Java do-while loop isn't working

Question

I want my program to keep asking the question until it gets a response it can use, specifically a number from 0 to 20. I have a lot of other stuff on this class, so here is a small excerpt where the do-while is (I have named the variables and all that for everything).

public static void main(String[] args) {
    do {
        halp = 1;
        System.out.println("What level is your fort?");
        Scanner sc = new Scanner(System.in);

        try { 
            fortLevel = Integer.parseInt(sc.nextLine()); 
        }
        catch(NumberFormatException e){System.out.println("Numbers only, 0-20"); halp = 0;
    }

    if(halp < 1) {
        work = false;
    }

    if(halp > 1) {
        work = true;
    }

    while(work = false);
}

is there any reason to create the scanner inside of the loop? — Kailua Bum
– Kailua Bum, Commented Dec 26, 2012 at 18:51

PermGenError · Accepted Answer · 2012-12-26 18:28:53Z

4

while(work = false); // here you are assigning false to work

should be

while(work == false); //here you are checking if work is equal to false

= an assignment operator used to assign value
== an equality operator used to check if two operands have same value.

As work is boolean you could even just use this:

while(!work)

answered Dec 26, 2012 at 18:28

PermGenError

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Comments

Reimeus · Accepted Answer · 2012-12-26 19:01:12Z

3

You are using an assignment in your while expression:

while(work = false);

You can replace with

while(work == false);

or better

while(!work);

If variables halp and work are not used anywhere else, they could be eliminated giving you:

do {
   System.out.println("What level is your fort?");
   Scanner sc = new Scanner(System.in);
   try {
    fortLevel = Integer.parseInt(sc.nextLine());
   } catch (NumberFormatException e) {
     System.out.println("Numbers only, 0-20");
   }

} while (fortLevel < 0 || fortLevel > 20);

edited Dec 26, 2012 at 19:01

answered Dec 26, 2012 at 18:29

Reimeus

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2 Comments

user1860973 Over a year ago

i've done this, but it still types out the "numbers only, 0-20" and then doesn't allow me to retype sc

Reimeus Over a year ago

You are setting halp to 1 which makes work true so you exit the loop immediately.

Tapas Bose · Accepted Answer · 2012-12-26 19:04:07Z

0

You could also do this:

if(!work) {break;}

answered Dec 26, 2012 at 19:04

Tapas Bose

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