The mapToInt() method of the Stream interface is used to return an IntStream that contains the results of applying the provided implementation of the ToIntFunction() function on the stream’s items.
IntStream mapToInt(ToIntFunction<? super T> mapper)
ToIntFunction<? super T> mapper: This is the mapper function that needs to be applied.This method returns a new stream.
import java.util.Arrays;import java.util.List;import java.util.function.ToIntFunction;public class Main{public static void main(String[] args) {// define the list of integersList<Integer> integerList = Arrays.asList(10, 24, 54, 8,232);// Define the implementation of ToIntFunction interfaceToIntFunction<Integer> multiplyByTwo = e -> e * 2;// apply the multiplyByTwo using mapToInt function and print each valueintegerList.stream().mapToInt(multiplyByTwo).forEach(System.out::println);}}