Java Makes infinity do while loop :/

Question

I have programmed all night long and I can't find a mistake anymore :/ :/ If intro == 1 or 2 then do this and that.. and if intro != 1 or 2 then ask number again, till the number is 1 or 2... I can't find the mistake :/

   do{
        System.out.println("Enter number: ");
        Scanner scanintro = new Scanner(System.in);
        intro = scanintro.next();
    }while (intro == ("1")|| intro == ("2"));

Your condition is inverted anyway: `while (!intro.equals("1") && !intro.equals("2"));` — Andy Turner, Apr 30 '17 at 11:32

score 5 · Answer 1 · answered Apr 30 '17 at 11:29

5

do{
    System.out.println("Enter number: ");
    Scanner scanintro = new Scanner(System.in);
    intro = scanintro.nextInt();
} while (intro == 1|| intro == 2);

answered Apr 30 '17 at 11:29

Yashar Panahi

2,816
1
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Bas · Answer 2 · 2017-04-30T11:47:01.770

1

do {
    System.out.println("Enter number: ");
    Scanner scanintro = new Scanner(System.in);
    intro = scanintro.next();
} while (!intro.equals("1") && !intro.equals("2"));

You should use equals to compare strings, but its an int(I don't know what the datatype of your intro variable is, but you should change it to an int) so you can check it like this:

do {
    System.out.println("Enter number: ");
    Scanner scanintro = new Scanner(System.in);
    intro = scanintro.next();
} while (intro != 1 || intro != 2);

edited Apr 30 '17 at 11:47

answered Apr 30 '17 at 11:30

Bas

4,423
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36
53

According to the spec in the question, that condition should be inverted: keep going until that value is either 1 or 2. – Andy Turner Apr 30 '17 at 11:35
1

@YCF_L it doesn't actually: what if you enter a non-integer? Then the loop would error out. – Andy Turner Apr 30 '17 at 11:37
yes @AndyTurner this is correct my mistake – Youcef LAIDANI Apr 30 '17 at 11:45
`!intro.equals("1") || !intro.equals("2")`, which you have currently, is always true. – Alexey Romanov Apr 30 '17 at 11:46
@AlexeyRomanov correct, changed it! – Bas Apr 30 '17 at 11:48

Java Makes infinity do while loop :/

2 Answers2