Throw and catches

[cdawg_2010]

I wrote this program for converting feet and inches entered in to centimeters, but i need help with the catch part. the assignment says that if a user enters a negative or non-digit number, the user should be prompted to enter another number. I think i've just been working on this for too long and i'm overlooking a simple mistake.

   import java.util.Scanner;
   public class Assignment21a {
   
   
      public static void main(String[] args) {
      
         System.out.println(
            "To exit please type any non-number.");
      
         while (true)
         {
            Scanner input = new Scanner(System.in);
            System.out.print("Please enter feet then inches to be converted: ");
            try {
               int feet = input.nextInt();
               int inches = input.nextInt();
               double conversion = 2.54;
            
               int totalInches = ( feet * 12);
               double totalCentimeters = (double) ((totalInches + inches) * conversion);
                 
               System.out.println( totalCentimeters + " centimeters");
            }
               catch (Exception e)
               {
                  System.out.println("Thanks for using the centimeter converter.");
                  break;
               }
         }
      }
   }

[KevinWorkman]

Why bother with the catch to accomplish your goal? What exception would be thrown for a negative number?

Hint: What do you want to do while the user enters negative numbers?

[cdawg_2010]

well our instructor wants us to throw it and suggested using a catch too so thats why i had that in there. its part of the assignment. but i'll think about what you said when looking at it

[KevinWorkman]

Well, in that case: Lesson: Exceptions (The Java™ Tutorials > Essential Classes)