How to handle wrong user input

Question

My program requires user to enter a 4-digit number(int type). Currently, when the user enters any character other than numeric, the program crashes. My hope is that when the user enters a non-numeric character, the program can tell the user "Wrong input" then let the user re-enter.

Does exception handling work for this? Or is there any other good way to solve this?

Your application is already throwing an error when it's crashing. what you need to do is catch the exception, and handle it (print appropriate message to user etc.) — Martin Konecny, May 27 '14 at 02:33
see http://docs.oracle.com/javase/tutorial/essential/exceptions/index.html — vandale, May 27 '14 at 02:34

score 0 · Accepted Answer · edited May 23 '17 at 11:58

If you are using scanner, you can use the nextInt() method with the condition hasNextInt() which would only read integer inputs. Have a look at this post for example:

Taken from the above mentioned post.

Scanner sc = new Scanner(System.in);
System.out.print("Enter number 1: ");
while (!sc.hasNextInt()) sc.next();
int num1 = sc.nextInt();
int num2;
System.out.print("Enter number 2: ");
do {
    while (!sc.hasNextInt()) sc.next();
    num2 = sc.nextInt();
} while (num2 < num1);
System.out.println(num1 + " " + num2);

Also you can look at the documentation for scanner's nextInt() here

How to handle wrong user input

1 Answers1