calling other programs

I am working on an assignment for a gui mortgage program that calls a support program. I have modeled it after a sample program we recieved in class but am confused. Can someone look and see what I am missing?? any help is appreciated. the 2 programs are listed below:


1st program-
import javax.swing.*;
import java.awt.*;

public class ThursdayMortgageWeek3GUI extends JFrame {
      ThursdaySupportWeek3 mortgageSupport=new ThursdaySupportWeek3(this);


JPanel row10 = new JPanel();
JLabel amntLabel = new JLabel("Mortgage Amount: $", JLabel.LEFT);
JTextField loanField = new JTextField(10);


JPanel row20 =new JPanel();
JComboBox options = new JComboBox();
JLabel optionsLabel = new JLabel();
JLable lbltype= new JLable("Please select Term and APR for Mortgage",JLabel.Left);
JTextField years                  = new JTextField(2);

JPanel row30 = new JPanel();
JButton calButton = new JButton("Calculate");
JButton resetButton = new JButton("Reset");
JButton endButton = new JButton("End");

JPanel row40 = new JPanel();
JLabel paymtLabel = new JLabel("Monthly Payment Amount:");
JTextField paymtField = new JTextField();

JPanel row50 = new JPanel();
JLabel outputLabel = new JLabel("Loan Amoritization Table");
JLabel lblPaymentNum= new JLabel("Payment Number",JLabel.LEFT);
JLabel lblInterest= new JLabel("Interest",JLabel.LEFT);
JLabel lblPrinciple= new JLabel("Principal",JLabel.LEFT);
JLabel lblBalance= new JLabel("Balance",JLabel.LEFT);

JPanel row60 = new JPanel();
JTextArea textField = new JTextArea(5, 55);
JLabel lblText= new JLabel("Output");


public ThursdayMortgageWeek3GUI() {

super("Week 3 - Mortgage GUI");
setSize(650,500);
setLocation(250,60);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Font f = new Font ("Arial", Font.PLAIN, 30);
Font b = new Font ("Arial", Font.BOLD, 16);
FlowLayout layout = new FlowLayout();
Container pane = getContentPane();
pane.setLayout(layout);


loanField.addActionListener(mortgageSupport);
options.addActionListener(mortgageSupport);
calButton.addActionListener(mortgageSupport);
resetButton.addActionListener(mortgageSupport);
endButton.addActionListener(mortgageSupport);

FlowLayout flow10 = new FlowLayout();
row10.setLayout(flow10);
row10.add(amntLabel);
row10.add(loanField);
pane.add(row10);


GridLayout flow20 = new GridLayout(1,4,5,1);
row20.setLayout(flow20);
row20.add(optionsLabel);
row20.add(options);
row20.add(lbltype)
options.setEnabled(true);
options.addItem("Select Option");
options.addItem("7 year at 5.35%");
options.addItem("15 year at 5.5%");
options.addItem("30 year at 5.75%");
pane.add(row20);


GridLayout flow30 = new GridLayout (1,4,75,1);
row30.add(calButton);
row30.add(resetButton);
row30.add(endButton);
pane.add(row30);

FlowLayout flow40 = new FlowLayout();
row40.setLayout(flow40);
paymtField.setLineWrap(true);
JScrollPane textpane= new JScrollPane(paymntField,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
row40.add(paymtLabel);
row40.add(paymtField);
pane.add(row40);

Grid Layout flow50= new GridLayout(1,4,5,1);
row50.setLayout(flow50);
rbTermInterest.setFont(b);
row50.add(outputLabel);
row50.add(lblPaymentNum);
row50.add(lblInterest);
row50.add(lblPrinciple);
row50.add(lblBalance);
pane.add(row50);      

FlowLayout flow60 = new FlowLayout();
txtResults.setLineWrap(true);
row60.setLayout(flow60);
JScrollPane textpane= new JScrollPane(paymntField,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
row60.add(lblText);
row60.add(textField);
pane.add(row60);


}

public static void main(String[] args) {
      ThursdayMortgageWeek3GUI guiFrame= new ThursdayMortgageWeek3GUI();
      guiFrame.setVisible(true);
      }
}
      
_______________________________________________________________________________

2nd program :

import java.awt.event.*;
import java.text.*;
import java.lang.*;
import java.io.*;

public class ThursdaySupportWeek3 implements ItemListener,ActionListener
{

ThursdayMortgageWeek3GUI gui;
double amount = 0;
double term = 0;
double intrst = 0;
double moIn = 0;
double moTrm = 0;
double prin = 0;
double payment = 0;
double termArray[] = { 7, 15, 30 };
double intrstArray[] = { 5.35, 5.50, 5.75 };

//to format payment amounts
DecimalFormat df = new DecimalFormat("$#,###.00");

public ThursdaySupportWeek3(ThursdayMortgageWeek3GUI  in)
{
gui=in;
}
public static void main(String []  args)
{
}
//

public void itemStateChanged(ItemEvent arg0) {

Object button = gui.options.getSelectedItem();
String buttonPress = button.toString();

Object source = event.getSource();

if (buttonPress == calButton) {
startCalculations();

}
if (buttonPress == resetButton) {
reset();

}
if (buttonPress == endButton) {
end();

}
}

public void actionPerformed(ActionEvent event)
{
      String buttonClicked = event.getActionComman();
      if (buttonClicked == "Select Option")
            setComboBoxNull();
      if (buttonClicked == "Select Option" && !gui.options.isSelected())
            clearResults();
            
      if (buttonClicked =="Calculate" && gui.options.isSelected())
            {
            try
            {
            amount = Double.parseDouble(loanField.getText());
                  } catch (NumberFormatException e) {
                  clearResults();
                  gui.textField.append("Please Do Not Use Commas.Invalid Entry");
                  loanField.setText(null);

}

termArray[0]=Double.parseDouble(txtYears);
intrstArray[0]=Double.parseDouble(txtIntRate);
array=0;
clearResults();
funcCalculate();
}

if (buttonClicked =="Calculate")
{
      clearResults();
      funcCalculate();
      }
if (buttonClicked == "Clear")
      setNull();
if (buttonClicked =="Exit")
      System.exit(0);
}
      
void startCalculations() {

do
{
            NumberFormat fmt = NumberFormat.getInstance();
            fmt.setGroupingUsed (true);
            fmt.setMaximumFractionDigits(2);
            fmt.setMinimumFractionDigits(2);
            String txtInitialAmount = gui.txtAmount.getText();
            gui.options.setEnabled(true);
            gui.calButton.setEnabled(true);

double newPrin = amount;
double newIn = moIn * newPrin;
double reduction = payment - newIn;
newPrin = newPrin - reduction;


for (int i = 0; i < options[Array]; i++) {
options.addItem(optionsArray[i]);
}
}
while (c<=options[Array]);
}

int index = options.getSelectedIndex();
term = termArray[index];
intrst = intrstArray[index];

if (amount > 0) {
amount = Double.parseDouble(loanField.getText());
moIn = (intrst / 12) / 100;
moTrm = term * 12;
payment = amount * (moIn / (1 - java.lang.Math.pow((1 + moIn), (-moTrm))));

paymtField.setText("" + df.format(payment));

textField.append("Payment#");
textField.append(" ");
textField.append("Payment Amount");
textField.append(" ");
textField.append("Interest");
textField.append(" ");
textField.append("Principle");
textField.append(" ");
textField.append("");
textField.append(" \n");



for (int i = 1; i <= moTrm; i++) {


textField.append(" " + i);
textField.append(" " + df.format(payment));
textField.append(" " + df.format(newIn));
textField.append(" " + df.format(reduction));
textField.append(" " + df.format(newPrin) + "\n");

}

}
if (amount < 0) {
JOptionPane.showMessageDialog(null, "Please Enter Valid Amount",
"Message Dialog", JOptionPane.PLAIN_MESSAGE);
loanField.setText(null);
}
}

void reset() {

loanField.setText(null);
paymtField.setText(null);

}

void end() {
System.exit(0);
}

}
}