CODEWITHSUNDEEP
javawhile-loopjava.util.scannerdo-whileinputmismatchexception
Jeffrey Soto
Jeffrey Soto

Reputation: 1

InputMismatchException...even with try/catch

So I'm writing code here just for fun but I've come up with an error that I just can't seem to fix. This block of code is supposed to take in an int... at first i had the hasNextInt() in the while loop alone to try and ensure i'm getting the correct input, but as fate would have it.. i got the exception. I then added a try catch to it thinking maybe i just did something wrong... and still i get the same error. I don't know whats wrong here. this is actually my 1st time using a try catch block (still kind of a noob). it looks good to me and i've looked at the documentation online and done some minor research but to no avail. can anyone identify whats wrong here? check it out:

do{
    System.out.println("How much AP do you want to allocate towards HP? ");

    try {//added try catch... still throwing the exception..

        while(!in.hasNextInt()){//this should've been enough, apparently not
            System.out.println("That is not a valid input, try again.");
            in.nextInt();
            }
    } catch (InputMismatchException e) {
        System.out.print(e.getMessage()); //trying to find specific reason.
    }
    hpInput = in.nextInt();
}while(hpInput < 0 || hpInput > AP);

if i entered a string it would give me the "That is not a valid input, try again." line.. but the exception would still occur right after instead of just looping until an actual int is detected... help plz..

Upvotes: 0

Views: 576

Answers (2)

Elliott Frisch
Elliott Frisch

Reputation: 201439

Your while loop should look something like this

while(!in.hasNextInt()){ // <-- is there an int?
    System.out.println("That is not a valid input, try again.");
    // in.nextInt(); // <-- there is not an int...
    in.next(); // <-- this isn't an int.
}

Because the Scanner doesn't have an int.

Upvotes: 2

MadProgrammer
MadProgrammer

Reputation: 347204

You can't really validate the value in the Scanner until something has been input, but once it's input, it's too late to validate it...

Instead, you could use a second Scanner to validate the String result you are getting from the user via the keyboard, for example

Scanner kbd = new Scanner(System.in);
int result = -1;
do {
    System.out.println("How much AP do you want to allocate towards HP? ");
    String value = kbd.nextLine();
    Scanner validate = new Scanner(value);
    if (validate.hasNextInt()) {
        result = validate.nextInt();
    }
} while (result < 0);

Upvotes: 0

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