[SOLVED]Can any one explain it for me??

Question

what does that white space after 9 do?and how it does that?
this is with white space:

import java.util.Scanner;

public class Program
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
String input = sc.nextLine();
input = input.replaceAll("[^a-zA-Z0-9 ]", "");
System.out.println(input);
sc.close();
}
}

and this without that white space:

import java.util.Scanner;

public class Program
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
String input = sc.nextLine();
input = input.replaceAll("[^a-zA-Z0-9]", "");
System.out.println(input);
sc.close();
}
}

Answer 1

"[^a-zA-Z0-9 ]" this regex string mean
(replace) everything
[^] but not
a-zA-Z alphabet characters
0-9 numbers
[^ ] and not space character

String input = "aa-x x-BB-x x-99";
input = input.replaceAll("[^a-zA-Z0-9 ]", ".");
System.out.println(input);

Answer 2

thank you so much 👍