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Thread: check if a number is an integer

  1. #1
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    Default check if a number is an integer

    whats best way to check if a number is an integer?

    Ive heard of doing it this way
            test = Math.floor(num1);
            if(test == num1)
                System.out.println("integer");

    any other ways? (and is there any time where i could run into a problem with this method?)
    Last edited by rsala004; August 15th, 2009 at 05:51 PM.


  2. #2
    mmm.. coffee JavaPF's Avatar
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    Default Re: check if a number is an integer

    Hello rsala004.

    It could also be done like this:

    import java.util.Scanner;
     
    public class Konnor {
     
        public static void main(String[] args){
     
              System.out.println("Enter Integer Value: ");
              Scanner sc = new Scanner(System.in);
     
              try { 
              int myInt = Integer.parseInt(sc.next()); 
              System.out.println("Integer value is: " + myInt); 
              } 
              catch(NumberFormatException e) { 
              System.out.println("You have not entered an Integer!"); 
              }
     
        }
     
    }
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    Super Moderator helloworld922's Avatar
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    Default Re: check if a number is an integer

    if (a == (int) a)

    Where a is any primitive data type byte, short, int, long, float, double, or char. If you want to test larger numbers, use long.

    if (a == (long) a)
    Last edited by helloworld922; August 15th, 2009 at 03:38 PM.

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    Super Moderator Json's Avatar
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    Default Re: check if a number is an integer

        Character.isDigit()

    // Json

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