What is the Stream.mapToInt() method in Java?

Overview

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.

Syntax

IntStream mapToInt(ToIntFunction<? super T> mapper)

Parameters

  • ToIntFunction<? super T> mapper: This is the mapper function that needs to be applied.

Return value

This method returns a new stream.

Code

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 integers
        List<Integer> integerList = Arrays.asList(10, 24, 54, 8,232);
        // Define the implementation of ToIntFunction interface
        ToIntFunction<Integer> multiplyByTwo = e -> e * 2;
        // apply the multiplyByTwo using mapToInt function and print each value
        integerList.stream().mapToInt(multiplyByTwo).forEach(System.out::println);
    }
}

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