Java - while loop for scanner validation results in failed input

Question

I am trying to add the following scanner validation as follows;

public void promptFilmRating() {
    while (!filmScanner.hasNextInt()) {
        System.out.println("Please enter a number instead of text.");
        filmScanner.next();
    }
    while (filmScanner.nextInt() > 5 || filmScanner.nextInt() < 1) {
        System.out.println("Your number is outside of the rating boundaries, enter a number between 1 and 5.");
        filmRatingOutOfFive = filmScanner.nextInt();
    }

}

However when using the code that relates to the integer between value validation, repeated inputs are needed in order to record the original input and I am unsure on how to correct this, any advice would be fantastic.

store it into a variable?

Mansuro
– Mansuro

2018-05-04 21:50:24 +00:00
Commented May 4, 2018 at 21:50 — Mansuro
– Mansuro, Commented May 4, 2018 at 21:50

Dmich · Accepted Answer · 2018-05-04 22:05:04Z

1

I believe your problem is in while (filmScanner.nextInt() > 5 || filmScanner.nextInt() < 1) {. Every call to filmScanner.nextInt() asks the stream for a new integer, so by calling .nextInt() twice in the while statement, you are asking for two numbers.

You might want to consider combining your two loops into one. Example:

int myNum;
do {
    myNumb = filmScanner.nextInt();
} while (myNum > 5 || myNum < 1);

answered May 4, 2018 at 22:05

Dmich

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Comments

RyanJ · Accepted Answer · 2018-05-04 22:12:08Z

1

Store the value that you are getting in a variable, and use that variable to perform the checks.

Here is an example:

private void promptFilmRating() {

    Scanner filmScanner = new Scanner(System.in);
    int filmRatingOutOfFive;

    do{
        System.out.println("Please enter your rating for the film:");
        filmRatingOutOfFive = filmScanner.nextInt();

        if(filmRatingOutOfFive > 5 || filmRatingOutOfFive < 1)
            System.out.println("Your number is outside of the rating boundaries, enter a number between 1 and 5.");

    }while(filmRatingOutOfFive > 5 || filmRatingOutOfFive < 1);


    System.out.println("You rated this film: "+filmRatingOutOfFive+" out of 5");


}

edited May 4, 2018 at 22:12

answered May 4, 2018 at 22:02

RyanJ

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