## Uses of Interface
java.util.concurrent.ConcurrentMap

- Packages that use ConcurrentMap
  Package | Description
  --- | ---
  java.util.concurrent | Utility classes commonly useful in concurrent programming.
  java.util.stream | Classes to support functional-style operations on streams of elements, such as map-reduce transformations on collections.

- - ### Uses of ConcurrentMap in java.util.concurrent

    Subinterfaces of ConcurrentMap in java.util.concurrent
    Modifier and Type | Interface and Description
    --- | ---
    `interface` | `ConcurrentNavigableMap<K,V>` A `ConcurrentMap` supporting `NavigableMap` operations, and recursively so for its navigable sub-maps.

    Classes in java.util.concurrent that implement ConcurrentMap
    Modifier and Type | Class and Description
    --- | ---
    `class` | `ConcurrentHashMap<K,V>` A hash table supporting full concurrency of retrievals and high expected concurrency for updates.
    `class` | `ConcurrentSkipListMap<K,V>` A scalable concurrent `ConcurrentNavigableMap` implementation.

  - ### Uses of ConcurrentMap in java.util.stream

    Methods in java.util.stream with type parameters of type ConcurrentMap
    Modifier and Type | Method and Description
    --- | ---
    `static <T,K,A,D,M extends ConcurrentMap<K,D>> Collector<T,?,M>` | Collectors.`groupingByConcurrent(Function<? super T,? extends K> classifier, Supplier<M> mapFactory, 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,U,M extends ConcurrentMap<K,U>> Collector<T,?,M>` | Collectors.`toConcurrentMap(Function<? super T,? extends K> keyMapper, Function<? super T,? extends U> valueMapper, BinaryOperator<U> mergeFunction, Supplier<M> mapSupplier)` 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.

    Methods in java.util.stream that return types with arguments of type ConcurrentMap
    Modifier and Type | Method and Description
    --- | ---
    `static <T,K> Collector<T,?,ConcurrentMap<K,List<T>>>` | Collectors.`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,?,ConcurrentMap<K,D>>` | Collectors.`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,U> Collector<T,?,ConcurrentMap<K,U>>` | Collectors.`toConcurrentMap(Function<? super T,? extends K> keyMapper, 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,?,ConcurrentMap<K,U>>` | Collectors.`toConcurrentMap(Function<? super T,? extends K> keyMapper, 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.

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