Write the program in Java (with a graphical user interface) so that it will allow the user to select which way they want to calculate a mortgage: by input of the amount of the mortgage, the term of the mortgage, and the interest rate of the mortgage payment or by input of the amount of a mortgage and then select from a menu of mortgage loans:

- 7 year at 5.35%
- 15 year at 5.5 %
- 30 year at 5.75%

In either case, display the mortgage payment amount and then, list the loan balance and interest paid for each payment over the term of the loan. Allow the user to loop back and enter a new amount and make a new selection, or quit. Insert comments in the program to document the program.

*/

import java.awt.GridLayout.*;
import java.awt.event.ActionEvent.*;
import java.awt.event.ActionListener.*;
import java.text.NumberFormat.*;
import java.io.*;
import java.text.DecimalFormat.*;
import java.swing.*;
import java.text.*;


import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

class Week4Mortgage extends JFrame implements ActionListener
{
    //create applets
       private JLabel AmountofMortgage;
       private JLabel RateofMortgage;
       private JTextField PaymentofMortgage;
       private JLabel Interest;
       private JLabel TermofMortgage;
       private JTextField AmountEntered;
       private JTextField InterestEntered;
       private JTextField TermEntered;
       private JButton Calculate;
       private JButton Clear;
       private JButton Exit;

       //declare variables
       double AmountofMortgage;
       double PaymentofMortgage;
       double Interest;
       double TermofMortage;
       double RateofMortgage;


       public Week4Mortgage();
          {
              super ("Mortgage calculator");
                          setSize (400,200);
                          setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
                          setVisible (true);
                          Container calc = getContentPane();
                          calc.setBackground (Color.lightGray);
                          GridBagLayout gblm = new GridBagLayout();
                        GridLayout gridlayout= new GridLayout(5, 2, 20, 20);
                        //GridBagConstraints gbc = new GridBagConstraints();
                        calc.setLayout(gridlayout);

                        AmountofMortgage = new JLabel("Enter the Amount of Loan");

                                calc.add (AmountofMortgage,gridlayout);
                                AmountEntered = new JTextField ();

                                PaymentofMortgage = new JLabel("Enter the Payment of Loan");

                                calc.add (PaymentofMortgage,gridlayout);
                                AmountEntered = new JTextField();

                                Interest = JLabel("Enter the Interest of the Loan");

                                calc.add (Interest,gridlayout);
                                AmountEntered = new JTextField();

                                RateofMortgage = new JLabel("Enter the Rate of the Loan");

                                calc.add (RateofMortgage,gridlayout);
                                AmountEntered = new JTextField();


                                //Display action listeners
                                CalculateButton.addActionListener(this);
                                ClearButton.addActionListener(this);
                                ExitButton.addActionListener(this);



    public static void main(String []args)
    {
        Week4Mortgage frame = new Week4Mortgage();
}

//method to calculate mortgage payment
public void  actionPerformed(ActionEvent e)
{
    boolean done = false;
    Object command = e.getSource();

    //display event for calculate button clicked
    if(command = calculateButton)
    {
        try
        {
            double AmountofMortgage = Double.parseDouble(a.getText());
            double TermofMortgage = Double.parseDouble(t.getText());
            double RateofMortgage = Double.parseDouble(r.getText());
            double Interest = (rate/100/12);
            double PaymentofMortgage = (principal*interest)/(1-Math.pow(1/(1+interest), term*12));
            String displayPayment = money.format(payment);

            //Display decimal point format
        DecimalFormat decimalPlaces=new DecimalFormat("0.00");


        //does not allow 0 or null value
        if(principal <=0 || rate <=0 || term<=0) throw new NumberFormatException();
        else done = true;
    }
    // use this to catch exception
    catch(NumberFormatException e)
    {
        JOptionPane.showMessageDialog("Your Monthtly Payment is ");
        JOptionPane.showMessageDialog(null, "This calculation does not work, Please try something else!");

    }

}

//display the code if user clicks the clear button
else if(command == clearButton)
{
    p.setText(null);
    r.setText(null);
    displayPayment.setText(null);
    paymentLabel.setText("Click the calculate button to display the payment amount");
}

//display the exit code
else if(command == exitButton)
{
    System.exit(0);
}

}

}

}