Exception for java Swing application?
For some reason this is locking up the java application. Did I handle the exception correctly?

  private void submitButtonActionPerformed(java.awt.event.ActionEvent evt) {                                             
        double amount, interest,rateCalc, a, b, c, payment;
        int years, months;
        while (true){
            try{
                amount = Double.valueOf(loanAmount.getText());
                interest = Double.valueOf(interestRate.getText());
                years = Integer.valueOf(loanYears.getText());
                rateCalc = (interest/12);
                months = (years*12);
                a = Math.pow((1+rateCalc),months);
                b = (a*rateCalc);
                c = (a-1);
                payment = (amount *(b/c));
                monthlyPayment.setText("Mortgage Payment $ = " + payment);

            } catch (NumberFormatException nfe){
                javax.swing.JOptionPane.showMessageDialog(null,
                        "Please enter numbers and not letters");
                return;
            }
        }

    }

monthlyPayment returns to the java app.
Exception for java Swing application?
===

For some reason this is locking up the java application. Did I handle the exception correctly?

  private void submitButtonActionPerformed(java.awt.event.ActionEvent evt) {                                             
        double amount, interest,rateCalc, a, b, c, payment;
        int years, months;
        while (true){
            try{
                amount = Double.valueOf(loanAmount.getText());
                interest = Double.valueOf(interestRate.getText());
                years = Integer.valueOf(loanYears.getText());
                rateCalc = (interest/12);
                months = (years*12);
                a = Math.pow((1+rateCalc),months);
                b = (a*rateCalc);
                c = (a-1);
                payment = (amount *(b/c));
                monthlyPayment.setText("Mortgage Payment $ = " + payment);

            } catch (NumberFormatException nfe){
                javax.swing.JOptionPane.showMessageDialog(null,
                        "Please enter numbers and not letters");
                return;
            }
        }

    }

monthlyPayment returns to the java app.