Question

you created an application named QuartsToGallonsInteractive that accepts a number of quarts from a user and converts the value to gallons. Now, add exception-handling capabilities to this program and continuously reprompt the user while any nonnumeric value is entered.

// QuartsToGallonsInteractive.java
import java.util.Scanner;
class QuartsToGallonsInteractive
{
   public static void main(String[] args)
   {
      final int QUARTS_IN_GALLON = 4;
      int quartsNeeded = 18;
      int gallonsNeeded;
      int extraQuartsNeeded;
      Scanner input = new Scanner(System.in);
      System.out.print("Enter quarts needed >> ");
      quartsNeeded = input.nextInt();
      gallonsNeeded = quartsNeeded / QUARTS_IN_GALLON;
      extraQuartsNeeded = quartsNeeded % QUARTS_IN_GALLON;
      System.out.println("A job that needs " + quartsNeeded +
         " quarts requires " + gallonsNeeded + " gallons plus " +
         extraQuartsNeeded + " quarts.");
   }
}

Answer 1

// QuartsToGallonsInteractive.java
import java.util.Scanner;
class QuartsToGallonsInteractive1
{
    public static void main(String[] args)
    {
        final int QUARTS_IN_GALLON = 4;
        int quartsNeeded = 18;
        int gallonsNeeded;
        int extraQuartsNeeded;
        Scanner input = new Scanner(System.in);
        boolean valid = false;
        String s;
        while (!valid) {
            try {
                System.out.print("Enter quarts needed >> ");
                s = input.nextLine();
                quartsNeeded = Integer.parseInt(s);
                valid = true;
            } catch (Exception e) {
                System.out.println("Invalid input");
            }
        }
        gallonsNeeded = quartsNeeded / QUARTS_IN_GALLON;
        extraQuartsNeeded = quartsNeeded % QUARTS_IN_GALLON;
        System.out.println("A job that needs " + quartsNeeded +
                " quarts requires " + gallonsNeeded + " gallons plus " +
                extraQuartsNeeded + " quarts.");
    }
}