## Uses of Interface
java.util.function.Function

- Packages that use Function
  Package | Description
  --- | ---
  java.util |
  java.util.function |

- - ### Uses of Function in java.util

    Methods in java.util with parameters of type Function
    Modifier and Type | Method and Description
    --- | ---
    `static <T,U extends Comparable<? super U>> Comparator<T>` | Comparator.`comparing(Function<? super T,? extends U> keyExtractor)` Accepts a function that extracts a `Comparable` sort key from a type `T`, and returns a `Comparator<T>` that compares by that sort key.
    `static <T,U> Comparator<T>` | Comparator.`comparing(Function<? super T,? extends U> keyExtractor, Comparator<? super U> keyComparator)` Accepts a function that extracts a sort key from a type `T`, and returns a `Comparator<T>` that compares by that sort key using the specified `Comparator`.
    `default V` | Map.`computeIfAbsent(K key, Function<? super K,? extends V> mappingFunction)` If the specified key is not already associated with a value (or is mapped to `null`), attempts to compute its value using the given mapping function and enters it into this map unless `null`.
    `default <U extends Comparable<? super U>> Comparator<T>` | Comparator.`thenComparing(Function<? super T,? extends U> keyExtractor)` Returns a lexicographic-order comparator with a function that extracts a `Comparable` sort key.
    `default <U> Comparator<T>` | Comparator.`thenComparing(Function<? super T,? extends U> keyExtractor, Comparator<? super U> keyComparator)` Returns a lexicographic-order comparator with a function that extracts a key to be compared with the given `Comparator`.

  - ### Uses of Function in java.util.function

    Subinterfaces of Function in java.util.function
    Modifier and Type | Interface and Description
    --- | ---
    `interface` | `UnaryOperator<T>` Represents an operation on a single operand that produces a result of the same type as its operand.

    Methods in java.util.function that return Function
    Modifier and Type | Method and Description
    --- | ---
    `default <V> Function<T,V>` | Function.`andThen(Function<? super R,? extends V> after)` Returns a composed function that first applies this function to its input, and then applies the `after` function to the result.
    `default <V> Function<V,R>` | Function.`compose(Function<? super V,? extends T> before)` Returns a composed function that first applies the `before` function to its input, and then applies this function to the result.
    `static <T> Function<T,T>` | Function.`identity()` Returns a function that always returns its input argument.

    Methods in java.util.function with parameters of type Function
    Modifier and Type | Method and Description
    --- | ---
    `default <V> Function<T,V>` | Function.`andThen(Function<? super R,? extends V> after)` Returns a composed function that first applies this function to its input, and then applies the `after` function to the result.
    `default <V> BiFunction<T,U,V>` | BiFunction.`andThen(Function<? super R,? extends V> after)` Returns a composed function that first applies this function to its input, and then applies the `after` function to the result.
    `default <V> Function<V,R>` | Function.`compose(Function<? super V,? extends T> before)` Returns a composed function that first applies the `before` function to its input, and then applies this function to the result.

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