i have two versions trying to get either one to work. both doing the same thing. getting a square in the answer box. the second version i need help to get the amort to work

First version
import java.io.*;
import java.text.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class MortgageCalc extends JFrame implements ActionListener
{
      //declare variables
      double rateMo, rateApr, monthPmt, principal, iMonths, iYears;

      //create JLabels for entry
      JLabel Dprincipal = new JLabel("Please enter Principal:      ");
      JLabel RateApr = new JLabel("Please enter APR:      ");
      JLabel Years =      new JLabel("Please enter Term:      ");
      JLabel MonthPmt = new JLabel("Your Monthly Payment will be:      ");

      JTextField loanPrincipal = new JTextField("", 10);
      JTextField loanRate = new JTextField("", 10);
      JTextField loanTerm = new JTextField("", 10);
      JTextField loanPayment = new JTextField("", 10);

      //create buttons
      JButton CalcPayment = new JButton("Calculate Payment");
      JButton exit = new JButton("Exit");
      JButton reset = new JButton("Reset");

      public MortgageCalc()
      {
            //Create Frame
            Container container = getContentPane();
            container.setLayout(new BorderLayout(10,10));

            JPanel inputPanel = new JPanel();
            inputPanel.setLayout(new GridLayout(6,4));

            JPanel buttonPanel = new JPanel();
            buttonPanel.setLayout(new GridLayout(8,2));

            JPanel answerPanel = new JPanel();
            answerPanel.setLayout(new FlowLayout());

            //add components to input panel
            inputPanel.add(Dprincipal);
            inputPanel.add(loanPrincipal);
            inputPanel.add(RateApr);
            inputPanel.add(loanRate);
            inputPanel.add(Years);
            inputPanel.add(loanTerm);

            //add components to button panel
            buttonPanel.add(CalcPayment);
            buttonPanel.add(reset);
            buttonPanel.add(exit);

            //add componets to answer
            answerPanel.add(MonthPmt);
            answerPanel.add(loanPayment);

            container.add(inputPanel, BorderLayout.WEST);
            container.add(buttonPanel, BorderLayout.EAST);
            container.add(answerPanel, BorderLayout.SOUTH);

            //add listeners
            CalcPayment.addActionListener(this);
            reset.addActionListener(this);
            exit.addActionListener(this);
            loanPayment.setEditable(false);

      }//End MortgageCalc



      public void actionPerformed(ActionEvent e)
      {
            Object source = e.getSource();
            if(source == CalcPayment)
            {
                  String tPrincipal = loanPrincipal.getText();
                  String rateAPR = loanRate.getText();
                  String years = loanTerm.getText();

                  try
                  {
                        double Dprincipal = Double.parseDouble(tPrincipal);
                        if (Dprincipal <= 0.00) throw new NumberFormatException();
                        double rateApr = Double.parseDouble(rateAPR);
                        if (rateApr <= 0.00) throw new NumberFormatException();
                        double iYears = Double.parseDouble(years);
                        if (iYears <= 0.0) throw new NumberFormatException();
                  }

                  catch(NumberFormatException f)
                  {
                        JOptionPane.showMessageDialog(null, "Invalid Entry, Please Try Again.", "Error", JOptionPane.INFORMATION_MESSAGE);
                  }

                  // calculations
                  rateMo = (rateApr /12)/100;
                  iMonths = (iYears * 12);

                  monthPmt = (principal * rateMo) / (1- Math.pow(1 + rateMo, - iMonths));
                  DecimalFormat twoDigits = new DecimalFormat("$#,###.00");

                  loanPayment.setText(twoDigits.format(monthPmt));
            }

            else if (source == reset)
            {
                  loanPrincipal.setText("");
                  loanRate.setText("");
                  loanTerm.setText("");
                  loanPayment.setText("");
                  loanPrincipal.requestFocus();
            }

            else
            {
                  System.exit(0);
            }
      }//end

      public static void  main(String[] args) throws IOException
      {
            MortgageCalc frame = new MortgageCalc();
            frame.setTitle("Mortgage Payment Calculator V2.0");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setSize(1200,800);
            frame.setVisible(true);
      }//end Main

      public double getResult()
      {
            return monthPmt;
      }


}//end program


second version
import java.io.*;
import java.text.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Mortgage extends JFrame implements ActionListener
{
            // declare some variables
            double dRateMo, dRateAPR, dMonthPmt, dPrincipal, iMonths, iYears;

            // create JLabels for entry fields
            JLabel greeting = new JLabel("Good Day! Please enter your name.");
            JLabel Principal = new JLabel("Please enter principal:    ");
            JLabel rateAPR = new JLabel("Please enter loan rate:      ");
            JLabel years = new JLabel("Please enter term:      ");
            JLabel payment = new JLabel("Your monthly payment will be:  ");

            // create textfields for user entries
            JTextField nameField = new JTextField("", 10);
            JTextField loanPrincipal = new JTextField("", 10);
            JTextField loanRate = new JTextField("", 10);
            JTextField loanTerm = new JTextField("", 10);
            JTextField loanPayment = new JTextField("", 20);

            //create buttons for use in panels
            JButton calcPayment = new JButton("Calculate Payment");
            JButton calcAmort = new JButton("Show Amortization Table");
            JButton nameEntry = new JButton("Enter Name");
            JButton exit = new JButton("Exit");
            JButton reset = new JButton("Reset");

      public Mortgage()
      {
            // create frame and panels
            Container container = getContentPane();
            container.setLayout(new BorderLayout(5,5));

            JPanel inputPanel = new JPanel();
            inputPanel.setLayout(new GridLayout(3,2));

            JPanel buttonPanel = new JPanel();
            buttonPanel.setLayout(new GridLayout(4,1));

            JPanel greetingPanel = new JPanel();
            greetingPanel.setLayout(new FlowLayout());

            JPanel answerPanel = new JPanel();
            answerPanel.setLayout(new FlowLayout());

            // add compenents to greeting panel
            greetingPanel.add(greeting);
            greetingPanel.add(nameField);
            greetingPanel.add(nameEntry);

            //add components to input panel
            inputPanel.add(Principal);
            inputPanel.add(loanPrincipal);
            inputPanel.add(rateAPR);
            inputPanel.add(loanRate);
            inputPanel.add(years);
            inputPanel.add(loanTerm);

            //add components to button panel
            buttonPanel.add(calcPayment);
            buttonPanel.add(calcAmort);
            buttonPanel.add(reset);
            buttonPanel.add(exit);

            //add components to answer panel
            answerPanel.add(payment);
            answerPanel.add(loanPayment);

            //add panels to frame
            container.add(greetingPanel, BorderLayout.NORTH);
            container.add(inputPanel, BorderLayout.WEST);
            container.add(buttonPanel, BorderLayout.EAST);
            container.add(answerPanel, BorderLayout.SOUTH);

            // add listeners to buttons
            calcPayment.addActionListener(this);
            calcAmort.addActionListener(this);
            reset.addActionListener(this);
            exit.addActionListener(this);
            nameEntry.addActionListener(this);
            loanPayment.setEditable(false);
      }

      public void actionPerformed(ActionEvent e)
      {
            Object source = e.getSource();
            if (source == nameEntry)
            {
                  String name = nameField.getText();
                  remove(nameField);
                  remove(nameEntry);
                  validate();
                  greeting.setText("Welcome, " + name + " !");

            }

            else if (source == calcPayment)
            {
                  String totPrincipal = loanPrincipal.getText();
                  String rateAPR = loanRate.getText();
                  String years = loanTerm.getText();

                  try
                  {
                        double dPrincipal = Double.parseDouble(totPrincipal);
                        if (dPrincipal <= 0.00) throw new NumberFormatException();
                        double dRateAPR = Double.parseDouble(rateAPR);
                        if (dRateAPR <= 0.00) throw new NumberFormatException();
                        double iYears = Double.parseDouble(years);
                        if (iYears <= 0.0) throw new NumberFormatException();

                  }

                  catch(NumberFormatException f)
                  {
                        JOptionPane.showMessageDialog(null, "Invalid Entry, please try again.", "Error", JOptionPane.INFORMATION_MESSAGE);
                  }

                  // declare conversion for APR to monthly rate and years to months

                  iMonths = iYears * 12;
                  dRateMo = dRateAPR / (12*100);

                  dMonthPmt = getPayment(dRateMo, iMonths, dPrincipal);
                  DecimalFormat twoDigits = new DecimalFormat("$###,000.00");

                  loanPayment.setText(twoDigits.format(dMonthPmt));
            }

            else if (source == calcAmort)
            {

                  JOptionPane.showMessageDialog(null, "Under Construction", "Error", JOptionPane.INFORMATION_MESSAGE);
                  /*String Principal = loanPrincipal.getText();
                  String rateAPR = loanRate.getText();
                  String years = loanTerm.getText();

                  try
                  {
                        double dPrincipal = Double.parseDouble(Principal);
                        if (dPrincipal <= 0.00) throw new NumberFormatException();
                        double dRateAPR = Double.parseDouble(rateAPR);
                        if (dRateAPR <= 0.00) throw new NumberFormatException();
                        double iYears = Double.parseDouble(years);
                        if (iYears <= 0.0) throw new NumberFormatException();

                  // declare conversion for APR to monthly rate and years to months
                        iMonths = iYears * 12;
                        dRateMo = dRateAPR / (12*100);
                        dMonthPmt = getPayment(dRateMo, iMonths, dPrincipal);
                        PaymentCalc.Calculation(dPrincipal, dRateMo, dMonthPmt, iMonths);
                        if (dPrincipal <= 0.0 || dRateMo <= 0.0 || dMonthPmt <= 0.0 || iMonths <= 0)
                        throw new NumberFormatException();

                  }

                  catch(NumberFormatException f)
                  {
                        JOptionPane.showMessageDialog(null, "Invalid Entry, please try again.", "Error", JOptionPane.INFORMATION_MESSAGE);
                  }
                  */

            }

            else if (source == reset)
            {
                  loanPrincipal.setText("");
                  loanRate.setText("");
                  loanTerm.setText("");
                  loanPayment.setText("");
                  loanPrincipal.requestFocus();

            }

            else
            {
                  // user clicks exit button
                  System.exit(0);
            }
      }

      public static void main(String[] args) throws IOException
      {
            Mortgage frame = new Mortgage();
                  frame.setTitle("Mortgage Payment Calculator");
                  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                  frame.setSize(600,400);
                  frame.setVisible(true);


      }//end main


      // The getPayment method accepts Monthly rate, months, and principal variables
      // and returns the monthly payment.
      public static double getPayment(double dRateMo, double iMonths, double dPrincipal)

      {

            return (dRateMo + (dRateMo / ((Math.pow((1+ dRateMo),iMonths)) - 1)))*dPrincipal;
      }//end getpayment

}//end class