Java8 stream map example 2017-08-17 04:16

map function in Stream class means you can pass Function and get another Stream result. It is very useful when you want convert collection to another collection. In this page I'll give you a demonstration how to convert list of User to a list of user's name and age.

public class User {
    private String name;
    private int age;

    public User(String name, int age) { = name;
        this.age = age;
    // getter and setter methods

public class StreamMapClient {
    public static void main(String[] args) {
        List<User> users = new ArrayList<>();
        users.add(new User("henry", 28));
        users.add(new User("justin", 27));
        users.add(new User("Mathew", 26));
        List<Integer> ages =;
        List<String> names =;


[28, 27, 26]
[henry, justin, Mathew]