InputMismatchException when reading alphanumeric user input from java.util.Scanner

Question

import java.util.Scanner;

public class StrinExp {
    public static void main(String args[]) {
        Scanner scanner = new Scanner(System.in);
        int i = 0;
        String a = null;
        System.out.println("Enter username");
        i=scanner.nextInt();
        a=a.valueOf(i);
        System.out.print(a);
    }
}

But m getting error when i am giving a alphanumeric value..

ex: Manish0818

and even when i am giving same value as string, still facing the same problem.

Help

That is i am asking, how i can give a alphanumeric input suppose a username like Manis0818 — Manish Kumar, Mar 14 '16 at 12:59

sameera sy · Accepted Answer · 2016-03-14T13:45:01.517

2

change your input statement.

String a = null;
System.out.println("Enter username");
a = scanner.next();
System.out.println(a);

If there's an alphanumeric, then take it in as a string, not as an integer. You will land in an InputMismatchException if you do so. It means that you're trying to take an integer but you are entering a string which differ in data types.

and if you wish to remove all junk characters except alphanumeric then you can try

a = a.replaceAll("[^a-zA-Z0-9]+", "");

edited Mar 14 '16 at 13:45

answered Mar 14 '16 at 12:55

sameera sy

1,708
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19

Well i have already done that previously, do you know how can i do this using regex username with special char – Manish Kumar Mar 14 '16 at 13:07
what do you wanna do actually? Replace all special characters in a string or take only alphanumeric characters as input? – sameera sy Mar 14 '16 at 13:12
suppose i have a line like "manish@34%#" i want to remove, all special char.. How it can be done ? – Manish Kumar Mar 14 '16 at 13:33
check the answer now @ManishKumar – sameera sy Mar 14 '16 at 13:45

InputMismatchException when reading alphanumeric user input from java.util.Scanner

1 Answers1