Read a $3-$character string from input into variable userString. Declare a Boolean variable allDigits and assign allDigits with true if userString only contains digits. Otherwise, assign allidigits with false.

Ex: If the input is $875,$ then allDigits is assigned with true, so the output is:

String is valid

Ex: If the input is $m36,$ then allDigits is assigned with false, so the output is:

string is not valid

Note: Use userstring $=$ scnr$.$nextLine $()$ to read the entire line from input into userString.

import Java.util. Scanner;

public class StringChecker $\{$

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

Scanner scnr $=$ new Scanner$($

System.in$)$;

String userstring;

$V**$ Your code goes here $*$

if $($allDigits$)\{$

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

$\}$

else $\{$

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

$\}$

$\}$

$\}$