What is the Stream map() method in Java?
Overview
The Stream map() method is used to transform elements of a stream by applying a mapping function to each element. The mapped stream is then returned as a new stream.
This method accepts a Function mapper object as an argument. This function describes how each element in the original stream is transformed into an element in the new stream.
Syntax
Stream map(Function mapper)
Syntax of Stream map() method
Parameters
mapper: This is a non-interfering, stateless function to apply to each element.
Return value
It returns the new stream consisting of the results of applying the given function to the elements of this stream.
Example
import java.util.*;import java.util.stream.*;public class Main {public static void main(String[] args) {Integer[] nums = {1, 2, 3, 4};Stream<Integer> map = Arrays.stream(nums).map(n -> n * 2);map.forEach(System.out::println);}}
Explanation
- Line 7: We use the
Arrays.stream()method to convert the integer arraynumsinto a stream. This stream is mapped using themap()method. We pass a lambda function that multiplies each integer value by2. - Line 9: We use the
forEach()method to print out each element of the stream.