream `DistributedCollector`.
`static <T,K,D,A,M extends Map<K,D>> DistributedCollector<T,?,M>`	`groupingBy(DistributedFunction<? super T,? extends K> classifier, DistributedSupplier<M> mapFactory, DistributedCollector<? super T,A,D> downstream)` Returns a `DistributedCollector` implementing a cascaded "group by" operation on input elements of type `T`, grouping elements according to a classification function, and then performing a reduction operation on the values associated with a given key using the specified downstream `DistributedCollector`.
`static <T,K> DistributedCollector.Reducer<T,com.hazelcast.cache.ICache<K,List<T>>>`	`groupingByToICache(String cacheName, DistributedFunction<? super T,? extends K> classifier)` Returns a `Reducer` implementing a "group by" operation on input elements of type `T`, grouping elements according to a classification function, and returning the results in a new distributed Hazelcast `ICache`.
`static <T,K,A,D> DistributedCollector.Reducer<T,com.hazelcast.cache.ICache<K,D>>`	`groupingByToICache(String cacheName, DistributedFunction<? super T,? extends K> classifier, DistributedCollector<? super T,A,D> downstream)` Returns a `Reducer` implementing a cascaded "group by" operation on input elements of type `T`, grouping elements according to a classification function, and then performing a reduction operation on the values associated with a given key using the specified downstream `DistributedCollector`.
`static <T,K> DistributedCollector.Reducer<T,com.hazelcast.core.IMap<K,List<T>>>`	`groupingByToIMap(String mapName, DistributedFunction<? super T,? extends K> classifier)` Returns a `Reducer` implementing a "group by" operation on input elements of type `T`, grouping elements according to a classification function, and returning the results in a new distributed Hazelcast `IMap`.
`static <T,K,A,D> DistributedCollector.Reducer<T,com.hazelcast.core.IMap<K,D>>`	`groupingByToIMap(String mapName, DistributedFunction<? super T,? extends K> classifier, DistributedCollector<? super T,A,D> downstream)` Returns a `Reducer` implementing a cascaded "group by" operation on input elements of type `T`, grouping elements according to a classification function, and then performing a reduction operation on the values associated with a given key using the specified downstream `DistributedCollector`.
`static DistributedCollector<CharSequence,?,String>`	`joining()` Returns a `DistributedCollector` that concatenates the input elements into a `String`, in encounter order.
`static DistributedCollector<CharSequence,?,String>`	`joining(CharSequence delimiter)` Returns a `DistributedCollector` that concatenates the input elements, separated by the specified delimiter, in encounter order.
`static DistributedCollector<CharSequence,?,String>`	`joining(CharSequence delimiter, CharSequence prefix, CharSequence suffix)` Returns a `DistributedCollector` that concatenates the input elements, separated by the specified delimiter, with the specified prefix and suffix, in encounter order.
`static <T,U,A,R> DistributedCollector<T,?,R>`	`mapping(DistributedFunction<? super T,? extends U> mapper, DistributedCollector<? super U,A,R> downstream)` Adapts a `DistributedCollector` accepting elements of type `U` to one accepting elements of type `T` by applying a mapping function to each input element before accumulation.
`static <T> DistributedCollector<T,?,DistributedOptional<T>>`	`maxBy(DistributedComparator<? super T> comparator)` Returns a `DistributedCollector` that produces the maximal element according to a given `DistributedComparator`, described as an `Optional<T>`.
`static <T> DistributedCollector<T,?,DistributedOptional<T>>`	`minBy(DistributedComparator<? super T> comparator)` Returns a `DistributedCollector` that produces the minimal element according to a given `DistributedComparator`, described as an `Optional<T>`.
`static <T> java.util.stream.Collector<T,?,Map<Boolean,List<T>>>`	`partitioningBy(DistributedPredicate<? super T> predicate)` Returns a `DistributedCollector` which partitions the input elements according to a `DistributedPredicate`, and organizes them into a `Map<Boolean, List<T>>`.
`static <T,D,A> java.util.stream.Collector<T,?,Map<Boolean,D>>`	`partitioningBy(DistributedPredicate<? super T> predicate, DistributedCollector<? super T,A,D> downstream)` Returns a `DistributedCollector` which partitions the input elements according to a `DistributedPredicate`, reduces the values in each partition according to another `DistributedCollector`, and organizes them into a `Map<Boolean, D>` whose values are the result of the downstream reduction.
`static <T> DistributedCollector<T,?,DistributedOptional<T>>`	`reducing(DistributedBinaryOperator<T> op)` Returns a `DistributedCollector` which performs a reduction of its input elements under a specified `DistributedBinaryOperator`.
`static <T> DistributedCollector<T,?,T>`	`reducing(T identity, DistributedBinaryOperator<T> op)` Returns a `DistributedCollector` which performs a reduction of its input elements under a specified `DistributedBinaryOperator` using the provided identity.
`static <T,U> DistributedCollector<T,?,U>`	`reducing(U identity, DistributedFunction<? super T,? extends U> mapper, DistributedBinaryOperator<U> op)` Returns a `DistributedCollector` which performs a reduction of its input elements under a specified mapping function and `DistributedBinaryOperator`.
`static <T> DistributedCollector<T,?,DoubleSummaryStatistics>`	`summarizingDouble(DistributedToDoubleFunction<? super T> mapper)` Returns a `DistributedCollector` which applies an `double`-producing mapping function to each input element, and returns summary statistics for the resulting values.
`static <T> DistributedCollector<T,?,IntSummaryStatistics>`	`summarizingInt(DistributedToIntFunction<? super T> mapper)` Returns a `DistributedCollector` which applies an `int`-producing mapping function to each input element, and returns summary statistics for the resulting values.
`static <T> DistributedCollector<T,?,LongSummaryStatistics>`	`summarizingLong(DistributedToLongFunction<? super T> mapper)` Returns a `DistributedCollector` which applies an `long`-producing mapping function to each input element, and returns summary statistics for the resulting values.
`static <T> DistributedCollector<T,?,Double>`	`summingDouble(DistributedToDoubleFunction<? super T> mapper)` Returns a `DistributedCollector` that produces the sum of a double-valued function applied to the input elements.
`static <T> DistributedCollector<T,?,Integer>`	`summingInt(DistributedToIntFunction<? super T> mapper)` Returns a `DistributedCollector` that produces the sum of a integer-valued function applied to the input elements.
`static <T> DistributedCollector<T,?,Long>`	`summingLong(DistributedToLongFunction<? super T> mapper)` Returns a `DistributedCollector` that produces the sum of a long-valued function applied to the input elements.
`static <T,C extends Collection<T>> DistributedCollector<T,?,C>`	`toCollection(DistributedSupplier<C> collectionFactory)` Returns a `DistributedCollector` that accumulates the input elements into a new `Collection`, in encounter order.
`static <K,U> DistributedCollector.Reducer<Map.Entry<K,U>,IStreamCache<K,U>>`	`toICache(String cacheName)` Returns a `Reducer` that accumulates elements into a new distributed Hazelcast `ICache` whose keys and values are the keys and values of the corresponding `Cache.Entry`.
`static <T,K,U> DistributedCollector.Reducer<T,IStreamCache<K,U>>`	`toICache(String cacheName, DistributedFunction<? super T,? extends K> keyMapper, DistributedFunction<? super T,? extends U> valueMapper)` Returns a `Reducer` that accumulates elements into a new Hazelcast `ICache` whose keys and values are the result of applying the provided mapping functions to the input elements.
`static <T,K,U> DistributedCollector.Reducer<T,IStreamCache<K,U>>`	`toICache(String cacheName, DistributedFunction<? super T,? extends K> keyMapper, DistributedFunction<? super T,? extends U> valueMapper, DistributedBinaryOperator<U> mergeFunction)` Returns a `Reducer` that accumulates elements into a new distributed Hazelcast `ICache` whose keys and values are the result of applying the provided mapping functions to the input elements.
`static <T> DistributedCollector.Reducer<T,IStreamList<T>>`	`toIList(String listName)` Returns a `Reducer` that accumulates the input elements into a new Hazelcast `IList`.
`static <K,U> DistributedCollector.Reducer<Map.Entry<K,U>,IStreamMap<K,U>>`	`toIMap(String mapName)` Returns a `Reducer` that accumulates elements into a new distributed Hazelcast `IMap` whose keys and values are the keys and values of the corresponding `Map.Entry`.
`static <T,K,U> DistributedCollector.Reducer<T,IStreamMap<K,U>>`	`toIMap(String mapName, DistributedFunction<? super T,? extends K> keyMapper, DistributedFunction<? super T,? extends U> valueMapper)` Returns a `Reducer` that accumulates elements into a new Hazelcast `IMap` whose keys and values are the result of applying the provided mapping functions to the input elements.
`static <T,K,U> DistributedCollector.Reducer<T,IStreamMap<K,U>>`	`toIMap(String mapName, DistributedFunction<? super T,? extends K> keyMapper, DistributedFunction<? super T,? extends U> valueMapper, DistributedBinaryOperator<U> mergeFunction)` Returns a `Reducer` that accumulates elements into a new distributed Hazelcast `IMap` whose keys and values are the result of applying the provided mapping functions to the input elements.
`static <T> DistributedCollector<T,?,List<T>>`	`toList()` Returns a `DistributedCollector` that accumulates the input elements into a new `List`.
`static <T,K,U> DistributedCollector<T,?,Map<K,U>>`	`toMap(DistributedFunction<? super T,? extends K> keyMapper, DistributedFunction<? super T,? extends U> valueMapper)` Returns a `DistributedCollector` that accumulates elements into a `Map` whose keys and values are the result of applying the provided mapping functions to the input elements.
`static <T,K,U> java.util.stream.Collector<T,?,Map<K,U>>`	`toMap(DistributedFunction<? super T,? extends K> keyMapper, DistributedFunction<? super T,? extends U> valueMapper, DistributedBinaryOperator<U> mergeFunction)` Returns a `DistributedCollector` that accumulates elements into a `Map` whose keys and values are the result of applying the provided mapping functions to the input elements.
`static <T,K,U,M extends Map<K,U>> DistributedCollector<T,?,M>`	`toMap(DistributedFunction<? super T,? extends K> keyMapper, DistributedFunction<? super T,? extends U> valueMapper, DistributedBinaryOperator<U> mergeFunction, DistributedSupplier<M> mapSupplier)` Returns a `DistributedCollector` that accumulates elements into a `Map` whose keys and values are the result of applying the provided mapping functions to the input elements.
`static <T> DistributedCollector<T,?,Set<T>>`	`toSet()` Returns a `DistributedCollector` that accumulates the input elements into a new `Set`.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
 - DistributedCollectors
```
public DistributedCollectors()
```
- Method Detail
 - toCollection
```
public static <T,C extends Collection<T>> DistributedCollector<T,?,C> toCollection(DistributedSupplier<C> collectionFactory)
```
 Returns a DistributedCollector that accumulates the input elements into a new Collection, in encounter order. The Collection is created by the provided factory.
 
 Type Parameters:
 
 T - the type of the input elements
 
 C - the type of the resulting Collection
 
 Parameters:
 
 collectionFactory - a DistributedSupplier which returns a new, empty Collection of the appropriate type
 
 Returns:
 
 a DistributedCollector which collects all the input elements into a Collection, in encounter order
 - toList
```
public static <T> DistributedCollector<T,?,List<T>> toList()
```
 Returns a DistributedCollector that accumulates the input elements into a new List. There are no guarantees on the type, mutability, serializability, or thread-safety of the List returned; if more control over the returned List is required, use toCollection(DistributedSupplier).
 
 Type Parameters:
 
 T - the type of the input elements
 
 Returns:
 
 a DistributedCollector which collects all the input elements into a List, in encounter order
 - toSet
```
public static <T> DistributedCollector<T,?,Set<T>> toSet()
```
 Returns a DistributedCollector that accumulates the input elements into a new Set. There are no guarantees on the type, mutability, serializability, or thread-safety of the Set returned; if more control over the returned Set is required, use toCollection(DistributedSupplier).
 
 This is an unordered Collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Returns:
 
 a DistributedCollector which collects all the input elements into a Set
 - joining
```
public static DistributedCollector<CharSequence,?,String> joining()
```
 Returns a DistributedCollector that concatenates the input elements into a String, in encounter order.
 
 Returns:
 
 a DistributedCollector that concatenates the input elements into a String, in encounter order
 - joining
```
public static DistributedCollector<CharSequence,?,String> joining(CharSequence delimiter)
```
 Returns a DistributedCollector that concatenates the input elements, separated by the specified delimiter, in encounter order.
 
 Parameters:
 
 delimiter - the delimiter to be used between each element
 
 Returns:
 
 A DistributedCollector which concatenates CharSequence elements, separated by the specified delimiter, in encounter order
 - joining
```
public static DistributedCollector<CharSequence,?,String> joining(CharSequence delimiter,
 CharSequence prefix,
 CharSequence suffix)
```
 Returns a DistributedCollector that concatenates the input elements, separated by the specified delimiter, with the specified prefix and suffix, in encounter order.
 
 Parameters:
 
 delimiter - the delimiter to be used between each element
 
 prefix - the sequence of characters to be used at the beginning of the joined result
 
 suffix - the sequence of characters to be used at the end of the joined result
 
 Returns:
 
 A DistributedCollector which concatenates CharSequence elements, separated by the specified delimiter, in encounter order
 - mapping
```
public static <T,U,A,R> DistributedCollector<T,?,R> mapping(DistributedFunction<? super T,? extends U> mapper,
 DistributedCollector<? super U,A,R> downstream)
```
 Adapts a DistributedCollector accepting elements of type U to one accepting elements of type T by applying a mapping function to each input element before accumulation.
 
 Type Parameters:
 
 T - the type of the input elements
 
 U - type of elements accepted by downstream collector
 
 A - intermediate accumulation type of the downstream collector
 
 R - result type of collector
 
 Parameters:
 
 mapper - a function to be applied to the input elements
 
 downstream - a collector which will accept mapped values
 
 Returns:
 
 a collector which applies the mapping function to the input elements and provides the mapped results to the downstream collector
 - collectingAndThen
```
public static <T,A,R,RR> DistributedCollector<T,A,RR> collectingAndThen(DistributedCollector<T,A,R> downstream,
 DistributedFunction<R,RR> finisher)
```
 Adapts a DistributedCollector to perform an additional finishing transformation. For example, one could adapt the toList() collector to always produce an immutable list with:
```
 List<String> people
 = people.stream().collect(collectingAndThen(toList(), Collections::unmodifiableList));
 
```
 Type Parameters:
 
 T - the type of the input elements
 
 A - intermediate accumulation type of the downstream collector
 
 R - result type of the downstream collector
 
 RR - result type of the resulting collector
 
 Parameters:
 
 downstream - a collector
 
 finisher - a function to be applied to the final result of the downstream collector
 
 Returns:
 
 a collector which performs the action of the downstream collector, followed by an additional finishing step
 - counting
```
public static <T> DistributedCollector<T,?,Long> counting()
```
 Returns a DistributedCollector accepting elements of type T that counts the number of input elements. If no elements are present, the result is 0.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Returns:
 
 a DistributedCollector that counts the input elements
 - minBy
```
public static <T> DistributedCollector<T,?,DistributedOptional<T>> minBy(DistributedComparator<? super T> comparator)
```
 Returns a DistributedCollector that produces the minimal element according to a given DistributedComparator, described as an Optional<T>.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 comparator - a DistributedComparator for comparing elements
 
 Returns:
 
 a DistributedCollector that produces the minimal value
 - maxBy
```
public static <T> DistributedCollector<T,?,DistributedOptional<T>> maxBy(DistributedComparator<? super T> comparator)
```
 Returns a DistributedCollector that produces the maximal element according to a given DistributedComparator, described as an Optional<T>.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 comparator - a DistributedComparator for comparing elements
 
 Returns:
 
 a DistributedCollector that produces the maximal value
 - summingInt
```
public static <T> DistributedCollector<T,?,Integer> summingInt(DistributedToIntFunction<? super T> mapper)
```
 Returns a DistributedCollector that produces the sum of a integer-valued function applied to the input elements. If no elements are present, the result is 0.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - a function extracting the property to be summed
 
 Returns:
 
 a DistributedCollector that produces the sum of a derived property
 - summingLong
```
public static <T> DistributedCollector<T,?,Long> summingLong(DistributedToLongFunction<? super T> mapper)
```
 Returns a DistributedCollector that produces the sum of a long-valued function applied to the input elements. If no elements are present, the result is 0.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - a function extracting the property to be summed
 
 Returns:
 
 a DistributedCollector that produces the sum of a derived property
 - summingDouble
```
public static <T> DistributedCollector<T,?,Double> summingDouble(DistributedToDoubleFunction<? super T> mapper)
```
 Returns a DistributedCollector that produces the sum of a double-valued function applied to the input elements. If no elements are present, the result is 0.
 
 The sum returned can vary depending upon the order in which values are recorded, due to accumulated rounding error in addition of values of differing magnitudes. Values sorted by increasing absolute magnitude tend to yield more accurate results. If any recorded value is a NaN or the sum is at any point a NaN then the sum will be NaN.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - a function extracting the property to be summed
 
 Returns:
 
 a DistributedCollector that produces the sum of a derived property
 - averagingInt
```
public static <T> DistributedCollector<T,?,Double> averagingInt(DistributedToIntFunction<? super T> mapper)
```
 Returns a DistributedCollector that produces the arithmetic mean of an integer-valued function applied to the input elements. If no elements are present, the result is 0.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - a function extracting the property to be summed
 
 Returns:
 
 a DistributedCollector that produces the sum of a derived property
 - averagingLong
```
public static <T> DistributedCollector<T,?,Double> averagingLong(DistributedToLongFunction<? super T> mapper)
```
 Returns a DistributedCollector that produces the arithmetic mean of a long-valued function applied to the input elements. If no elements are present, the result is 0.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - a function extracting the property to be summed
 
 Returns:
 
 a DistributedCollector that produces the sum of a derived property
 - averagingDouble
```
public static <T> DistributedCollector<T,?,Double> averagingDouble(DistributedToDoubleFunction<? super T> mapper)
```
 Returns a DistributedCollector that produces the arithmetic mean of a double-valued function applied to the input elements. If no elements are present, the result is 0.
 
 The average returned can vary depending upon the order in which values are recorded, due to accumulated rounding error in addition of values of differing magnitudes. Values sorted by increasing absolute magnitude tend to yield more accurate results. If any recorded value is a NaN or the sum is at any point a NaN then the average will be NaN.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - a function extracting the property to be summed
 
 Returns:
 
 a DistributedCollector that produces the sum of a derived property
 - reducing
```
public static <T> DistributedCollector<T,?,T> reducing(T identity,
 DistributedBinaryOperator<T> op)
```
 Returns a DistributedCollector which performs a reduction of its input elements under a specified DistributedBinaryOperator using the provided identity.
 
 Type Parameters:
 
 T - element type for the input and output of the reduction
 
 Parameters:
 
 identity - the identity value for the reduction (also, the value that is returned when there are no input elements)
 
 op - a DistributedBinaryOperator<T> used to reduce the input elements
 
 Returns:
 
 a DistributedCollector which implements the reduction operation
 
 See Also:
 
 reducing(DistributedBinaryOperator), reducing(Object, DistributedFunction, DistributedBinaryOperator)
 - reducing
```
public static <T> DistributedCollector<T,?,DistributedOptional<T>> reducing(DistributedBinaryOperator<T> op)
```
 Returns a DistributedCollector which performs a reduction of its input elements under a specified DistributedBinaryOperator. The result is described as an Optional<T>.
 
 Type Parameters:
 
 T - element type for the input and output of the reduction
 
 Parameters:
 
 op - a DistributedBinaryOperator<T> used to reduce the input elements
 
 Returns:
 
 a DistributedCollector which implements the reduction operation
 
 See Also:
 
 reducing(Object, DistributedBinaryOperator), reducing(Object, DistributedFunction, DistributedBinaryOperator)
 - reducing
```
public static <T,U> DistributedCollector<T,?,U> reducing(U identity,
 DistributedFunction<? super T,? extends U> mapper,
 DistributedBinaryOperator op)
```
 Returns a DistributedCollector which performs a reduction of its input elements under a specified mapping function and DistributedBinaryOperator. This is a generalization of reducing(Object, DistributedBinaryOperator) which allows a transformation of the elements before reduction.
 
 Type Parameters:
 
 T - the type of the input elements
 
 U - the type of the mapped values
 
 Parameters:
 
 identity - the identity value for the reduction (also, the value that is returned when there are no input elements)
 
 mapper - a mapping function to apply to each input value
 
 op - a DistributedBinaryOperator used to reduce the mapped values
 
 Returns:
 
 a DistributedCollector implementing the map-reduce operation
 
 See Also:
 
 reducing(Object, DistributedBinaryOperator), reducing(DistributedBinaryOperator)
 - groupingBy
```
public static <T,K> DistributedCollector<T,?,Map<K,List<T>>> groupingBy(DistributedFunction<? super T,? extends K> classifier)
```
 Returns a DistributedCollector implementing a "group by" operation on input elements of type T, grouping elements according to a classification function, and returning the results in a Map.
 
 The classification function maps elements to some key type K. The collector produces a Map<K, List<T>> whose keys are the values resulting from applying the classification function to the input elements, and whose corresponding values are Lists containing the input elements which map to the associated key under the classification function.
 
 There are no guarantees on the type, mutability, serializability, or thread-safety of the Map or List objects returned.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the type of the keys
 
 Parameters:
 
 classifier - the classifier function mapping input elements to keys
 
 Returns:
 
 a DistributedCollector implementing the group-by operation
 
 See Also:
 
 groupingBy(DistributedFunction, DistributedCollector), groupingBy(DistributedFunction, DistributedSupplier, DistributedCollector)
 - groupingBy
```
public static <T,K,A,D> DistributedCollector<T,?,Map<K,D>> groupingBy(DistributedFunction<? super T,? extends K> classifier,
 DistributedCollector<? super T,A,D> downstream)
```
 Returns a DistributedCollector implementing a cascaded "group by" operation on input elements of type T, grouping elements according to a classification function, and then performing a reduction operation on the values associated with a given key using the specified downstream DistributedCollector.
 
 The classification function maps elements to some key type K. The downstream collector operates on elements of type T and produces a result of type D. The resulting collector produces a Map<K, D>.
 
 There are no guarantees on the type, mutability, serializability, or thread-safety of the Map returned.
 
 For example, to compute the set of last names of people in each city:
```
 Map<City, Set<String>> namesByCity
 = people.stream().collect(groupingBy(Person::getCity,
 mapping(Person::getLastName, toSet())));
 
```
 Type Parameters:
 
 T - the type of the input elements
 
 K - the type of the keys
 
 A - the intermediate accumulation type of the downstream collector
 
 D - the result type of the downstream reduction
 
 Parameters:
 
 classifier - a classifier function mapping input elements to keys
 
 downstream - a DistributedCollector implementing the downstream reduction
 
 Returns:
 
 a DistributedCollector implementing the cascaded group-by operation
 
 See Also:
 
 groupingBy(DistributedFunction), groupingBy(DistributedFunction, DistributedSupplier, DistributedCollector)
 - groupingBy
```
public static <T,K,D,A,M extends Map<K,D>> DistributedCollector<T,?,M> groupingBy(DistributedFunction<? super T,? extends K> classifier,
 DistributedSupplier<M> mapFactory,
 DistributedCollector<? super T,A,D> downstream)
```
 Returns a DistributedCollector implementing a cascaded "group by" operation on input elements of type T, grouping elements according to a classification function, and then performing a reduction operation on the values associated with a given key using the specified downstream DistributedCollector. The Map produced by the Collector is created with the supplied factory function.
 
 The classification function maps elements to some key type K. The downstream collector operates on elements of type T and produces a result of type D. The resulting collector produces a Map<K, D>.
 
 For example, to compute the set of last names of people in each city, where the city names are sorted:
```
 Map<City, Set<String>> namesByCity
 = people.stream().collect(groupingBy(Person::getCity, TreeMap::new,
 mapping(Person::getLastName, toSet())));
 
```
 Type Parameters:
 
 T - the type of the input elements
 
 K - the type of the keys
 
 A - the intermediate accumulation type of the downstream collector
 
 D - the result type of the downstream reduction
 
 M - the type of the resulting Map
 
 Parameters:
 
 classifier - a classifier function mapping input elements to keys
 
 downstream - a DistributedCollector implementing the downstream reduction
 
 mapFactory - a function which, when called, produces a new empty Map of the desired type
 
 Returns:
 
 a DistributedCollector implementing the cascaded group-by operation
 
 See Also:
 
 groupingBy(DistributedFunction, DistributedCollector), groupingBy(DistributedFunction)
 - partitioningBy
```
public static <T> java.util.stream.Collector<T,?,Map<Boolean,List<T>>> partitioningBy(DistributedPredicate<? super T> predicate)
```
 Returns a DistributedCollector which partitions the input elements according to a DistributedPredicate, and organizes them into a Map<Boolean, List<T>>.
 There are no guarantees on the type, mutability, serializability, or thread-safety of the Map returned.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 predicate - a predicate used for classifying input elements
 
 Returns:
 
 a DistributedCollector implementing the partitioning operation
 
 See Also:
 
 partitioningBy(DistributedPredicate, DistributedCollector)
 - partitioningBy
```
public static <T,D,A> java.util.stream.Collector<T,?,Map<Boolean,D>> partitioningBy(DistributedPredicate<? super T> predicate,
 DistributedCollector<? super T,A,D> downstream)
```
 Returns a DistributedCollector which partitions the input elements according to a DistributedPredicate, reduces the values in each partition according to another DistributedCollector, and organizes them into a Map<Boolean, D> whose values are the result of the downstream reduction.
 
 There are no guarantees on the type, mutability, serializability, or thread-safety of the Map returned.
 
 Type Parameters:
 
 T - the type of the input elements
 
 A - the intermediate accumulation type of the downstream collector
 
 D - the result type of the downstream reduction
 
 Parameters:
 
 predicate - a predicate used for classifying input elements
 
 downstream - a DistributedCollector implementing the downstream reduction
 
 Returns:
 
 a DistributedCollector implementing the cascaded partitioning operation
 
 See Also:
 
 partitioningBy(DistributedPredicate)
 - toMap
```
public static <T,K,U> DistributedCollector<T,?,Map<K,U>> toMap(DistributedFunction<? super T,? extends K> keyMapper,
 DistributedFunction<? super T,? extends U> valueMapper)
```
 Returns a DistributedCollector that accumulates elements into a Map whose keys and values are the result of applying the provided mapping functions to the input elements.
 
 If the mapped keys contains duplicates (according to Object.equals(Object)), an IllegalStateException is thrown when the collection operation is performed. If the mapped keys may have duplicates, use toMap(DistributedFunction, DistributedFunction, DistributedBinaryOperator) instead.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the output type of the key mapping function
 
 U - the output type of the value mapping function
 
 Parameters:
 
 keyMapper - a mapping function to produce keys
 
 valueMapper - a mapping function to produce values
 
 Returns:
 
 a DistributedCollector which collects elements into a Map whose keys and values are the result of applying mapping functions to the input elements
 
 See Also:
 
 toMap(DistributedFunction, DistributedFunction, DistributedBinaryOperator), toMap(DistributedFunction, DistributedFunction, DistributedBinaryOperator, DistributedSupplier)
 - toMap
```
public static <T,K,U> java.util.stream.Collector<T,?,Map<K,U>> toMap(DistributedFunction<? super T,? extends K> keyMapper,
 DistributedFunction<? super T,? extends U> valueMapper,
 DistributedBinaryOperator mergeFunction)
```
 Returns a DistributedCollector that accumulates elements into a Map whose keys and values are the result of applying the provided mapping functions to the input elements.
 
 If the mapped keys contains duplicates (according to Object.equals(Object)), the value mapping function is applied to each equal element, and the results are merged using the provided merging function.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the output type of the key mapping function
 
 U - the output type of the value mapping function
 
 Parameters:
 
 keyMapper - a mapping function to produce keys
 
 valueMapper - a mapping function to produce values
 
 mergeFunction - a merge function, used to resolve collisions between values associated with the same key, as supplied to Map.merge(Object, Object, java.util.function.BiFunction)
 
 Returns:
 
 a DistributedCollector which collects elements into a Map whose keys are the result of applying a key mapping function to the input elements, and whose values are the result of applying a value mapping function to all input elements equal to the key and combining them using the merge function
 
 See Also:
 
 toMap(DistributedFunction, DistributedFunction), toMap(DistributedFunction, DistributedFunction, DistributedBinaryOperator, DistributedSupplier)
 - toMap
```
public static <T,K,U,M extends Map<K,U>> DistributedCollector<T,?,M> toMap(DistributedFunction<? super T,? extends K> keyMapper,
 DistributedFunction<? super T,? extends U> valueMapper,
 DistributedBinaryOperator mergeFunction,
 DistributedSupplier<M> mapSupplier)
```
 Returns a DistributedCollector that accumulates elements into a Map whose keys and values are the result of applying the provided mapping functions to the input elements.
 
 If the mapped keys contains duplicates (according to Object.equals(Object)), the value mapping function is applied to each equal element, and the results are merged using the provided merging function. The Map is created by a provided supplier function.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the output type of the key mapping function
 
 U - the output type of the value mapping function
 
 M - the type of the resulting Map
 
 Parameters:
 
 keyMapper - a mapping function to produce keys
 
 valueMapper - a mapping function to produce values
 
 mergeFunction - a merge function, used to resolve collisions between values associated with the same key, as supplied to Map.merge(Object, Object, java.util.function.BiFunction)
 
 mapSupplier - a function which returns a new, empty Map into which the results will be inserted
 
 Returns:
 
 a DistributedCollector which collects elements into a Map whose keys are the result of applying a key mapping function to the input elements, and whose values are the result of applying a value mapping function to all input elements equal to the key and combining them using the merge function
 
 See Also:
 
 toMap(DistributedFunction, DistributedFunction), toMap(DistributedFunction, DistributedFunction, DistributedBinaryOperator)
 - summarizingInt
```
public static <T> DistributedCollector<T,?,IntSummaryStatistics> summarizingInt(DistributedToIntFunction<? super T> mapper)
```
 Returns a DistributedCollector which applies an int-producing mapping function to each input element, and returns summary statistics for the resulting values.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - a mapping function to apply to each element
 
 Returns:
 
 a DistributedCollector implementing the summary-statistics reduction
 
 See Also:
 
 summarizingDouble(DistributedToDoubleFunction), summarizingLong(DistributedToLongFunction)
 - summarizingLong
```
public static <T> DistributedCollector<T,?,LongSummaryStatistics> summarizingLong(DistributedToLongFunction<? super T> mapper)
```
 Returns a DistributedCollector which applies an long-producing mapping function to each input element, and returns summary statistics for the resulting values.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - the mapping function to apply to each element
 
 Returns:
 
 a DistributedCollector implementing the summary-statistics reduction
 
 See Also:
 
 summarizingDouble(DistributedToDoubleFunction), summarizingInt(DistributedToIntFunction)
 - summarizingDouble
```
public static <T> DistributedCollector<T,?,DoubleSummaryStatistics> summarizingDouble(DistributedToDoubleFunction<? super T> mapper)
```
 Returns a DistributedCollector which applies an double-producing mapping function to each input element, and returns summary statistics for the resulting values.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - a mapping function to apply to each element
 
 Returns:
 
 a DistributedCollector implementing the summary-statistics reduction
 
 See Also:
 
 summarizingLong(DistributedToLongFunction), summarizingInt(DistributedToIntFunction)
 - toIMap
```
public static <T,K,U> DistributedCollector.Reducer<T,IStreamMap<K,U>> toIMap(String mapName,
 DistributedFunction<? super T,? extends K> keyMapper,
 DistributedFunction<? super T,? extends U> valueMapper)
```
 Returns a Reducer that accumulates elements into a new Hazelcast IMap whose keys and values are the result of applying the provided mapping functions to the input elements.
 
 If the mapped keys contains duplicates (according to Object.equals(Object)), only one of the mapped values will be in the final map, and the others will be dropped. If the mapped keys may have duplicates, use toMap(DistributedFunction, DistributedFunction, DistributedBinaryOperator) instead.
 The returned collector may not be used as a downstream collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the output type of the key mapping function
 
 U - the output type of the value mapping function
 
 Parameters:
 
 mapName - Name of the map to store the results
 
 keyMapper - a mapping function to produce keys
 
 valueMapper - a mapping function to produce values
 
 Returns:
 
 a Reducer which collects elements into a IMap whose keys and values are the result of applying mapping functions to the input elements
 
 See Also:
 
 toIMap(String, DistributedFunction, DistributedFunction, DistributedBinaryOperator)
 - toIMap
```
public static <K,U> DistributedCollector.Reducer<Map.Entry<K,U>,IStreamMap<K,U>> toIMap(String mapName)
```
 Returns a Reducer that accumulates elements into a new distributed Hazelcast IMap whose keys and values are the keys and values of the corresponding Map.Entry.
 *
 If the mapped keys contains duplicates (according to Object.equals(Object)), only one of the mapped values will be in the final map, and the others will be dropped. If the mapped keys may have duplicates, use toMap(DistributedFunction, DistributedFunction, DistributedBinaryOperator) instead.
 The returned collector may not be used as a downstream collector.
 
 Type Parameters:
 
 K - The type of the key in Map.Entry
 
 U - The type of the value in Map.Entry
 
 Parameters:
 
 mapName - Name of the map to store the results
 
 Returns:
 
 a Reducer that accumulates elements into a Hazelcast IMap whose keys and values are the keys and values of the corresponding Map.Entry.
 
 See Also:
 
 toIMap(String, DistributedFunction, DistributedFunction), toIMap(String, DistributedFunction, DistributedFunction, DistributedBinaryOperator)
 - toIMap
```
public static <T,K,U> DistributedCollector.Reducer<T,IStreamMap<K,U>> toIMap(String mapName,
 DistributedFunction<? super T,? extends K> keyMapper,
 DistributedFunction<? super T,? extends U> valueMapper,
 DistributedBinaryOperator mergeFunction)
```
 Returns a Reducer that accumulates elements into a new distributed Hazelcast IMap whose keys and values are the result of applying the provided mapping functions to the input elements.
 
 If the mapped keys contains duplicates (according to Object.equals(Object)), the value mapping function is applied to each equal element, and the results are merged using the provided merging function.
 The returned collector may not be used as a downstream collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the output type of the key mapping function
 
 U - the output type of the value mapping function
 
 Parameters:
 
 mapName - Name of the map to store the results
 
 keyMapper - a mapping function to produce keys
 
 valueMapper - a mapping function to produce values
 
 mergeFunction - a merge function, used to resolve collisions between values associated with the same key, as supplied to Map.merge(Object, Object, java.util.function.BiFunction)
 
 Returns:
 
 a Reducer which collects elements into a distributed IMap whose keys are the result of applying a key mapping function to the input elements, and whose values are the result of applying a value mapping function to all input elements equal to the key and combining them using the merge function
 
 See Also:
 
 toIMap(String, DistributedFunction, DistributedFunction)
 - toICache
```
public static <T,K,U> DistributedCollector.Reducer<T,IStreamCache<K,U>> toICache(String cacheName,
 DistributedFunction<? super T,? extends K> keyMapper,
 DistributedFunction<? super T,? extends U> valueMapper)
```
 Returns a Reducer that accumulates elements into a new Hazelcast ICache whose keys and values are the result of applying the provided mapping functions to the input elements.
 
 If the mapped keys contains duplicates (according to Object.equals(Object)), only one of the mapped values will be in the final map, and the others will be dropped. If the mapped keys may have duplicates, use toMap(DistributedFunction, DistributedFunction, DistributedBinaryOperator) instead.
 The returned collector may not be used as a downstream collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the output type of the key mapping function
 
 U - the output type of the value mapping function
 
 Parameters:
 
 cacheName - Name of the cache to store the results
 
 keyMapper - a mapping function to produce keys
 
 valueMapper - a mapping function to produce values
 
 Returns:
 
 a Reducer which collects elements into a ICache whose keys and values are the result of applying mapping functions to the input elements
 
 See Also:
 
 toICache(String, DistributedFunction, DistributedFunction, DistributedBinaryOperator)
 - toICache
```
public static <K,U> DistributedCollector.Reducer<Map.Entry<K,U>,IStreamCache<K,U>> toICache(String cacheName)
```
 Returns a Reducer that accumulates elements into a new distributed Hazelcast ICache whose keys and values are the keys and values of the corresponding Cache.Entry.
 *
 If the mapped keys contains duplicates (according to Object.equals(Object)), only one of the mapped values will be in the final map, and the others will be dropped. If the mapped keys may have duplicates, use toMap(DistributedFunction, DistributedFunction, DistributedBinaryOperator) instead.
 The returned collector may not be used as a downstream collector.
 
 Type Parameters:
 
 K - The type of the key in Cache.Entry
 
 U - The type of the value in Cache.Entry
 
 Parameters:
 
 cacheName - Name of the cache to store the results
 
 Returns:
 
 a Reducer that accumulates elements into a Hazelcast ICache whose keys and values are the keys and values of the corresponding Cache.Entry.
 
 See Also:
 
 toICache(String, DistributedFunction, DistributedFunction), toICache(String, DistributedFunction, DistributedFunction, DistributedBinaryOperator)
 - toICache
```
public static <T,K,U> DistributedCollector.Reducer<T,IStreamCache<K,U>> toICache(String cacheName,
 DistributedFunction<? super T,? extends K> keyMapper,
 DistributedFunction<? super T,? extends U> valueMapper,
 DistributedBinaryOperator mergeFunction)
```
 Returns a Reducer that accumulates elements into a new distributed Hazelcast ICache whose keys and values are the result of applying the provided mapping functions to the input elements.
 
 If the mapped keys contains duplicates (according to Object.equals(Object)), the value mapping function is applied to each equal element, and the results are merged using the provided merging function.
 The returned collector may not be used as a downstream collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the output type of the key mapping function
 
 U - the output type of the value mapping function
 
 Parameters:
 
 cacheName - Name of the cache to store the results
 
 keyMapper - a mapping function to produce keys
 
 valueMapper - a mapping function to produce values
 
 mergeFunction - a merge function, used to resolve collisions between values associated with the same key, as supplied to Map.merge(Object, Object, java.util.function.BiFunction)
 
 Returns:
 
 a Reducer which collects elements into a distributed ICache whose keys are the result of applying a key mapping function to the input elements, and whose values are the result of applying a value mapping function to all input elements equal to the key and combining them using the merge function
 
 See Also:
 
 toICache(String, DistributedFunction, DistributedFunction)
 - toIList
```
public static <T> DistributedCollector.Reducer<T,IStreamList<T>> toIList(String listName)
```
 Returns a Reducer that accumulates the input elements into a new Hazelcast IList.
 The returned collector may not be used as a downstream collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 listName - Name of the list to store the results
 
 Returns:
 
 a DistributedCollector which collects all the input elements into a Hazelcast IList, in encounter order
 - groupingByToIMap
```
public static <T,K> DistributedCollector.Reducer<T,com.hazelcast.core.IMap<K,List<T>>> groupingByToIMap(String mapName,
 DistributedFunction<? super T,? extends K> classifier)
```
 Returns a Reducer implementing a "group by" operation on input elements of type T, grouping elements according to a classification function, and returning the results in a new distributed Hazelcast IMap.
 
 The classification function maps elements to some key type K. The collector produces a Map<K, List<T>> whose keys are the values resulting from applying the classification function to the input elements, and whose corresponding values are Lists containing the input elements which map to the associated key under the classification function.
 The returned collector may not be used as a downstream collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the type of the keys
 
 Parameters:
 
 mapName - Name of the map to store the results
 
 classifier - the classifier function mapping input elements to keys
 
 Returns:
 
 a Reducer implementing the group-by operation
 
 See Also:
 
 groupingByToIMap(String, DistributedFunction, DistributedCollector)
 - groupingByToIMap
```
public static <T,K,A,D> DistributedCollector.Reducer<T,com.hazelcast.core.IMap<K,D>> groupingByToIMap(String mapName,
 DistributedFunction<? super T,? extends K> classifier,
 DistributedCollector<? super T,A,D> downstream)
```
 Returns a Reducer implementing a cascaded "group by" operation on input elements of type T, grouping elements according to a classification function, and then performing a reduction operation on the values associated with a given key using the specified downstream DistributedCollector.
 
 The classification function maps elements to some key type K. The downstream collector operates on elements of type T and produces a result of type D. The resulting collector produces a new Hazelcast distributed IMap<K, D>.
 
 For example, to compute the set of last names of people in each city:
```
 IMap<City, Set<String>> namesByCity
 = people.stream().collect(groupingBy(Person::getCity,
 mapping(Person::getLastName, toSet())));
 
```
 Type Parameters:
 
 T - the type of the input elements
 
 K - the type of the keys
 
 A - the intermediate accumulation type of the downstream collector
 
 D - the result type of the downstream reduction
 
 Parameters:
 
 mapName - Name of the map to store the results
 
 classifier - a classifier function mapping input elements to keys
 
 downstream - a DistributedCollector implementing the downstream reduction
 
 Returns:
 
 a Reducer implementing the cascaded group-by operation
 
 See Also:
 
 groupingByToIMap(String, DistributedFunction)
 - groupingByToICache
```
public static <T,K> DistributedCollector.Reducer<T,com.hazelcast.cache.ICache<K,List<T>>> groupingByToICache(String cacheName,
 DistributedFunction<? super T,? extends K> classifier)
```
 Returns a Reducer implementing a "group by" operation on input elements of type T, grouping elements according to a classification function, and returning the results in a new distributed Hazelcast ICache.
 
 The classification function maps elements to some key type K. The collector produces a Map<K, List<T>> whose keys are the values resulting from applying the classification function to the input elements, and whose corresponding values are Lists containing the input elements which map to the associated key under the classification function.
 The returned collector may not be used as a downstream collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the type of the keys
 
 Parameters:
 
 cacheName - Name of the cache to store the results
 
 classifier - the classifier function mapping input elements to keys
 
 Returns:
 
 a Reducer implementing the group-by operation
 
 See Also:
 
 groupingByToICache(String, DistributedFunction, DistributedCollector)
 - groupingByToICache
```
public static <T,K,A,D> DistributedCollector.Reducer<T,com.hazelcast.cache.ICache<K,D>> groupingByToICache(String cacheName,
 DistributedFunction<? super T,? extends K> classifier,
 DistributedCollector<? super T,A,D> downstream)
```
 Returns a Reducer implementing a cascaded "group by" operation on input elements of type T, grouping elements according to a classification function, and then performing a reduction operation on the values associated with a given key using the specified downstream DistributedCollector.
 
 The classification function maps elements to some key type K. The downstream collector operates on elements of type T and produces a result of type D. The resulting collector produces a new Hazelcast distributed ICache<K, D>.
 
 For example, to compute the set of last names of people in each city:
```
 ICache<City, Set<String>> namesByCity
 = people.stream().collect(groupingBy(Person::getCity,
 mapping(Person::getLastName, toSet())));
 
```
 Type Parameters:
 
 T - the type of the input elements
 
 K - the type of the keys
 
 A - the intermediate accumulation type of the downstream collector
 
 D - the result type of the downstream reduction
 
 Parameters:
 
 cacheName - Name of the cache to store the results
 
 classifier - a classifier function mapping input elements to keys
 
 downstream - a DistributedCollector implementing the downstream reduction
 
 Returns:
 
 a Reducer implementing the cascaded group-by operation
 
 See Also:
 
 groupingByToICache(String, DistributedFunction)

Class DistributedCollectors

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

DistributedCollectors

Method Detail

toCollection

toList

toSet

joining

joining

joining

mapping

collectingAndThen

counting

minBy

maxBy

summingInt

summingLong

summingDouble

averagingInt

averagingLong

averagingDouble

reducing

reducing

reducing

groupingBy

groupingBy

groupingBy

partitioningBy

partitioningBy

toMap

toMap

toMap

summarizingInt

summarizingLong

summarizingDouble

toIMap

toIMap

toIMap

toICache

toICache

toICache

toIList

groupingByToIMap

groupingByToIMap

groupingByToICache

groupingByToICache