import java.text.NumberFormat;
import javax.swing.JOptionPane;
 
/**

 */
 
public class Program3st
{
  public static void main(String[] args)
  {      // begin defined variables and Strings (1)
  double subTotal = 0;
  double salestax = .0785;
  String choice = " ";
  String inputString = " ";
             // End variables and Strings (1)
 
  try
               // start try block (1)
  {
  while (!(inputString.equalsIgnoreCase("x")))
                  // begin while loop (1) for continued user entry
  {
  inputString = JOptionPane.showInputDialog(null,
                                              "Enter Subtotal: ",
                                              "",
                                             JOptionPane.QUESTION_MESSAGE);
        subTotal = parseSubTotal(inputString);
          NumberFormat sub = NumberFormat.getCurrencyInstance();
            NumberFormat per = NumberFormat.getCurrencyInstance();
               NumberFormat gran = NumberFormat.getCurrencyInstance();
                 per.setMaximumFractionDigits(2);
                    gran.setMaximumFractionDigits(2);
      inputString = JOptionPane.showInputDialog(null, "SubTotal:   \t" +
                                        sub.format(subTotal) +
                                        "\nTax:   \t" +
                                        per.format(subTotal * salestax) +
                                        "\nGrand Total:  \t" +
                                        gran.format(subTotal * salestax + subTotal) +
                                        "\nPress Enter to continue or 'x' to exit.",
                                        "",
                                        JOptionPane.
                                        INFORMATION_MESSAGE);
   } // end while loop (1)
 
}        // end try block (1)
 
catch (NullPointerException e)
            // begin catch (NP)exception block (1)
{
       System.exit(0);
 
  }            // end catch exception block (1)
 
       System.exit(0);
}
private static double parseSubTotal(String validString)
                    // begin private static method for data validation
{
                       // begin defined variables (2)
double subTotal = 0;
boolean retry = true;
                     // end variables (2)
while(retry)
                        // begin while loop (2) for re-entry
{
try
                           // start try block (2)
{
     subTotal = Double.parseDouble(validString);
           retry = false;
}                             // end try block (2)
 
catch (NumberFormatException e)
                                // begin catch block for (NF)exception
{
       validString = JOptionPane.showInputDialog(null, "Invalid Entry:  \t" +
                                                        validString +
                                                        "\n" +
                                                        "Please Enter A Number:",
                                                        "",
                                                        JOptionPane.ERROR_MESSAGE);
}              // end catch block for (NF)exception
catch (NullPointerException e)
                     // begin catch block for (NP)exception (2)
{
    System.exit(0);
    }                     // end catch block for (NP)exception (2)
}
return subTotal;
  }
}