# Uses of Interface
java.util.function.ToIntFunction

Packages that use ToIntFunction
Package
Description
java.util
Contains the collections framework, some internationalization support classes, a service loader, properties, random number generation, string parsing and scanning classes, base64 encoding and decoding, a bit array, and several miscellaneous utility classes.
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 ToIntFunction in java.util

Methods in java.util with parameters of type ToIntFunction
Modifier and Type
Method
Description
`static <T> Comparator<T>`
Comparator.`comparingInt(ToIntFunction<? super T> keyExtractor)`
Accepts a function that extracts an `int` sort key from a type `T`, and returns a `Comparator<T>` that compares by that sort key.
`default Comparator<T>`
Comparator.`thenComparingInt(ToIntFunction<? super T> keyExtractor)`
Returns a lexicographic-order comparator with a function that extracts an `int` sort key.

## Uses of ToIntFunction in java.util.concurrent

Methods in java.util.concurrent with parameters of type ToIntFunction
Modifier and Type
Method
Description
`int`
ConcurrentHashMap.`reduceEntriesToInt(long parallelismThreshold, ToIntFunction<Map.Entry<K,V>> transformer, int basis, IntBinaryOperator reducer)`
Returns the result of accumulating the given transformation of all entries using the given reducer to combine values, and the given basis as an identity value.
`int`
ConcurrentHashMap.`reduceKeysToInt(long parallelismThreshold, ToIntFunction<? super K> transformer, int basis, IntBinaryOperator reducer)`
Returns the result of accumulating the given transformation of all keys using the given reducer to combine values, and the given basis as an identity value.
`int`
ConcurrentHashMap.`reduceValuesToInt(long parallelismThreshold, ToIntFunction<? super V> transformer, int basis, IntBinaryOperator reducer)`
Returns the result of accumulating the given transformation of all values using the given reducer to combine values, and the given basis as an identity value.

## Uses of ToIntFunction in java.util.stream

Methods in java.util.stream with parameters of type ToIntFunction
Modifier and Type
Method
Description
`static <T> Collector<T,?,Double>`
Collectors.`averagingInt(ToIntFunction<? super T> mapper)`
Returns a `Collector` that produces the arithmetic mean of an integer-valued function applied to the input elements.
`IntStream`
Stream.`mapToInt(ToIntFunction<? super T> mapper)`
Returns an `IntStream` consisting of the results of applying the given function to the elements of this stream.
`static <T> Collector<T,?,IntSummaryStatistics>`
Collectors.`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,?,Integer>`
Collectors.`summingInt(ToIntFunction<? super T> mapper)`
Returns a `Collector` that produces the sum of a integer-valued function applied to the input elements.