Do-While Loop continuously prints when Program is ran

Question

I have the following code used in my program:

do {
    if (numOfItems == 3 || numOfItems == 5 || numOfItems == 7 || numOfItems == 9) {
        addItems(numOfItems);

    } else {
        System.out.println("That number is out of range.");
        System.out.println("Please choose an odd number in the range of [1, 10] exclusively:");
        numOfItems = scan.nextInt();
    }
} while (numOfItems != 3 || numOfItems != 5 || numOfItems != 7 || numOfItems != 9);

which, when run, keeps repeating the method which I only want to happen once. How to I make the loop keep repeating for validation, but only run the method once?

VHS · Accepted Answer · 2017-01-15 04:16:34Z

3

Replace

while (numOfItems != 3 || numOfItems != 5 || numOfItems != 7 || numOfItems != 9);

with

while (numOfItems != 3 && numOfItems != 5 && numOfItems != 7 && numOfItems != 9);

Update

From your comment to the answer, it looks like you need to do something like following:

do {
    numOfItems = scan.nextInt();
    if (numOfItems == 3 || numOfItems == 5 || numOfItems == 7 || numOfItems == 9) {
        addItems(numOfItems);

    } else {
        System.out.println("That number is out of range.");
        System.out.println("Please choose an odd number in the range of [1, 10] exclusively:");

    }
} while (numOfItems != 3 && numOfItems != 5 && numOfItems != 7 && numOfItems != 9);

However, you can optimize this to something like following:

while ((numOfItems = scan.nextInt() != 3) && numOfItems != 5 && numOfItems != 7 && numOfItems != 9) {

            System.out.println("That number is out of range.");
            System.out.println("Please choose an odd number in the range of [1, 10] exclusively:");
}

addItems(numOfItems);

edited Jan 15, 2017 at 4:16

answered Jan 15, 2017 at 4:08

VHS

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5 Comments

Kooba Over a year ago

That fixes the solution, however, now it doesn't validate correctly. If I enter in a number not 3, 5, 7, or 9 then enter one of those numbers, the method doesn't run?

VHS Over a year ago

Isn't that a desirable behavior? Keep on running the loop until the user enters one of those 4 numbers? If this is not the desired behavior, you need to provide more explanation

David Choweller Over a year ago

@Kooba: What do you mean by "the method." The code excerpt you provided does not call any method.

Kooba Over a year ago

@VHS Your first solution fixed my problem. Not sure how exactly but it works optimally now, thanks!

VHS Over a year ago

@Kooba, glad that I could be of help.

Naman · Accepted Answer · 2017-01-15 04:09:00Z

1

You might want to correct

while (numOfItems != 3 || numOfItems != 5 || numOfItems != 7 || numOfItems != 9);

since, it would always be true.

You can get rid of this(do..while) condition if you always want to execute the do{...} block of statements. ("...which I only want to happen once")

answered Jan 15, 2017 at 4:09

Naman

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