Thread: Problem in implementing mortgage calculator

Right now I am supposed to create a mortgage calculator that would allow the user to select a length and interest, and then output the payment amount. The second step is to output how much of the loan is payed off each month, and then allowing the user to scroll through the list of months and amounts payed off.

So far, I have the calculations working, I just need to get the list working.

/****************************************************************/
/*                      MortgageCalc2	                            */
/*                                                              */
/****************************************************************/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MortgageCalc2 extends JFrame
{
	private double interest = 5.75;
	private double length = 30;
	private JLabel jLabel1;
	private JRadioButton ibutton1;
	private JRadioButton ibutton2;
	private JRadioButton ibutton3;
	private JTextField field_amount;
	private JTextField field_paymentamount;
	private JTextField field_paymentdisplay;
	private JButton button_calculate;
	private JButton button_clear;
	private JPanel contentPane;
	private ButtonGroup interestselect;
 
 
	public MortgageCalc2()
	{
		super();
		initializeComponent();
 
		this.setVisible(true);
	}
 
	private void initializeComponent()
	{
		jLabel1 = new JLabel();
		ibutton1 = new JRadioButton();
		ibutton2 = new JRadioButton();
		ibutton3 = new JRadioButton();
		field_amount = new JTextField();
		field_paymentamount = new JTextField();
		JTextArea field_paymentdisplay = new JTextArea();
		button_calculate = new JButton();
		button_clear = new JButton();
		contentPane = (JPanel)this.getContentPane();
		interestselect = new ButtonGroup();
 
		jLabel1.setText("Mortgage Amount:");
 
		ibutton1.setText("5 Year at 5.35% interest");
		ibutton1.addItemListener(new ItemListener() {
			public void itemStateChanged(ItemEvent e)
			{
				interest = 5.35;
				length = 7;
			}
 
		});
 
		ibutton2.setText("15 Year at 5.5% interest");
		ibutton2.addItemListener(new ItemListener() {
			public void itemStateChanged(ItemEvent e)
			{
				interest = 5.5;
				length = 15;
			}
 
		});
 
		ibutton3.setText("30 Year at 5.75% Interest");
		ibutton3.setSelected(true);
		ibutton3.addItemListener(new ItemListener() {
			public void itemStateChanged(ItemEvent e)
			{
				interest = 5.75;
				length = 30;
			}
 
		});
		field_amount.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e)
			{
				field_amount_actionPerformed(e);
			}
 
		});
		field_paymentamount.setText("-Monthly Payment Amount-");
		field_paymentamount.setEditable(false);
		field_paymentamount.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e)
			{
				field_paymentamount_actionPerformed(e);
			}
 
		});
		field_paymentdisplay.setText(" ");
		button_calculate.setText("Calculate");
		button_calculate.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e)
			{
				button_calculate_actionPerformed(e);
			}
 
		});
		button_clear.setText("Clear");
		button_clear.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e)
			{
				button_clear_actionPerformed(e);
			}
 
		});
 
		contentPane.setLayout(null);
		addComponent(contentPane, jLabel1, 13,10,95,18);
		addComponent(contentPane, ibutton1, 14,69,143,24);
		addComponent(contentPane, ibutton2, 14,92,143,24);
		addComponent(contentPane, ibutton3, 13,114,149,24);
		addComponent(contentPane, field_amount, 12,31,100,22);
		addComponent(contentPane, field_paymentamount, 15,154,134,22);
		addComponent(contentPane, field_paymentdisplay, 175,21,190,184);
		addComponent(contentPane, button_calculate, 14,223,83,28);
		addComponent(contentPane, button_clear, 103,223,83,28);
		interestselect.add(ibutton2);
		interestselect.add(ibutton1);
		interestselect.add(ibutton3);
		this.setTitle("MortgageCalc2 - extends JFrame");
		this.setLocation(new Point(0, 0));
		this.setSize(new Dimension(390, 300));
	}
 
	private void addComponent(Container container,Component c,int x,int y,int width,int height)
	{
		c.setBounds(x,y,width,height);
		container.add(c);
	}
 
	private void button_calculate_actionPerformed(ActionEvent e)
	{
		System.out.println("\nbutton_calculate_actionPerformed(ActionEvent e) called.");
 
 
				String amount1 = field_amount.getText();
				Float amount = new Float(amount1);
 
				double j = ( interest / ( 12 * 100 ) ) ;
				double n = ( length * 12 );
 
				double payment = ( amount * ( j / ( 1 - Math.pow( ( 1 + j ), -n ))));
				String payment2 = Double.toString(payment);
				field_paymentamount.setText(payment2);
 
				double paymentadd = 0;
				double paymentcount = 0;
 
				while (paymentadd<amount) {
				paymentadd = paymentadd + payment;
				paymentcount = paymentcount + 1;
				String doublepaymentadd1 = Double.toString(paymentadd);
				String doublepaymentcount1 = Double.toString(paymentcount);
				JTextArea.insert(doublepaymentadd1, doublepaymentcount1);
 
				}
	}
 
	private void button_clear_actionPerformed(ActionEvent e)
	{
		System.out.println("\nbutton_clear_actionPerformed(ActionEvent e) called.");
 
	}
}

Basically, in the large box to the right, I would like it too look like this:

1 AMOUNT
2 AMOUNT * 2
3 amount * 3

or

1 $100
2 $200
3 $400

If anyone could help me, that would be great.