Best example of Singleton

class User {

    private static final User INSTANCE;

    private User() {}

    public static User getInstance() {

        synchronized(User.INSTANCE) {

            if (User.INSTANCE == null) {

                User.INSTANCE = new User();

            }

        }

        return User.INSTANCE;

    }

    public String getName() {

        // return user's name

    }

}

sourc: https://dzone.com/articles/five-features-to-make-java-even-better?utm_source=Top%205&utm_medium=email&utm_campaign=Top%205%202017-11-103