import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*;

public class ModifiedFutureValueApp
{
    public static void main(String[] args)
    {
        JFrame frame = new FutureValueFrame();
        frame.setVisible(true);
    }
}

class FutureValueFrame extends JFrame
{
    public FutureValueFrame()
    {
        setTitle("Future Value Calculator");
        centerWindow(this);
        setSize(400, 400);
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel panel = new FutureValuePanel();
        getContentPane().add(panel);
    }

    private void centerWindow(Window w)
    {
        Toolkit tk = Toolkit.getDefaultToolkit();
        Dimension d = tk.getScreenSize();
        setLocation((d.width-w.getWidth())/2, (d.height-w.getHeight())/2);
    }
}

class FutureValuePanel extends JPanel implements ActionListener
{
    private JTextField  paymentTextField,
                        rateTextField;
     private JTextArea   futureValueTextArea;
     private JScrollPane scrollPane;
    private JLabel      paymentLabel,
                        rateLabel,
                        yearsLabel,
                        futureValueLabel;
    private JButton     calculateButton,
                        exitButton;
     private JComboBox   yearsComboBox;

    public FutureValuePanel()
    {
        setLayout(new GridBagLayout());

        // payment label
        paymentLabel = new JLabel("Monthly Payment:");
        add(paymentLabel, getConstraints(0,0,1,1, GridBagConstraints.EAST));

        // payment text field
        paymentTextField = new JTextField(15);
        add(paymentTextField, getConstraints(1,0,1,1, GridBagConstraints.WEST));

        // rate label
        rateLabel = new JLabel("Yearly Interest Rate:");
        add(rateLabel, getConstraints(0,1,1,1, GridBagConstraints.EAST));

        // rate text field
        rateTextField = new JTextField(15);
        add(rateTextField, getConstraints(1,1,1,1, GridBagConstraints.WEST));

        // years label
          yearsLabel = new JLabel("Number of Years:");
        add(yearsLabel, getConstraints(0,2,1,1, GridBagConstraints.EAST));
          
          //years combo box
          String[] years = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10",
          "11", "12", "13", "14", "15", "16", "17", "18", "19", "20" };
        yearsComboBox = new JComboBox(years);
          yearsComboBox.setSelectedIndex(0);
          yearsComboBox.addActionListener(this);
        add(yearsComboBox, getConstraints(1,2,1,1, GridBagConstraints.WEST));


        // future value label
        futureValueLabel = new JLabel("Future Value:");
        add(futureValueLabel, getConstraints(0,3,1,1, GridBagConstraints.EAST));

        // future value text field
          JTextArea futureValueTextArea = new JTextArea(5, 15);
          JScrollPane scrollPane = new JScrollPane(futureValueTextArea,
                  ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,
                ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
          futureValueTextArea.setEditable(false);
        add(scrollPane, getConstraints(1,3,1,1, GridBagConstraints.WEST));

        // calculate button
        calculateButton = new JButton("Calculate");
        calculateButton.addActionListener(this);
        add(calculateButton, getConstraints(1,4,1,1, GridBagConstraints.CENTER));

        // exit button
        exitButton = new JButton("Exit");
        exitButton.addActionListener(this);
        add(exitButton, getConstraints(2,4,1,1, GridBagConstraints.WEST));
          
    }

    public void actionPerformed(ActionEvent e)
    {
        Object source = e.getSource();
        if (source == exitButton)
            System.exit(0);
        else if (source == calculateButton)
        {
            double payment = Double.parseDouble(paymentTextField.getText());
            double rate = Double.parseDouble(rateTextField.getText());
                int years = yearsComboBox.getSelectedIndex();
            double futureValue = FinancialCalculations.calculateFutureValue(
                payment, rate, years);
            NumberFormat currency = NumberFormat.getCurrencyInstance();
                String result = currency.format(futureValue);
                futureValueTextArea.setText(result);
        }
    }
     private GridBagConstraints getConstraints(int gridx, int gridy, int gridwidth
     , int gridheight, int anchor)
     {
         GridBagConstraints c = new GridBagConstraints();
        c.insets = new Insets(5, 5, 5, 5);
        c.ipadx = 0;
        c.ipady = 0;
        c.gridx = gridx;
        c.gridy = gridy;
        c.gridwidth = gridwidth;
        c.gridheight = gridheight;
        c.anchor = anchor;
        return c;
     }
}

          JTextArea futureValueTextArea = new JTextArea(5, 15);

               futureValueTextArea.setText(result);

          futureValueTextArea = new JTextArea(5, 15);   // access the real one