Simple interest calculator

/**
 * This answers Exercise 3 of Worksheet one, please read and understand the code
 * and check it against resources available online, or ask your tutor as I think
 * that there might be some refinement needed here.
 *
 * @author Shaun B
 * @version 2012-10-30
 **/
import java.util.Scanner;
public class exerciseThree
{
    // Here is our fixed interest rate expressed as a final (ie, cannot be modified):
    private static final double fixedInterestRate = (double)2.3;
    private static int numberOfYears = 0;
    private static Scanner keyboardInput = new Scanner(System.in);
    private static boolean run = true;
    public static void main(String [] elephants)
    {
        // Local variables available in this scope only:
        int i = 0;
        double total = 0.00;
        double capital = 0.00;
        int step = 0;
        double currentBalance = 0.00;
        String keyboardError="Illegal keyboard entry in main class";
        // User instructions:
        System.out.format("The current fixed interest rate is at %f\n",fixedInterestRate);
        System.out.println("This example will ask for an investment capital and add");
        System.out.println("the interest after each year up to 500 years. You will be");
        System.out.println("asked to enter your initial capital amount, how many years");
        System.out.println("of interest and the step in each year(ie, 5 will show you");
        System.out.println("how much interest is added after each five years up to the");
        System.out.println("maximum that you enter).");
        while (run)
        {
            System.out.print("How much capital do you wish to invest? £");
            try
            {
                capital = keyboardInput.nextDouble();
            }
            catch(Exception e)
            {
                System.err.println(keyboardError);
                run = false;
                System.exit(0);
            }
            System.out.print("How many years do you wish to calculate the interest? ");
            try
            {
                numberOfYears = keyboardInput.nextInt();
            }
            catch(Exception e)
            {
                System.err.println(keyboardError);
                run = false;
                System.exit(0);
            }
            System.out.print("How often do you wish to see the balance (ie, every 5 years)? ");
            try
            {
                step = keyboardInput.nextInt();
            }
            catch(Exception e)
            {
                System.err.println(keyboardError);
                run = false;
                System.exit(0);
            }
            if (capital == 0 || numberOfYears == 0 || step == 0)
            {
                System.out.println("Goodbye!");
                run = false;
                System.exit(0);
            }
            for( i=1; i<=numberOfYears; ++i )
            {
                // The exercise seems to be asking for a simple interest calculation,
                // rather than a compound interest calculation, and this is the formula
                // provided on the sheet, so it seems to be okay. I'd check this - search
                // online for a simple interest calculator in Java or C/C++ and you
                // should have a more perfect solution I think.
                currentBalance = (double)capital*(1.00f + 0.01f * fixedInterestRate);
                if(i%step==0 && i!=0)
                {
                    // Prints out the current balance to two decimal places:
                    System.out.printf("After %d years, the balance is %.2f", i, currentBalance);
                    System.out.println("");
                }
                capital = (double)currentBalance;
            }
        }
    }
}