Collectors (abacus API Documentation)

java.lang.Object
- com.landawn.abacus.util.stream.Collectors

Direct Known Subclasses:: Collectors.MoreCollectors

public class Collectors
extends java.lang.Object

Note: It's copied from OpenJDK at: http://hg.openjdk.java.net/jdk8u/hs-dev/jdk
Implementations of Collector that implement various useful reduction operations, such as accumulating elements into collections, summarizing elements according to various criteria, etc.

The following are examples of using the predefined collectors to perform common mutable reduction tasks:


     // Accumulate names into a List
     List<String> list = people.stream().map(Person::getName).collect(Collectors.toList());

     // Accumulate names into a TreeSet
     Set<String> set = people.stream().map(Person::getName).collect(Collectors.toCollection(TreeSet::new));

     // Convert elements to strings and concatenate them, separated by commas
     String joined = things.stream()
                           .map(Object::toString)
                           .collect(Collectors.joining(", "));

     // Compute sum of salaries of employee
     int total = employees.stream()
                          .collect(Collectors.summingInt(Employee::getSalary)));

     // Group employees by department
     Map<Department, List<Employee>> byDept
         = employees.stream()
                    .collect(Collectors.groupingBy(Employee::getDepartment));

     // Compute sum of salaries by department
     Map<Department, Integer> totalByDept
         = employees.stream()
                    .collect(Collectors.groupingBy(Employee::getDepartment,
                                                   Collectors.summingInt(Employee::getSalary)));

     // Partition students into passing and failing
     Map<Boolean, List<Student>> passingFailing =
         students.stream()
                 .collect(Collectors.partitioningBy(s -> s.getGrade() >= PASS_THRESHOLD));

Since:: 1.8

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class Collectors.MoreCollectors

Nested Classes
Modifier and Type	Class and Description
`static class`	`Collectors.MoreCollectors`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static <T> Collector<T,?,java.lang.Double>`	`averagingDouble(ToDoubleFunction<? super T> mapper)` Returns a `Collector` that produces the arithmetic mean of a double-valued function applied to the input elements.
`static <T> Collector<T,?,OptionalDouble>`	`averagingDouble2(ToDoubleFunction<? super T> mapper)`
`static <T> Collector<T,?,java.lang.Double>`	`averagingInt(ToIntFunction<? super T> mapper)` Returns a `Collector` that produces the arithmetic mean of an integer-valued function applied to the input elements.
`static <T> Collector<T,?,OptionalDouble>`	`averagingInt2(ToIntFunction<? super T> mapper)`
`static <T> Collector<T,?,java.lang.Double>`	`averagingLong(ToLongFunction<? super T> mapper)` Returns a `Collector` that produces the arithmetic mean of a long-valued function applied to the input elements.
`static <T> Collector<T,?,OptionalDouble>`	`averagingLong2(ToLongFunction<? super T> mapper)`
`static <T,A,R,RR> Collector<T,A,RR>`	`collectingAndThen(Collector<T,A,R> downstream, Function<R,RR> finisher)` Adapts a `Collector` to perform an additional finishing transformation.
`static Collector<java.lang.CharSequence,?,java.lang.String>`	`commonPrefix()` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which computes a common prefix of input `CharSequence` objects returning the result as `String`.
`static Collector<java.lang.CharSequence,?,java.lang.String>`	`commonSuffix()` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which computes a common suffix of input `CharSequence` objects returning the result as `String`.
`static <T> Collector<T,?,java.lang.Long>`	`counting()` Returns a `Collector` accepting elements of type `T` that counts the number of input elements.
`static <T> Collector<T,?,java.lang.Integer>`	`countingInt()`
`static <T> Collector<T,?,java.util.List<T>>`	`distinctBy(Function<? super T,?> mapper)` Returns a `Collector` which collects into the `List` the input elements for which given mapper function returns distinct results.
`static <T> Collector<T,?,java.lang.Integer>`	`distinctCount(Function<? super T,?> mapper)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which counts a number of distinct values the mapper function returns for the stream elements.
`static <T> Collector<T,?,java.util.List<T>>`	`dominators(BiPredicate<? super T,? super T> isDominator)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a collector which collects input elements into `List` removing the elements following their dominator element.
`static <T> Collector<T,?,java.util.List<T>>`	`filtering(Predicate<? super T> predicate)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which filters input elements by the supplied predicate, collecting them to the list.
`static <T,A,R> Collector<T,?,R>`	`filtering(Predicate<? super T> predicate, Collector<? super T,A,R> downstream)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which passes only those elements to the specified downstream collector which match given predicate.
`static <T,U> Collector<T,?,java.util.List<U>>`	`flatMapping(Function<? super T,? extends Stream<? extends U>> mapper)`
`static <T,U,A,R> Collector<T,?,R>`	`flatMapping(Function<? super T,? extends Stream<? extends U>> mapper, Collector<? super U,A,R> downstream)`
`static <T,K> Collector<T,?,java.util.Map<K,java.util.List<T>>>`	`groupingBy(Function<? super T,? extends K> classifier)` Returns a `Collector` 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> Collector<T,?,java.util.Map<K,D>>`	`groupingBy(Function<? super T,? extends K> classifier, Collector<? super T,A,D> downstream)` Returns a `Collector` 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 `Collector`.
`static <T,K,A,D,M extends java.util.Map<K,D>> Collector<T,?,M>`	`groupingBy(Function<? super T,? extends K> classifier, Collector<? super T,A,D> downstream, Supplier<M> mapFactory)` Returns a `Collector` 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 `Collector`.
`static <T,K,M extends java.util.Map<K,java.util.List<T>>> Collector<T,?,M>`	`groupingBy(Function<? super T,? extends K> classifier, Supplier<M> mapFactory)`
`static <T,K> Collector<T,?,java.util.concurrent.ConcurrentMap<K,java.util.List<T>>>`	`groupingByConcurrent(Function<? super T,? extends K> classifier)` Returns a concurrent `Collector` implementing a "group by" operation on input elements of type `T`, grouping elements according to a classification function.
`static <T,K,A,D> Collector<T,?,java.util.concurrent.ConcurrentMap<K,D>>`	`groupingByConcurrent(Function<? super T,? extends K> classifier, Collector<? super T,A,D> downstream)` Returns a concurrent `Collector` 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 `Collector`.
`static <T,K,A,D,M extends java.util.concurrent.ConcurrentMap<K,D>> Collector<T,?,M>`	`groupingByConcurrent(Function<? super T,? extends K> classifier, Collector<? super T,A,D> downstream, Supplier<M> mapFactory)` Returns a concurrent `Collector` 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 `Collector`.
`static <T,K,M extends java.util.concurrent.ConcurrentMap<K,java.util.List<T>>> Collector<T,?,M>`	`groupingByConcurrent(Function<? super T,? extends K> classifier, Supplier<M> mapFactory)`
`static Collector<java.lang.CharSequence,?,java.lang.String>`	`joining()` Returns a `Collector` that concatenates the input elements into a `String`, in encounter order.
`static Collector<java.lang.CharSequence,?,java.lang.String>`	`joining(java.lang.CharSequence delimiter)` Returns a `Collector` that concatenates the input elements, separated by the specified delimiter, in encounter order.
`static Collector<java.lang.CharSequence,?,java.lang.String>`	`joining(java.lang.CharSequence delimiter, java.lang.CharSequence prefix, java.lang.CharSequence suffix)` Returns a `Collector` that concatenates the input elements, separated by the specified delimiter, with the specified prefix and suffix, in encounter order.
`static <T> Collector<T,?,java.util.List<T>>`	`last(int n)`
`static <T,U> Collector<T,?,java.util.List<U>>`	`mapping(Function<? super T,? extends U> mapper)`
`static <T,U,A,R> Collector<T,?,R>`	`mapping(Function<? super T,? extends U> mapper, Collector<? super U,A,R> downstream)` Adapts a `Collector` 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 extends java.lang.Comparable> Collector<T,?,Nullable<T>>`	`max()`
`static <T extends java.lang.Comparable> Collector<T,?,java.util.List<T>>`	`maxAll()` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which finds all the elements which are equal to each other and bigger than any other element according to the natural order.
`static <T extends java.lang.Comparable,A,D> Collector<T,?,D>`	`maxAll(Collector<T,A,D> downstream)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which finds all the elements which are equal to each other and bigger than any other element according to the natural order.
`static <T> Collector<T,?,java.util.List<T>>`	`maxAll(java.util.Comparator<? super T> comparator)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which finds all the elements which are equal to each other and bigger than any other element according to the specified `Comparator`.
`static <T,A,D> Collector<T,?,D>`	`maxAll(java.util.Comparator<? super T> comparator, Collector<? super T,A,D> downstream)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which finds all the elements which are equal to each other and bigger than any other element according to the specified `Comparator`.
`static <T> Collector<T,?,java.util.List<T>>`	`maxAll(java.util.Comparator<? super T> comparator, int atMostSize)`
`static <T> Collector<T,?,Nullable<T>>`	`maxBy(java.util.Comparator<? super T> comparator)` Returns a `Collector` that produces the maximal element according to a given `Comparator`, described as an `Nullable<T>`.
`static <T> Collector<T,?,T>`	`maxByOrGet(java.util.Comparator<? super T> comparator, Supplier<? extends T> other)`
`static <T,X extends java.lang.RuntimeException> Collector<T,?,T>`	`maxByOrThrow(java.util.Comparator<? super T> comparator, Supplier<? extends X> exceptionSupplier)`
`static <T extends java.lang.Comparable> Collector<T,?,Nullable<T>>`	`min()`
`static <T extends java.lang.Comparable> Collector<T,?,java.util.List<T>>`	`minAll()` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which finds all the elements which are equal to each other and smaller than any other element according to the natural order.
`static <T extends java.lang.Comparable,A,D> Collector<T,?,D>`	`minAll(Collector<T,A,D> downstream)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which finds all the elements which are equal to each other and smaller than any other element according to the natural order.
`static <T> Collector<T,?,java.util.List<T>>`	`minAll(java.util.Comparator<? super T> comparator)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which finds all the elements which are equal to each other and smaller than any other element according to the specified `Comparator`.
`static <T,A,D> Collector<T,?,D>`	`minAll(java.util.Comparator<? super T> comparator, Collector<T,A,D> downstream)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which finds all the elements which are equal to each other and smaller than any other element according to the specified `Comparator`.
`static <T> Collector<T,?,java.util.List<T>>`	`minAll(java.util.Comparator<? super T> comparator, int atMostSize)`
`static <T> Collector<T,?,Nullable<T>>`	`minBy(java.util.Comparator<? super T> comparator)` Returns a `Collector` that produces the minimal element according to a given `Comparator`, described as an `Nullable<T>`.
`static <T> Collector<T,?,T>`	`minByOrGet(java.util.Comparator<? super T> comparator, Supplier<? extends T> other)`
`static <T,X extends java.lang.RuntimeException> Collector<T,?,T>`	`minByOrThrow(java.util.Comparator<? super T> comparator, Supplier<? extends X> exceptionSupplier)`
`static <T,R> Collector<T,?,R>`	`minMax(java.util.Comparator<? super T> comparator, BiFunction<? super Nullable<T>,? super Nullable<T>,? extends R> finisher)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which finds the minimal and maximal element according to the supplied comparator, then applies finisher function to them producing the final result.
`static <T,A1,A2,R1,R2,R> Collector<T,?,R>`	`pairing(Collector<? super T,A1,R1> c1, Collector<? super T,A2,R2> c2, BiFunction<? super R1,? super R2,? extends R> finisher)` It's copied from StreamEx: https://github.com/amaembo/streamex Returns a `Collector` which aggregates the results of two supplied collectors using the supplied finisher function.
`static <T> Collector<T,?,java.util.Map<java.lang.Boolean,java.util.List<T>>>`	`partitioningBy(Predicate<? super T> predicate)` Returns a `Collector` which partitions the input elements according to a `Predicate`, and organizes them into a `Map<Boolean, List<T>>`.
`static <T,D,A> Collector<T,?,java.util.Map<java.lang.Boolean,D>>`	`partitioningBy(Predicate<? super T> predicate, Collector<? super T,A,D> downstream)` Returns a `Collector` which partitions the input elements according to a `Predicate`, reduces the values in each partition according to another `Collector`, and organizes them into a `Map<Boolean, D>` whose values are the result of the downstream reduction.
`static <T> Collector<T,?,Nullable<T>>`	`reducing(BinaryOperator<T> op)` Returns a `Collector` which performs a reduction of its input elements under a specified `BinaryOperator`.
`static <T,U> Collector<T,?,Nullable<U>>`	`reducing(Function<? super T,? extends U> mapper, BinaryOperator<U> op)`
`static <T> Collector<T,?,T>`	`reducing(T identity, BinaryOperator<T> op)` Returns a `Collector` which performs a reduction of its input elements under a specified `BinaryOperator` using the provided identity.
`static <T,U> Collector<T,?,U>`	`reducing(U identity, Function<? super T,? extends U> mapper, BinaryOperator<U> op)` Returns a `Collector` which performs a reduction of its input elements under a specified mapping function and `BinaryOperator`.
`static <T> Collector<T,?,T>`	`reducingOrGet(BinaryOperator<T> op, Supplier<? extends T> other)`
`static <T,U> Collector<T,?,U>`	`reducingOrGet(Function<? super T,? extends U> mapper, BinaryOperator<U> op, Supplier<? extends U> other)`
`static <T,X extends java.lang.RuntimeException> Collector<T,?,T>`	`reducingOrThrow(BinaryOperator<T> op, Supplier<? extends X> exceptionSupplier)`
`static <T,U,X extends java.lang.RuntimeException> Collector<T,?,U>`	`reducingOrThrow(Function<? super T,? extends U> mapper, BinaryOperator<U> op, Supplier<? extends X> exceptionSupplier)`
`static <T> Collector<T,?,com.landawn.abacus.util.ByteSummaryStatistics>`	`summarizingByte(ToByteFunction<? super T> mapper)`
`static <T> Collector<T,?,com.landawn.abacus.util.CharSummaryStatistics>`	`summarizingChar(ToCharFunction<? super T> mapper)`
`static <T> Collector<T,?,DoubleSummaryStatistics>`	`summarizingDouble(ToDoubleFunction<? super T> mapper)` Returns a `Collector` which applies an `double`-producing mapping function to each input element, and returns summary statistics for the resulting values.
`static <T> Collector<T,?,com.landawn.abacus.util.FloatSummaryStatistics>`	`summarizingFloat(ToFloatFunction<? super T> mapper)`
`static <T> Collector<T,?,IntSummaryStatistics>`	`summarizingInt(ToIntFunction<? super T> mapper)` Returns a `Collector` which applies an `int`-producing mapping function to each input element, and returns summary statistics for the resulting values.
`static <T> Collector<T,?,LongSummaryStatistics>`	`summarizingLong(ToLongFunction<? super T> mapper)` Returns a `Collector` which applies an `long`-producing mapping function to each input element, and returns summary statistics for the resulting values.
`static <T> Collector<T,?,com.landawn.abacus.util.ShortSummaryStatistics>`	`summarizingShort(ToShortFunction<? super T> mapper)`
`static <T> Collector<T,?,java.lang.Double>`	`summingDouble(ToDoubleFunction<? super T> mapper)` Returns a `Collector` that produces the sum of a double-valued function applied to the input elements.
`static <T> Collector<T,?,OptionalDouble>`	`summingDouble2(ToDoubleFunction<? super T> mapper)`
`static <T> Collector<T,?,java.lang.Integer>`	`summingInt(ToIntFunction<? super T> mapper)` Returns a `Collector` that produces the sum of a integer-valued function applied to the input elements.
`static <T> Collector<T,?,OptionalInt>`	`summingInt2(ToIntFunction<? super T> mapper)`
`static <T> Collector<T,?,java.lang.Long>`	`summingLong(ToLongFunction<? super T> mapper)` Returns a `Collector` that produces the sum of a long-valued function applied to the input elements.
`static <T> Collector<T,?,OptionalLong>`	`summingLong2(ToLongFunction<? super T> mapper)`
`static <T> Collector<T,?,java.lang.Object[]>`	`toArray()`
`static <T,A> Collector<T,?,A[]>`	`toArray(Supplier<A[]> arraySupplier)`
`static <T,K,U> Collector<T,?,BiMap<K,U>>`	`toBiMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper)`
`static <T,K,U> Collector<T,?,BiMap<K,U>>`	`toBiMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, BinaryOperator<U> mergeFunction)`
`static <T,K,U> Collector<T,?,BiMap<K,U>>`	`toBiMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, BinaryOperator<U> mergeFunction, Supplier<BiMap<K,U>> mapFactory)`
`static <T,K,U> Collector<T,?,BiMap<K,U>>`	`toBiMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, Supplier<BiMap<K,U>> mapFactory)`
`static Collector<java.lang.Boolean,?,boolean[]>`	`toBooleanArray()`
`static Collector<java.lang.Boolean,?,BooleanList>`	`toBooleanList()`
`static Collector<java.lang.Byte,?,byte[]>`	`toByteArray()`
`static Collector<java.lang.Byte,?,ByteList>`	`toByteList()`
`static Collector<java.lang.Character,?,char[]>`	`toCharArray()`
`static Collector<java.lang.Character,?,CharList>`	`toCharList()`
`static <T,C extends java.util.Collection<T>> Collector<T,?,C>`	`toCollection(Supplier<C> collectionFactory)` Returns a `Collector` that accumulates the input elements into a new `Collection`, in encounter order.
`static <T,C extends java.util.Collection<T>> Collector<T,?,C>`	`toCollection(Supplier<C> collectionFactory, int atMostSize)`
`static <T,K,U> Collector<T,?,java.util.concurrent.ConcurrentMap<K,U>>`	`toConcurrentMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper)` Returns a concurrent `Collector` that accumulates elements into a `ConcurrentMap` whose keys and values are the result of applying the provided mapping functions to the input elements.
`static <T,K,U> Collector<T,?,java.util.concurrent.ConcurrentMap<K,U>>`	`toConcurrentMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, BinaryOperator<U> mergeFunction)` Returns a concurrent `Collector` that accumulates elements into a `ConcurrentMap` whose keys and values are the result of applying the provided mapping functions to the input elements.
`static <T,K,U,M extends java.util.concurrent.ConcurrentMap<K,U>> Collector<T,?,M>`	`toConcurrentMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, BinaryOperator<U> mergeFunction, Supplier<M> mapFactory)` Returns a concurrent `Collector` that accumulates elements into a `ConcurrentMap` whose keys and values are the result of applying the provided mapping functions to the input elements.
`static <T,K,U,M extends java.util.concurrent.ConcurrentMap<K,U>> Collector<T,?,M>`	`toConcurrentMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, Supplier<M> mapFactory)`
`static <T> Collector<T,?,DataSet>`	`toDataSet()`
`static <T> Collector<T,?,DataSet>`	`toDataSet(java.util.List<java.lang.String> columnNames)`
`static <T> Collector<T,?,java.util.Deque<T>>`	`toDeque()`
`static Collector<java.lang.Double,?,double[]>`	`toDoubleArray()`
`static Collector<java.lang.Double,?,DoubleList>`	`toDoubleList()`
`static Collector<java.lang.Float,?,float[]>`	`toFloatArray()`
`static Collector<java.lang.Float,?,FloatList>`	`toFloatList()`
`static <T> Collector<T,?,ImmutableList<T>>`	`toImmutableList()`
`static <K,V> Collector<java.util.Map.Entry<K,V>,?,ImmutableMap<K,V>>`	`toImmutableMap()`
`static <K,V> Collector<java.util.Map.Entry<K,V>,?,ImmutableMap<K,V>>`	`toImmutableMap(BinaryOperator<V> mergeFunction)`
`static <T,K,U> Collector<T,?,ImmutableMap<K,U>>`	`toImmutableMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper)`
`static <T,K,U> Collector<T,?,ImmutableMap<K,U>>`	`toImmutableMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, BinaryOperator<U> mergeFunction)`
`static <T> Collector<T,?,ImmutableSet<T>>`	`toImmutableSet()`
`static Collector<java.lang.Integer,?,int[]>`	`toIntArray()`
`static Collector<java.lang.Integer,?,IntList>`	`toIntList()`
`static <T,K,U> Collector<T,?,java.util.LinkedHashMap<K,U>>`	`toLinkedHashMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper)`
`static <T,K,U> Collector<T,?,java.util.LinkedHashMap<K,U>>`	`toLinkedHashMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, BinaryOperator<U> mergeFunction)`
`static <T> Collector<T,?,java.util.LinkedHashSet<T>>`	`toLinkedHashSet()`
`static <T> Collector<T,?,java.util.LinkedList<T>>`	`toLinkedList()`
`static <T> Collector<T,?,java.util.List<T>>`	`toList()` Returns a `Collector` that accumulates the input elements into a new `List`.
`static <T> Collector<T,?,java.util.List<T>>`	`toList(int atMostSize)`
`static Collector<java.lang.Long,?,long[]>`	`toLongArray()`
`static Collector<java.lang.Long,?,LongList>`	`toLongList()`
`static <T> Collector<T,?,LongMultiset<T>>`	`toLongMultiset()`
`static <T> Collector<T,?,LongMultiset<T>>`	`toLongMultiset(Supplier<LongMultiset<T>> supplier)`
`static <K,V> Collector<java.util.Map.Entry<K,V>,?,java.util.Map<K,V>>`	`toMap()`
`static <K,V> Collector<java.util.Map.Entry<K,V>,?,java.util.Map<K,V>>`	`toMap(BinaryOperator<V> mergeFunction)`
`static <K,V,M extends java.util.Map<K,V>> Collector<java.util.Map.Entry<K,V>,?,M>`	`toMap(BinaryOperator<V> mergeFunction, Supplier<M> mapFactory)`
`static <T,K,U> Collector<T,?,java.util.Map<K,U>>`	`toMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper)` Returns a `Collector` 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> Collector<T,?,java.util.Map<K,U>>`	`toMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, BinaryOperator<U> mergeFunction)` Returns a `Collector` 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 java.util.Map<K,U>> Collector<T,?,M>`	`toMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, BinaryOperator<U> mergeFunction, Supplier<M> mapFactory)` Returns a `Collector` 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 java.util.Map<K,U>> Collector<T,?,M>`	`toMap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, Supplier<M> mapFactory)`
`static <K,V,M extends java.util.Map<K,V>> Collector<java.util.Map.Entry<K,V>,?,M>`	`toMap(Supplier<M> mapFactory)`
`static <K,E> Collector<java.util.Map.Entry<? extends K,? extends E>,?,ListMultimap<K,E>>`	`toMultimap()`
`static <T,K> Collector<T,?,ListMultimap<K,T>>`	`toMultimap(Function<? super T,? extends K> keyExtractor)`
`static <T,K,U> Collector<T,?,ListMultimap<K,U>>`	`toMultimap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper)`
`static <T,K,U,V extends java.util.Collection<U>,M extends Multimap<K,U,V>> Collector<T,?,M>`	`toMultimap(Function<? super T,? extends K> keyExtractor, Function<? super T,? extends U> valueMapper, Supplier<M> mapFactory)`
`static <T,K,V extends java.util.Collection<T>,M extends Multimap<K,T,V>> Collector<T,?,M>`	`toMultimap(Function<? super T,? extends K> keyExtractor, Supplier<M> mapFactory)`
`static <K,E,V extends java.util.Collection<E>,M extends Multimap<K,E,V>> Collector<java.util.Map.Entry<? extends K,? extends E>,?,M>`	`toMultimap(Supplier<M> mapFactory)`
`static <T> Collector<T,?,Multiset<T>>`	`toMultiset()`
`static <T> Collector<T,?,Multiset<T>>`	`toMultiset(Supplier<Multiset<T>> supplier)`
`static <T> Collector<T,?,java.util.Queue<T>>`	`toQueue()`
`static <T> Collector<T,?,java.util.Set<T>>`	`toSet()` Returns a `Collector` that accumulates the input elements into a new `Set`.
`static <T> Collector<T,?,java.util.Set<T>>`	`toSet(int atMostSize)`
`static Collector<java.lang.Short,?,short[]>`	`toShortArray()`
`static Collector<java.lang.Short,?,ShortList>`	`toShortList()`

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

- Method Detail
 - toCollection
```
public static <T,C extends java.util.Collection<T>> Collector<T,?,C> toCollection(Supplier<C> collectionFactory)
```
 Returns a Collector 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 Supplier which returns a new, empty Collection of the appropriate type
 
 Returns:
 
 a Collector which collects all the input elements into a Collection, in encounter order
 - toList
```
public static <T> Collector<T,?,java.util.List<T>> toList()
```
 Returns a Collector 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(Supplier).
 
 Type Parameters:
 
 T - the type of the input elements
 
 Returns:
 
 a Collector which collects all the input elements into a List, in encounter order
 - toLinkedList
```
public static <T> Collector<T,?,java.util.LinkedList<T>> toLinkedList()
```
 - toImmutableList
```
public static <T> Collector<T,?,ImmutableList<T>> toImmutableList()
```
 - toSet
```
public static <T> Collector<T,?,java.util.Set<T>> toSet()
```
 Returns a Collector 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(Supplier).
 This is an unordered Collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Returns:
 
 a Collector which collects all the input elements into a Set
 - toLinkedHashSet
```
public static <T> Collector<T,?,java.util.LinkedHashSet<T>> toLinkedHashSet()
```
 - toImmutableSet
```
public static <T> Collector<T,?,ImmutableSet<T>> toImmutableSet()
```
 - toQueue
```
public static <T> Collector<T,?,java.util.Queue<T>> toQueue()
```
 - toDeque
```
public static <T> Collector<T,?,java.util.Deque<T>> toDeque()
```
 - toCollection
```
public static <T,C extends java.util.Collection<T>> Collector<T,?,C> toCollection(Supplier<C> collectionFactory,
 int atMostSize)
```
 - toList
```
public static <T> Collector<T,?,java.util.List<T>> toList(int atMostSize)
```
 - toSet
```
public static <T> Collector<T,?,java.util.Set<T>> toSet(int atMostSize)
```
 - toMultiset
```
public static <T> Collector<T,?,Multiset<T>> toMultiset()
```
 - toMultiset
```
public static <T> Collector<T,?,Multiset<T>> toMultiset(Supplier<Multiset<T>> supplier)
```
 - toLongMultiset
```
public static <T> Collector<T,?,LongMultiset<T>> toLongMultiset()
```
 - toLongMultiset
```
public static <T> Collector<T,?,LongMultiset<T>> toLongMultiset(Supplier<LongMultiset<T>> supplier)
```
 - toArray
```
public static <T> Collector<T,?,java.lang.Object[]> toArray()
```
 - toArray
```
public static <T,A> Collector<T,?,A[]> toArray(Supplier<A[]> arraySupplier)
```
 - toBooleanList
```
public static Collector<java.lang.Boolean,?,BooleanList> toBooleanList()
```
 - toBooleanArray
```
public static Collector<java.lang.Boolean,?,boolean[]> toBooleanArray()
```
 - toCharList
```
public static Collector<java.lang.Character,?,CharList> toCharList()
```
 - toCharArray
```
public static Collector<java.lang.Character,?,char[]> toCharArray()
```
 - toByteList
```
public static Collector<java.lang.Byte,?,ByteList> toByteList()
```
 - toByteArray
```
public static Collector<java.lang.Byte,?,byte[]> toByteArray()
```
 - toShortList
```
public static Collector<java.lang.Short,?,ShortList> toShortList()
```
 - toShortArray
```
public static Collector<java.lang.Short,?,short[]> toShortArray()
```
 - toIntList
```
public static Collector<java.lang.Integer,?,IntList> toIntList()
```
 - toIntArray
```
public static Collector<java.lang.Integer,?,int[]> toIntArray()
```
 - toLongList
```
public static Collector<java.lang.Long,?,LongList> toLongList()
```
 - toLongArray
```
public static Collector<java.lang.Long,?,long[]> toLongArray()
```
 - toFloatList
```
public static Collector<java.lang.Float,?,FloatList> toFloatList()
```
 - toFloatArray
```
public static Collector<java.lang.Float,?,float[]> toFloatArray()
```
 - toDoubleList
```
public static Collector<java.lang.Double,?,DoubleList> toDoubleList()
```
 - toDoubleArray
```
public static Collector<java.lang.Double,?,double[]> toDoubleArray()
```
 - last
```
public static <T> Collector<T,?,java.util.List<T>> last(int n)
```
 Parameters:
 
 n -
 
 Returns:
 
 Throws:
 
 java.lang.UnsupportedOperationException - it's used in parallel stream.
 - joining
```
public static Collector<java.lang.CharSequence,?,java.lang.String> joining()
```
 Returns a Collector that concatenates the input elements into a String, in encounter order.
 
 Returns:
 
 a Collector that concatenates the input elements into a String, in encounter order
 - joining
```
public static Collector<java.lang.CharSequence,?,java.lang.String> joining(java.lang.CharSequence delimiter)
```
 Returns a Collector 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 Collector which concatenates CharSequence elements, separated by the specified delimiter, in encounter order
 - joining
```
public static Collector<java.lang.CharSequence,?,java.lang.String> joining(java.lang.CharSequence delimiter,
 java.lang.CharSequence prefix,
 java.lang.CharSequence suffix)
```
 Returns a Collector 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 Collector which concatenates CharSequence elements, separated by the specified delimiter, in encounter order
 - filtering
```
public static <T> Collector<T,?,java.util.List<T>> filtering(Predicate<? super T> predicate)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which filters input elements by the supplied predicate, collecting them to the list.
 This method behaves like filtering(predicate, Collectors.toList()).
 There are no guarantees on the type, mutability, serializability, or thread-safety of the List returned.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 predicate - a filter function to be applied to the input elements
 
 Returns:
 
 a collector which applies the predicate to the input elements and collects the elements for which predicate returned true to the List
 
 Since:
 
 0.6.0
 
 See Also:
 
 filtering(Predicate, Collector)
 - filtering
```
public static <T,A,R> Collector<T,?,R> filtering(Predicate<? super T> predicate,
 Collector<? super T,A,R> downstream)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which passes only those elements to the specified downstream collector which match given predicate.
 This method returns a short-circuiting collector if downstream collector is short-circuiting.
 The operation performed by the returned collector is equivalent to stream.filter(predicate).collect(downstream). This collector is mostly useful as a downstream collector in cascaded operation involving pairing(Collector, Collector, BiFunction) collector.
 This method is similar to Collectors.filtering method which appears in JDK 9. However when downstream collector is short-circuiting , this method will also return a short-circuiting collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 A - intermediate accumulation type of the downstream collector
 
 R - result type of collector
 
 Parameters:
 
 predicate - a filter function to be applied to the input elements
 
 downstream - a collector which will accept filtered values
 
 Returns:
 
 a collector which applies the predicate to the input elements and provides the elements for which predicate returned true to the downstream collector
 
 Since:
 
 0.4.0
 
 See Also:
 
 pairing(Collector, Collector, BiFunction)
 - mapping
```
public static <T,U> Collector<T,?,java.util.List> mapping(Function<? super T,? extends U> mapper)
```
 - mapping
```
public static <T,U,A,R> Collector<T,?,R> mapping(Function<? super T,? extends U> mapper,
 Collector<? super U,A,R> downstream)
```
 Adapts a Collector 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
 - flatMapping
```
public static <T,U> Collector<T,?,java.util.List> flatMapping(Function<? super T,? extends Stream<? extends U>> mapper)
```
 - flatMapping
```
public static <T,U,A,R> Collector<T,?,R> flatMapping(Function<? super T,? extends Stream<? extends U>> mapper,
 Collector<? super U,A,R> downstream)
```
 - collectingAndThen
```
public static <T,A,R,RR> Collector<T,A,RR> collectingAndThen(Collector<T,A,R> downstream,
 Function<R,RR> finisher)
```
 Adapts a Collector 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
 - distinctBy
```
public static <T> Collector<T,?,java.util.List<T>> distinctBy(Function<? super T,?> mapper)
```
 Returns a Collector which collects into the List the input elements for which given mapper function returns distinct results.
 For ordered source the order of collected elements is preserved. If the same result is returned by mapper function for several elements, only the first element is included into the resulting list.
 There are no guarantees on the type, mutability, serializability, or thread-safety of the List returned.
 The operation performed by the returned collector is equivalent to stream.distinct(mapper).toList(), but may work faster.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - a function which classifies input elements.
 
 Returns:
 
 a collector which collects distinct elements to the List.
 
 Since:
 
 0.3.8
 - distinctCount
```
public static <T> Collector<T,?,java.lang.Integer> distinctCount(Function<? super T,?> mapper)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which counts a number of distinct values the mapper function returns for the stream elements.
 The operation performed by the returned collector is equivalent to stream.map(mapper).distinct().count(). This collector is mostly useful as a downstream collector.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 mapper - a function which classifies input elements.
 
 Returns:
 
 a collector which counts a number of distinct classes the mapper function returns for the stream elements.
 - counting
```
public static <T> Collector<T,?,java.lang.Long> counting()
```
 Returns a Collector 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 Collector that counts the input elements
 - countingInt
```
public static <T> Collector<T,?,java.lang.Integer> countingInt()
```
 - min
```
public static <T extends java.lang.Comparable> Collector<T,?,Nullable<T>> min()
```
 - minBy
```
public static <T> Collector<T,?,Nullable<T>> minBy(java.util.Comparator<? super T> comparator)
```
 Returns a Collector that produces the minimal element according to a given Comparator, described as an Nullable<T>.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 comparator - a Comparator for comparing elements
 
 Returns:
 
 a Collector that produces the minimal value
 - minByOrGet
```
public static <T> Collector<T,?,T> minByOrGet(java.util.Comparator<? super T> comparator,
 Supplier<? extends T> other)
```
 - minByOrThrow
```
public static <T,X extends java.lang.RuntimeException> Collector<T,?,T> minByOrThrow(java.util.Comparator<? super T> comparator,
 Supplier<? extends X> exceptionSupplier)
```
 - max
```
public static <T extends java.lang.Comparable> Collector<T,?,Nullable<T>> max()
```
 - maxBy
```
public static <T> Collector<T,?,Nullable<T>> maxBy(java.util.Comparator<? super T> comparator)
```
 Returns a Collector that produces the maximal element according to a given Comparator, described as an Nullable<T>.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 comparator - a Comparator for comparing elements
 
 Returns:
 
 a Collector that produces the maximal value
 - maxByOrGet
```
public static <T> Collector<T,?,T> maxByOrGet(java.util.Comparator<? super T> comparator,
 Supplier<? extends T> other)
```
 - maxByOrThrow
```
public static <T,X extends java.lang.RuntimeException> Collector<T,?,T> maxByOrThrow(java.util.Comparator<? super T> comparator,
 Supplier<? extends X> exceptionSupplier)
```
 - pairing
```
public static <T,A1,A2,R1,R2,R> Collector<T,?,R> pairing(Collector<? super T,A1,R1> c1,
 Collector<? super T,A2,R2> c2,
 BiFunction<? super R1,? super R2,? extends R> finisher)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which aggregates the results of two supplied collectors using the supplied finisher function.
 This method returns a short-circuiting collector if both downstream collectors are short-circuiting. The collection might stop when both downstream collectors report that the collection is complete.
 
 Type Parameters:
 
 T - the type of the input elements
 
 A1 - the intermediate accumulation type of the first collector
 
 A2 - the intermediate accumulation type of the second collector
 
 R1 - the result type of the first collector
 
 R2 - the result type of the second collector
 
 R - the final result type
 
 Parameters:
 
 c1 - the first collector
 
 c2 - the second collector
 
 finisher - the function which merges two results into the single one.
 
 Returns:
 
 a Collector which aggregates the results of two supplied collectors.
 - minMax
```
public static <T,R> Collector<T,?,R> minMax(java.util.Comparator<? super T> comparator,
 BiFunction<? super Nullable<T>,? super Nullable<T>,? extends R> finisher)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which finds the minimal and maximal element according to the supplied comparator, then applies finisher function to them producing the final result.
 This collector produces stable result for ordered stream: if several minimal or maximal elements appear, the collector always selects the first encountered.
 If there are no input elements, the finisher method is not called and empty Optional is returned. Otherwise the finisher result is wrapped into Optional.
 
 Type Parameters:
 
 T - the type of the input elements
 
 R - the type of the result wrapped into Optional
 
 Parameters:
 
 comparator - comparator which is used to find minimal and maximal element
 
 finisher - a BiFunction which takes minimal and maximal element and produces the final result.
 
 Returns:
 
 a Collector which finds minimal and maximal elements.
 - maxAll
```
public static <T,A,D> Collector<T,?,D> maxAll(java.util.Comparator<? super T> comparator,
 Collector<? super T,A,D> downstream)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which finds all the elements which are equal to each other and bigger than any other element according to the specified Comparator. The found elements are reduced using the specified downstream Collector.
 
 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:
 
 comparator - a Comparator to compare the elements
 
 downstream - a Collector implementing the downstream reduction
 
 Returns:
 
 a Collector which finds all the maximal elements.
 
 See Also:
 
 maxAll(Comparator), maxAll(Collector), maxAll()
 - maxAll
```
public static <T> Collector<T,?,java.util.List<T>> maxAll(java.util.Comparator<? super T> comparator)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which finds all the elements which are equal to each other and bigger than any other element according to the specified Comparator. The found elements are collected to List.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 comparator - a Comparator to compare the elements
 
 Returns:
 
 a Collector which finds all the maximal elements and collects them to the List.
 
 See Also:
 
 maxAll(Comparator, Collector), maxAll()
 - maxAll
```
public static <T> Collector<T,?,java.util.List<T>> maxAll(java.util.Comparator<? super T> comparator,
 int atMostSize)
```
 Parameters:
 
 comparator -
 
 atMostSize -
 
 Returns:
 - maxAll
```
public static <T extends java.lang.Comparable,A,D> Collector<T,?,D> maxAll(Collector<T,A,D> downstream)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which finds all the elements which are equal to each other and bigger than any other element according to the natural order. The found elements are reduced using the specified downstream Collector.
 
 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:
 
 downstream - a Collector implementing the downstream reduction
 
 Returns:
 
 a Collector which finds all the maximal elements.
 
 See Also:
 
 maxAll(Comparator, Collector), maxAll(Comparator), maxAll()
 - maxAll
```
public static <T extends java.lang.Comparable> Collector<T,?,java.util.List<T>> maxAll()
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which finds all the elements which are equal to each other and bigger than any other element according to the natural order. The found elements are collected to List.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Returns:
 
 a Collector which finds all the maximal elements and collects them to the List.
 
 See Also:
 
 maxAll(Comparator), maxAll(Collector)
 - minAll
```
public static <T,A,D> Collector<T,?,D> minAll(java.util.Comparator<? super T> comparator,
 Collector<T,A,D> downstream)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which finds all the elements which are equal to each other and smaller than any other element according to the specified Comparator. The found elements are reduced using the specified downstream Collector.
 
 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:
 
 comparator - a Comparator to compare the elements
 
 downstream - a Collector implementing the downstream reduction
 
 Returns:
 
 a Collector which finds all the minimal elements.
 
 See Also:
 
 minAll(Comparator), minAll(Collector), minAll()
 - minAll
```
public static <T> Collector<T,?,java.util.List<T>> minAll(java.util.Comparator<? super T> comparator)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which finds all the elements which are equal to each other and smaller than any other element according to the specified Comparator. The found elements are collected to List.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Parameters:
 
 comparator - a Comparator to compare the elements
 
 Returns:
 
 a Collector which finds all the minimal elements and collects them to the List.
 
 See Also:
 
 minAll(Comparator, Collector), minAll()
 - minAll
```
public static <T> Collector<T,?,java.util.List<T>> minAll(java.util.Comparator<? super T> comparator,
 int atMostSize)
```
 Parameters:
 
 comparator -
 
 atMostSize -
 
 Returns:
 - minAll
```
public static <T extends java.lang.Comparable,A,D> Collector<T,?,D> minAll(Collector<T,A,D> downstream)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which finds all the elements which are equal to each other and smaller than any other element according to the natural order. The found elements are reduced using the specified downstream Collector.
 
 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:
 
 downstream - a Collector implementing the downstream reduction
 
 Returns:
 
 a Collector which finds all the minimal elements.
 
 See Also:
 
 minAll(Comparator, Collector), minAll(Comparator), minAll()
 - minAll
```
public static <T extends java.lang.Comparable> Collector<T,?,java.util.List<T>> minAll()
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which finds all the elements which are equal to each other and smaller than any other element according to the natural order. The found elements are collected to List.
 
 Type Parameters:
 
 T - the type of the input elements
 
 Returns:
 
 a Collector which finds all the minimal elements and collects them to the List.
 
 See Also:
 
 minAll(Comparator), minAll(Collector)
 - summingInt
```
public static <T> Collector<T,?,java.lang.Integer> summingInt(ToIntFunction<? super T> mapper)
```
 Returns a Collector 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 Collector that produces the sum of a derived property
 - summingInt2
```
public static <T> Collector<T,?,OptionalInt> summingInt2(ToIntFunction<? super T> mapper)
```
 - summingLong
```
public static <T> Collector<T,?,java.lang.Long> summingLong(ToLongFunction<? super T> mapper)
```
 Returns a Collector 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 Collector that produces the sum of a derived property
 - summingLong2
```
public static <T> Collector<T,?,OptionalLong> summingLong2(ToLongFunction<? super T> mapper)
```
 - summingDouble
```
public static <T> Collector<T,?,java.lang.Double> summingDouble(ToDoubleFunction<? super T> mapper)
```
 Returns a Collector 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 Collector that produces the sum of a derived property
 - summingDouble2
```
public static <T> Collector<T,?,OptionalDouble> summingDouble2(ToDoubleFunction<? super T> mapper)
```
 - averagingInt
```
public static <T> Collector<T,?,java.lang.Double> averagingInt(ToIntFunction<? super T> mapper)
```
 Returns a Collector 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 Collector that produces the sum of a derived property
 - averagingInt2
```
public static <T> Collector<T,?,OptionalDouble> averagingInt2(ToIntFunction<? super T> mapper)
```
 - averagingLong
```
public static <T> Collector<T,?,java.lang.Double> averagingLong(ToLongFunction<? super T> mapper)
```
 Returns a Collector 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 Collector that produces the sum of a derived property
 - averagingLong2
```
public static <T> Collector<T,?,OptionalDouble> averagingLong2(ToLongFunction<? super T> mapper)
```
 - averagingDouble
```
public static <T> Collector<T,?,java.lang.Double> averagingDouble(ToDoubleFunction<? super T> mapper)
```
 Returns a Collector 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 Collector that produces the sum of a derived property
 - averagingDouble2
```
public static <T> Collector<T,?,OptionalDouble> averagingDouble2(ToDoubleFunction<? super T> mapper)
```
 - summarizingChar
```
public static <T> Collector<T,?,com.landawn.abacus.util.CharSummaryStatistics> summarizingChar(ToCharFunction<? super T> mapper)
```
 - summarizingByte
```
public static <T> Collector<T,?,com.landawn.abacus.util.ByteSummaryStatistics> summarizingByte(ToByteFunction<? super T> mapper)
```
 - summarizingShort
```
public static <T> Collector<T,?,com.landawn.abacus.util.ShortSummaryStatistics> summarizingShort(ToShortFunction<? super T> mapper)
```
 - summarizingInt
```
public static <T> Collector<T,?,IntSummaryStatistics> summarizingInt(ToIntFunction<? super T> mapper)
```
 Returns a Collector 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 Collector implementing the summary-statistics reduction
 
 See Also:
 
 summarizingDouble(ToDoubleFunction), summarizingLong(ToLongFunction)
 - summarizingLong
```
public static <T> Collector<T,?,LongSummaryStatistics> summarizingLong(ToLongFunction<? super T> mapper)
```
 Returns a Collector 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 Collector implementing the summary-statistics reduction
 
 See Also:
 
 summarizingDouble(ToDoubleFunction), summarizingInt(ToIntFunction)
 - summarizingFloat
```
public static <T> Collector<T,?,com.landawn.abacus.util.FloatSummaryStatistics> summarizingFloat(ToFloatFunction<? super T> mapper)
```
 - summarizingDouble
```
public static <T> Collector<T,?,DoubleSummaryStatistics> summarizingDouble(ToDoubleFunction<? super T> mapper)
```
 Returns a Collector 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 Collector implementing the summary-statistics reduction
 
 See Also:
 
 summarizingLong(ToLongFunction), summarizingInt(ToIntFunction)
 - reducing
```
public static <T> Collector<T,?,T> reducing(T identity,
 BinaryOperator<T> op)
```
 Returns a Collector which performs a reduction of its input elements under a specified BinaryOperator 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 BinaryOperator<T> used to reduce the input elements
 
 Returns:
 
 a Collector which implements the reduction operation
 
 See Also:
 
 reducing(BinaryOperator), reducing(Object, Function, BinaryOperator)
 - reducing
```
public static <T> Collector<T,?,Nullable<T>> reducing(BinaryOperator<T> op)
```
 Returns a Collector which performs a reduction of its input elements under a specified BinaryOperator. The result is described as an Nullable<T>.
 
 Type Parameters:
 
 T - element type for the input and output of the reduction
 
 Parameters:
 
 op - a BinaryOperator<T> used to reduce the input elements
 
 Returns:
 
 a Collector which implements the reduction operation
 
 See Also:
 
 reducing(Object, BinaryOperator), reducing(Object, Function, BinaryOperator)
 - reducingOrGet
```
public static <T> Collector<T,?,T> reducingOrGet(BinaryOperator<T> op,
 Supplier<? extends T> other)
```
 - reducingOrThrow
```
public static <T,X extends java.lang.RuntimeException> Collector<T,?,T> reducingOrThrow(BinaryOperator<T> op,
 Supplier<? extends X> exceptionSupplier)
```
 - reducing
```
public static <T,U> Collector<T,?,U> reducing(U identity,
 Function<? super T,? extends U> mapper,
 BinaryOperator op)
```
 Returns a Collector which performs a reduction of its input elements under a specified mapping function and BinaryOperator. This is a generalization of reducing(Object, BinaryOperator) 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 BinaryOperator used to reduce the mapped values
 
 Returns:
 
 a Collector implementing the map-reduce operation
 
 See Also:
 
 reducing(Object, BinaryOperator), reducing(BinaryOperator)
 - reducing
```
public static <T,U> Collector<T,?,Nullable> reducing(Function<? super T,? extends U> mapper,
 BinaryOperator op)
```
 - reducingOrGet
```
public static <T,U> Collector<T,?,U> reducingOrGet(Function<? super T,? extends U> mapper,
 BinaryOperator op,
 Supplier<? extends U> other)
```
 - reducingOrThrow
```
public static <T,U,X extends java.lang.RuntimeException> Collector<T,?,U> reducingOrThrow(Function<? super T,? extends U> mapper,
 BinaryOperator op,
 Supplier<? extends X> exceptionSupplier)
```
 - commonPrefix
```
public static Collector<java.lang.CharSequence,?,java.lang.String> commonPrefix()
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which computes a common prefix of input CharSequence objects returning the result as String. For empty input the empty String is returned.
 The returned Collector handles specially Unicode surrogate pairs: the returned prefix may end with Unicode high-surrogate code unit only if it's not succeeded by Unicode low-surrogate code unit in any of the input sequences. Normally the ending high-surrogate code unit is removed from the prefix.
 This method returns a short-circuiting collector: it may not process all the elements if the common prefix is empty.
 
 Returns:
 
 a Collector which computes a common prefix.
 
 Since:
 
 0.5.0
 - commonSuffix
```
public static Collector<java.lang.CharSequence,?,java.lang.String> commonSuffix()
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a Collector which computes a common suffix of input CharSequence objects returning the result as String. For empty input the empty String is returned.
 The returned Collector handles specially Unicode surrogate pairs: the returned suffix may start with Unicode low-surrogate code unit only if it's not preceded by Unicode high-surrogate code unit in any of the input sequences. Normally the starting low-surrogate code unit is removed from the suffix.
 This method returns a short-circuiting collector: it may not process all the elements if the common suffix is empty.
 
 Returns:
 
 a Collector which computes a common suffix.
 
 Since:
 
 0.5.0
 - dominators
```
public static <T> Collector<T,?,java.util.List<T>> dominators(BiPredicate<? super T,? super T> isDominator)
```
 It's copied from StreamEx: https://github.com/amaembo/streamex
 Returns a collector which collects input elements into List removing the elements following their dominator element. The dominator elements are defined according to given isDominator BiPredicate. The isDominator relation must be transitive (if A dominates over B and B dominates over C, then A also dominates over C).
 This operation is similar to streamEx.collapse(isDominator).toList(). The important difference is that in this method BiPredicate accepts not the adjacent stream elements, but the leftmost element of the series (current dominator) and the current element.
 For example, consider the stream of numbers:
```
 StreamEx<Integer> stream = StreamEx.of(1, 5, 3, 4, 2, 7);
 
```
 Using stream.collapse((a, b) -> a >= b).toList() you will get the numbers which are bigger than their immediate predecessor ( [1, 5, 4, 7]), because (3, 4) pair is not collapsed. However using stream.collect(dominators((a, b) -> a >= b)) you will get the numbers which are bigger than any predecessor ([1, 5, 7]) as 5 is the dominator element for the subsequent 3, 4 and 2.
 Type Parameters:
 
 T - type of the input elements.
 
 Parameters:
 
 isDominator - a non-interfering, stateless, transitive BiPredicate which returns true if the first argument is the dominator for the second argument.
 
 Returns:
 
 a collector which collects input element into List leaving only dominator elements.
 
 Throws:
 
 java.lang.UnsupportedOperationException - it's used in parallel stream.
 
 Since:
 
 0.5.1
 - groupingBy
```
public static <T,K> Collector<T,?,java.util.Map<K,java.util.List<T>>> groupingBy(Function<? super T,? extends K> classifier)
```
 Returns a Collector 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 Collector implementing the group-by operation
 
 See Also:
 
 groupingBy(Function, Collector), groupingBy(Function, Collector, Supplier), groupingByConcurrent(Function)
 - groupingBy
```
public static <T,K,M extends java.util.Map<K,java.util.List<T>>> Collector<T,?,M> groupingBy(Function<? super T,? extends K> classifier,
 Supplier<M> mapFactory)
```
 - groupingBy
```
public static <T,K,A,D> Collector<T,?,java.util.Map<K,D>> groupingBy(Function<? super T,? extends K> classifier,
 Collector<? super T,A,D> downstream)
```
 Returns a Collector 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 Collector.
 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 Collector implementing the downstream reduction
 
 Returns:
 
 a Collector implementing the cascaded group-by operation
 
 See Also:
 
 groupingBy(Function), groupingBy(Function, Collector, Supplier), groupingByConcurrent(Function, Collector)
 - groupingBy
```
public static <T,K,A,D,M extends java.util.Map<K,D>> Collector<T,?,M> groupingBy(Function<? super T,? extends K> classifier,
 Collector<? super T,A,D> downstream,
 Supplier<M> mapFactory)
```
 Returns a Collector 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 Collector. 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 Collector implementing the downstream reduction
 
 mapFactory - a function which, when called, produces a new empty Map of the desired type
 
 Returns:
 
 a Collector implementing the cascaded group-by operation
 
 See Also:
 
 groupingBy(Function, Collector), groupingBy(Function), groupingByConcurrent(Function, Collector, Supplier)
 - groupingByConcurrent
```
public static <T,K> Collector<T,?,java.util.concurrent.ConcurrentMap<K,java.util.List<T>>> groupingByConcurrent(Function<? super T,? extends K> classifier)
```
 Returns a concurrent Collector implementing a "group by" operation on input elements of type T, grouping elements according to a classification function.
 This is a concurrent and unordered Collector.
 The classification function maps elements to some key type K. The collector produces a ConcurrentMap<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, or serializability of the Map or List objects returned, or of the thread-safety of the List objects returned.
 
 Type Parameters:
 
 T - the type of the input elements
 
 K - the type of the keys
 
 Parameters:
 
 classifier - a classifier function mapping input elements to keys
 
 Returns:
 
 a concurrent, unordered Collector implementing the group-by operation
 
 See Also:
 
 groupingBy(Function), groupingByConcurrent(Function, Collector), groupingByConcurrent(Function, Collector, Supplier)
 - groupingByConcurrent
```
public static <T,K,M extends java.util.concurrent.ConcurrentMap<K,java.util.List<T>>> Collector<T,?,M> groupingByConcurrent(Function<? super T,? extends K> classifier,
 Supplier<M> mapFactory)
```
 - groupingByConcurrent
```
public static <T,K,A,D> Collector<T,?,java.util.concurrent.ConcurrentMap<K,D>> groupingByConcurrent(Function<? super T,? extends K> classifier,
 Collector<? super T,A,D> downstream)
```
 Returns a concurrent Collector 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 Collector.
 This is a concurrent and unordered Collector.
 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:
```
 ConcurrentMap<City, Set<String>> namesByCity
 = people.stream().collect(groupingByConcurrent(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 Collector implementing the downstream reduction
 
 Returns:
 
 a concurrent, unordered Collector implementing the cascaded group-by operation
 
 See Also:
 
 groupingBy(Function, Collector), groupingByConcurrent(Function), groupingByConcurrent(Function, Collector, Supplier)
 - groupingByConcurrent
```
public static <T,K,A,D,M extends java.util.concurrent.ConcurrentMap<K,D>> Collector<T,?,M> groupingByConcurrent(Function<? super T,? extends K> classifier,
 Collector<? super T,A,D> downstream,
 Supplier<M> mapFactory)
```
 Returns a concurrent Collector 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 Collector. The ConcurrentMap produced by the Collector is created with the supplied factory function.
 This is a concurrent and unordered Collector.
 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:
```
 ConcurrentMap<City, Set<String>> namesByCity
 = people.stream().collect(groupingBy(Person::getCity, ConcurrentSkipListMap::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 ConcurrentMap
 
 Parameters:
 
 classifier - a classifier function mapping input elements to keys
 
 downstream - a Collector implementing the downstream reduction
 
 mapFactory - a function which, when called, produces a new empty ConcurrentMap of the desired type
 
 Returns:
 
 a concurrent, unordered Collector implementing the cascaded group-by operation
 
 See Also:
 
 groupingByConcurrent(Function), groupingByConcurrent(Function, Collector), groupingBy(Function, Collector, Supplier)
 - partitioningBy
```
public static <T> Collector<T,?,java.util.Map<java.lang.Boolean,java.util.List<T>>> partitioningBy(Predicate<? super T> predicate)
```
 Returns a Collector which partitions the input elements according to a Predicate, 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 Collector implementing the partitioning operation
 
 See Also:
 
 partitioningBy(Predicate, Collector)
 - partitioningBy
```
public static <T,D,A> Collector<T,?,java.util.Map<java.lang.Boolean,D>> partitioningBy(Predicate<? super T> predicate,
 Collector<? super T,A,D> downstream)
```
 Returns a Collector which partitions the input elements according to a Predicate, reduces the values in each partition according to another Collector, 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 Collector implementing the downstream reduction
 
 Returns:
 
 a Collector implementing the cascaded partitioning operation
 
 See Also:
 
 partitioningBy(Predicate)
 - toMap
```
public static <K,V> Collector<java.util.Map.Entry<K,V>,?,java.util.Map<K,V>> toMap()
```
 - toMap
```
public static <K,V> Collector<java.util.Map.Entry<K,V>,?,java.util.Map<K,V>> toMap(BinaryOperator<V> mergeFunction)
```
 - toMap
```
public static <K,V,M extends java.util.Map<K,V>> Collector<java.util.Map.Entry<K,V>,?,M> toMap(Supplier<M> mapFactory)
```
 - toMap
```
public static <K,V,M extends java.util.Map<K,V>> Collector<java.util.Map.Entry<K,V>,?,M> toMap(BinaryOperator<V> mergeFunction,
 Supplier<M> mapFactory)
```
 - toMap
```
public static <T,K,U> Collector<T,?,java.util.Map<K,U>> toMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper)
```
 Returns a Collector 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(Function, Function, BinaryOperator) 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:
 
 keyExtractor - a mapping function to produce keys
 
 valueMapper - a mapping function to produce values
 
 Returns:
 
 a Collector which collects elements into a Map whose keys and values are the result of applying mapping functions to the input elements
 
 See Also:
 
 toMap(Function, Function, BinaryOperator), toMap(Function, Function, BinaryOperator, Supplier), toConcurrentMap(Function, Function)
 - toMap
```
public static <T,K,U> Collector<T,?,java.util.Map<K,U>> toMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 BinaryOperator mergeFunction)
```
 Returns a Collector 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:
 
 keyExtractor - 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, BiFunction)
 
 Returns:
 
 a Collector 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(Function, Function), toMap(Function, Function, BinaryOperator, Supplier), toConcurrentMap(Function, Function, BinaryOperator)
 - toMap
```
public static <T,K,U,M extends java.util.Map<K,U>> Collector<T,?,M> toMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 Supplier<M> mapFactory)
```
 - toMap
```
public static <T,K,U,M extends java.util.Map<K,U>> Collector<T,?,M> toMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 BinaryOperator mergeFunction,
 Supplier<M> mapFactory)
```
 Returns a Collector 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:
 
 keyExtractor - 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, BiFunction)
 
 mapFactory - a function which returns a new, empty Map into which the results will be inserted
 
 Returns:
 
 a Collector 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(Function, Function), toMap(Function, Function, BinaryOperator), toConcurrentMap(Function, Function, BinaryOperator, Supplier)
 - toImmutableMap
```
public static <K,V> Collector<java.util.Map.Entry<K,V>,?,ImmutableMap<K,V>> toImmutableMap()
```
 - toImmutableMap
```
public static <K,V> Collector<java.util.Map.Entry<K,V>,?,ImmutableMap<K,V>> toImmutableMap(BinaryOperator<V> mergeFunction)
```
 - toImmutableMap
```
public static <T,K,U> Collector<T,?,ImmutableMap<K,U>> toImmutableMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper)
```
 - toImmutableMap
```
public static <T,K,U> Collector<T,?,ImmutableMap<K,U>> toImmutableMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 BinaryOperator mergeFunction)
```
 - toLinkedHashMap
```
public static <T,K,U> Collector<T,?,java.util.LinkedHashMap<K,U>> toLinkedHashMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper)
```
 Parameters:
 
 keyExtractor -
 
 valueMapper -
 
 Returns:
 
 See Also:
 
 toMap(Function, Function)
 - toLinkedHashMap
```
public static <T,K,U> Collector<T,?,java.util.LinkedHashMap<K,U>> toLinkedHashMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 BinaryOperator mergeFunction)
```
 Parameters:
 
 keyExtractor -
 
 valueMapper -
 
 mergeFunction -
 
 Returns:
 
 See Also:
 
 toMap(Function, Function, BinaryOperator)
 - toConcurrentMap
```
public static <T,K,U> Collector<T,?,java.util.concurrent.ConcurrentMap<K,U>> toConcurrentMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper)
```
 Returns a concurrent Collector that accumulates elements into a ConcurrentMap 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 toConcurrentMap(Function, Function, BinaryOperator) 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:
 
 keyExtractor - the mapping function to produce keys
 
 valueMapper - the mapping function to produce values
 
 Returns:
 
 a concurrent, unordered Collector which collects elements into a ConcurrentMap 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 the input elements
 
 See Also:
 
 toMap(Function, Function), toConcurrentMap(Function, Function, BinaryOperator), toConcurrentMap(Function, Function, BinaryOperator, Supplier)
 - toConcurrentMap
```
public static <T,K,U,M extends java.util.concurrent.ConcurrentMap<K,U>> Collector<T,?,M> toConcurrentMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 Supplier<M> mapFactory)
```
 - toConcurrentMap
```
public static <T,K,U> Collector<T,?,java.util.concurrent.ConcurrentMap<K,U>> toConcurrentMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 BinaryOperator mergeFunction)
```
 Returns a concurrent Collector that accumulates elements into a ConcurrentMap 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:
 
 keyExtractor - 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, BiFunction)
 
 Returns:
 
 a concurrent, unordered Collector which collects elements into a ConcurrentMap 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:
 
 toConcurrentMap(Function, Function), toConcurrentMap(Function, Function, BinaryOperator, Supplier), toMap(Function, Function, BinaryOperator)
 - toConcurrentMap
```
public static <T,K,U,M extends java.util.concurrent.ConcurrentMap<K,U>> Collector<T,?,M> toConcurrentMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 BinaryOperator mergeFunction,
 Supplier<M> mapFactory)
```
 Returns a concurrent Collector that accumulates elements into a ConcurrentMap 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 ConcurrentMap is created by a provided supplier function.
 This is a concurrent and unordered 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
 
 M - the type of the resulting ConcurrentMap
 
 Parameters:
 
 keyExtractor - 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, BiFunction)
 
 mapFactory - a function which returns a new, empty Map into which the results will be inserted
 
 Returns:
 
 a concurrent, unordered Collector which collects elements into a ConcurrentMap 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:
 
 toConcurrentMap(Function, Function), toConcurrentMap(Function, Function, BinaryOperator), toMap(Function, Function, BinaryOperator, Supplier)
 - toBiMap
```
public static <T,K,U> Collector<T,?,BiMap<K,U>> toBiMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper)
```
 - toBiMap
```
public static <T,K,U> Collector<T,?,BiMap<K,U>> toBiMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 Supplier<BiMap<K,U>> mapFactory)
```
 - toBiMap
```
public static <T,K,U> Collector<T,?,BiMap<K,U>> toBiMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 BinaryOperator mergeFunction)
```
 - toBiMap
```
public static <T,K,U> Collector<T,?,BiMap<K,U>> toBiMap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 BinaryOperator mergeFunction,
 Supplier<BiMap<K,U>> mapFactory)
```
 - toMultimap
```
public static <K,E> Collector<java.util.Map.Entry<? extends K,? extends E>,?,ListMultimap<K,E>> toMultimap()
```
 - toMultimap
```
public static <K,E,V extends java.util.Collection<E>,M extends Multimap<K,E,V>> Collector<java.util.Map.Entry<? extends K,? extends E>,?,M> toMultimap(Supplier<M> mapFactory)
```
 - toMultimap
```
public static <T,K> Collector<T,?,ListMultimap<K,T>> toMultimap(Function<? super T,? extends K> keyExtractor)
```
 - toMultimap
```
public static <T,K,V extends java.util.Collection<T>,M extends Multimap<K,T,V>> Collector<T,?,M> toMultimap(Function<? super T,? extends K> keyExtractor,
 Supplier<M> mapFactory)
```
 - toMultimap
```
public static <T,K,U> Collector<T,?,ListMultimap<K,U>> toMultimap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper)
```
 - toMultimap
```
public static <T,K,U,V extends java.util.Collection,M extends Multimap<K,U,V>> Collector<T,?,M> toMultimap(Function<? super T,? extends K> keyExtractor,
 Function<? super T,? extends U> valueMapper,
 Supplier<M> mapFactory)
```
 - toDataSet
```
public static <T> Collector<T,?,DataSet> toDataSet()
```
 - toDataSet
```
public static <T> Collector<T,?,DataSet> toDataSet(java.util.List<java.lang.String> columnNames)
```

Class Collectors

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Method Detail

toCollection

toList

toLinkedList

toImmutableList

toSet

toLinkedHashSet

toImmutableSet

toQueue

toDeque

toCollection

toList

toSet

toMultiset

toMultiset

toLongMultiset

toLongMultiset

toArray

toArray

toBooleanList

toBooleanArray

toCharList

toCharArray

toByteList

toByteArray

toShortList

toShortArray

toIntList

toIntArray

toLongList

toLongArray

toFloatList

toFloatArray

toDoubleList

toDoubleArray

last

joining

joining

joining

filtering

filtering

mapping

mapping

flatMapping

flatMapping

collectingAndThen

distinctBy

distinctCount

counting

countingInt

min

minBy

minByOrGet

minByOrThrow

max

maxBy

maxByOrGet

maxByOrThrow

pairing

minMax

maxAll

maxAll

maxAll

maxAll

maxAll

minAll

minAll

minAll

minAll

minAll

summingInt

summingInt2

summingLong

summingLong2

summingDouble

summingDouble2