Checking for digits

Question

I'm trying to figure out this problem. The directions are set hasDigit to true when a three character passCode from a scanner contains a digit.

Code below

import java.util.Scanner;

public class CheckingPasscodes {
   public static void main (String [] args) {
      Scanner scnr = new Scanner(System.in);
      boolean hasDigit;
      String passCode;

      hasDigit = false;
      passCode = scnr.next();

      hasDigit = Character.isDigit(passCode);
     
      
      

      if (hasDigit) {
         System.out.println("Has a digit.");
      }
      else {
         System.out.println("Has no digit.");
      }
   }
}

I've entered in the line hasDigit = Character.isDigit(passCode);

My logic is that character.isDigit is checking the passCode from the scanner, but I keep getting an error.

I've also tried: hasDigit = Character.isDigit(0); and the first test passes, but not the other. From this I assumed that I would have to enter in the string so it would test for anything, not just the character at position 0.

Thanks for the help.

first step is to look at the javadocs https://docs.oracle.com/javase/7/docs/api/java/lang/Character.html#isDigit(char) — Scary Wombat, Feb 26 '19 at 05:33
...yes...and match that up with javadocs https://docs.oracle.com/javase/8/docs/api/java/util/Scanner.html (look at the definition of the next() method) — CryptoFool, Feb 26 '19 at 05:35
Possible duplicate of [Java String - See if a string contains only numbers and not letters](https://stackoverflow.com/questions/10575624/java-string-see-if-a-string-contains-only-numbers-and-not-letters) — Ammar Ali, Feb 26 '19 at 05:54

score 1 · Answer 1 · answered Jan 21 '23 at 17:59

import java.util.Scanner;

public class CheckingPasscodes {
   public static void main (String [] args) {
      Scanner scnr = new Scanner(System.in);
      boolean hasDigit;
      String passCode;

      hasDigit = false;
      passCode = scnr.next();

      if ((Character.isDigit(passCode.charAt(0))) || (Character.isDigit(passCode.charAt(1))) || (Character.isDigit(passCode.charAt(2)))) {
         hasDigit = true;
      }

      if (hasDigit) {
         System.out.println("Has a digit.");
      }
      else {
         System.out.println("Has no digit.");
      }
   }
}

score 0 · Answer 2 · edited Feb 26 '19 at 06:00

0

for(int i = 0 ;i <passCode.length();i++) {
         hasDigit = Character.isDigit(passCode.charAt(i));
         if (hasDigit) {
             System.out.println("Has a digit.");
             break;
         }
}
if(!hasDigit) {
    System.out.println("Has no digit.");
}

Pity that the answer was revealed but if you are going to spoil the learning process at least try giving the right code :/

edited Feb 26 '19 at 06:00

Scary Wombat

44,617
6
35
64

answered Feb 26 '19 at 05:56

damagedCoda

83
6

Pity that you could not format your code, also I would print only in one place – Scary Wombat Feb 26 '19 at 06:01

prachi · Answer 3 · 2019-02-26T06:06:18.097

-2

isDigit() function of Character class excepts either one character or an integer. It does not excepts string , that's why you are getting error. You can modify your code to -

         hasDigit = false;
          passCode = scnr.next();

         for(int i = 0 ;i <passCode.length();i++) {
             hasDigit = Character.isDigit(passCode.charAt(i));
             if(hasDigit)
               break;
         }
          if (hasDigit) {
             System.out.println("Has a digit.");
          }
          else {
             System.out.println("Has no digit.");
          }

this will give you required result.

edited Feb 26 '19 at 06:06

answered Feb 26 '19 at 05:37

prachi

305
1
7

1

we were trying to help the guy figure this out himself :( – CryptoFool Feb 26 '19 at 05:39
1

this code will store the last value of `Character.isDigit` into `hasDigit` – Scary Wombat Feb 26 '19 at 05:40
So basically this is cycling through each space until it reaches the end of the passcode? – iggylombardi Mar 01 '19 at 01:01

Checking for digits

3 Answers3