Which functional interface is used for the map method in the Stream API?

The map method in Java's Stream API uses the functional interface Function<T, R>, where:

• T is the type of the input element of the stream,
• R is the type of the result after transformation.

The map method accepts an object of type Function<T, R>, which defines how to transform each element of the stream.

Example usage:

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import java.util.function.Function;

public class Example {
    public static void main(String[] args) {
        List<String> strings = Arrays.asList("1", "2", "3");
        List<Integer> numbers = strings.stream()
            .map(Integer::parseInt) // Function<String, Integer>
            .collect(Collectors.toList());
        System.out.println(numbers); // [1, 2, 3]
    }
}