Java: Check if a number is a double digit or single-digit no if statement?

Question

I have homework to check if number is a double digit or a single-digit without using if statement. Thanks for your help!

public class SchoolTest {
    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);
        int x;
        System.out.println("Please enter a number");
        x = reader.nextInt();
        if ((x > 9 && x < 100) || (x < -9 && x > -100)) {
            System.out.println(true);
            main(args);
        } else {
            System.out.println(false);
            main(args);
        }
    }
}

It's good practice to explain your code a bit when you post a question. :) — JustBlossom, Jun 05 '16 at 15:00

score 12 · Answer 1 · answered Oct 28 '14 at 20:14

12

Just set the value to the conditional:

boolean isDoubleDigit = (x > 9 && x < 100) || (x < -9 && x > -100);
System.out.println( isDoubleDigit );

answered Oct 28 '14 at 20:14

clcto

9,530
20
42

score 3 · Answer 2 · answered Oct 28 '14 at 20:20

If the number is known to be non-negative:

int digits = Integer.toString(theIntValue).trim().length();

(trim() probably isn't needed.)

If it might be negative:

int digits = Integer.toString(Math.abs(theIntValue)).trim().length();

If you must return a boolean:

boolean isTwoDigit = Integer.toString(Math.abs(theIntValue)).trim().length() == 2;

score 2 · Answer 3 · answered Oct 28 '14 at 20:18

2

public class Digits {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int check = scan.nextInt();
        //False for single digit, true for double digit
        boolean isDoubleDigit = (check / 10 == 0 && check / 100 == 0) ? false : true;
        System.out.println(isDoubleDigit);
    }
}

Ternary operator is quite helpful in your case

answered Oct 28 '14 at 20:18

spb1994

114
8

2

Don't really need the ternary operator either, `bool isDoubleDigit = ! ( check / 10 == 0 && check / 100 == 0 )` – clcto Oct 28 '14 at 22:16

score 0 · Answer 4 · answered Oct 28 '14 at 20:13

0

You could read the number in as a String rather than an int and use Regex

answered Oct 28 '14 at 20:13

Gavin

1,725
21
34

Can you show me an example? – user3819756 Oct 28 '14 at 20:14
It might be over kill, clcto has a simpler answer. This tutorial might help: http://tutorials.jenkov.com/java-regex/matcher.html – Gavin Oct 28 '14 at 20:18

score -2 · Answer 5 · answered Feb 02 '18 at 16:52

-2

Should have been written without the main (args)

answered Feb 02 '18 at 16:52

Shane parker

1

2

Put differently; this is not an answer, and is vague and more likely to lead the asker (and anyone who sees this) off-track rather than actually help. – Ironcache Feb 02 '18 at 17:13

Java: Check if a number is a double digit or single-digit no if statement?

5 Answers5