Sort characters in a string

The problem

Write a method that returns a sorted string using the following header: public static String sort(String s). For example, sort("acb") returns abc. Write a test program that prompts the user to enter a string and displays the sorted string.

Breaking it down

public static void main(String[] args) {

    System.out.print("Enter a string: ");
    Scanner input = new Scanner(System.in);
    String s = input.next();
    input.close();

    Stream.of(s.split("")).sorted().forEach(System.out::println);
}

Output

Enter a string: acb
a
b
c