add the missing code: Read a $3-$character string from input into variable userString. Declare a Boolean variable isValid and assign isValid with true if userString does not contain any alphabetic characters. Otherwise, assign isValid with false.

Ex: If the input is $-..,$ then isValid is assigned with true, so the output is:

String is valid

Ex: If the input is $2$p$3,$ then isValid is assigned with false, so the output is:

String is not valid import java.util.Scanner;

public class StringChecker $\{$

public static void main$($String$[]$ args$)\{$

Scanner scnr $=$ new Scanner$($System$.$in$)$;

String userString;

if $($isValid$)\{$

System.out.println$("$String is valid"$)$;

$\}$

else $\{$

System.out.println$("$String is not valid"$)$;

$\}$