title: Exception for java Swing application?
body: <p>For some reason this is locking up the java application. Did I handle the exception correctly?</p>
  
  <pre><code>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;
          }
      }
  
  }
  </code></pre>
  
  <p>monthlyPayment returns to the java app.</p>