Mortgage Calculator GUI

// Importing Class
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.NumberFormat;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.JTextArea;
import javax.swing.JComboBox;
import javax.swing.JRadioButton;
import javax.swing.ButtonGroup;
import javax.swing.SwingConstants;
import javax.swing.SwingUtilities;


import javax.swing.UIManager;
import javax.swing.UIManager.LookAndFeelInfo;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.table.DefaultTableModel;

import java.text.DecimalFormat;   //For display the monthly payments as money




// Create Mortgage Payment Class
public class MortgageCalculator extends JFrame {

      static  String mortgage[] = {"Select Mortgage","10 years at 5.35%","20 years at 5.5%","30 years at 5.75%"};
      static String [] toReplace;
         DecimalFormat money = new DecimalFormat("$###,###.00");

   // Define the JPanel where we will draw and place all of our components.
    JPanel contentPanel = null;

    // GUI elements to display labels, fields, table, scoll pane for current information
    JLabel main_title = null;

    JLabel principal_label = null;
    JTextField principal_text = null;

    JLabel years_label = null;
    JTextField years_text = null;

    JLabel rate_label = null;
    JTextField rate_text = null;

    JLabel choose_label = null;
    JComboBox choose_combo = null;

    JRadioButton rbutton01 = null;
    JRadioButton rbutton02 = null;

    ButtonGroup buttongroup = null;

    //GUI text area for results with scroll pane
    JTextArea result = null;
    JScrollPane scrolling_result = null;

    //GUI for Table with scroll pane
    MyJTable total_amounts = null;
    JScrollPane scrolling_table = null;
    MyDTableModel model;

    // creates the button for calculation of the mortgage payments
    JButton btnCalculate = null;
    // Creates a button for reset button
    JButton btnReset = null;

     // Declaration of variables

        int numberOfLinesGenerated=1;
        double number_years; //term mortgage
        double principal; // amount borrowed
        double interest_rate;  // interest for mortgage
        double monthly_payment;  // monthly payment for mortgage
        double monthly_interest_rate ; // monthly interest
        double number_of_months; // number of months for mortgage payments
        double interest_paid; //interest amount added for each month
        double principal_paid;


     //This is the class constructor - initialize the components

    public MortgageCalculator() {
        super();
        initialize();
    }

    public void initialize() {
        // Defines the window size of 600px by 500 px
        this.setSize(700, 600);
        // The JPanel is where all the components are places.
        this.setContentPane(getJPanel());
        // Define the title of the window.
        this.setTitle("McBride Financial Services Mortgage Calculator");
    }

    public JPanel getJPanel() {
        if (contentPanel == null) {
            // initializes the contentPanel
            contentPanel = new JPanel();
            // Set the Panel to null to put the components into the panel
            contentPanel.setLayout(null);

            contentPanel.setBackground(new Color(38,44,125));

            // GUI elements to display labels and fields for current information

            // Main Title of the Calculator
            main_title = new JLabel();
            //This will center the label
            main_title.setHorizontalAlignment(SwingConstants.CENTER);
            // Set the boundary of this label
            main_title.setBounds(200, 20, 300, 30);
            // Sets the title to application
            main_title.setText("Mortgage Calculator");
            //sets the font size and font
            main_title.setFont(new Font("Serif", Font.PLAIN, 27));
           //sets the font color
            main_title.setForeground(Color.white);

            // Add the Title to the  contentPanel
            contentPanel.add(main_title);

            //Principal Label
            principal_label = new JLabel();
            //This will align the label right
            principal_label.setHorizontalAlignment(SwingConstants.RIGHT);
            // Set the boundary of this label
            principal_label.setBounds(90, 65, 220, 25);
            // Sets the label text
            principal_label.setText("Mortgage Principal : ");
            //sets the font size and font
            principal_label.setFont(new Font("Sans Serif", Font.BOLD, 14));
            //sets the font color
            principal_label.setForeground(Color.white);
            //Adds it to the contentPanel
            contentPanel.add(principal_label);

            //Principal Text Field
            principal_text = new JTextField();
            // Set the boundary of this text field
            principal_text.setBounds(350, 65, 160, 25);
            //sets what it entered in text field
            principal_text.setText(Double.toString(principal));
            //Adds it to the contentPanel
            contentPanel.add(principal_text);

             //Number of Years Label
            years_label = new JLabel();
            years_label.setHorizontalAlignment(SwingConstants.RIGHT);
            years_label.setBounds(90, 125, 220, 25);
            years_label.setText("Mortgage Term : ");
            years_label.setFont(new Font("Sans Serif", Font.BOLD, 14));
            years_label.setForeground(Color.white);
            contentPanel.add(years_label);

            //Number of Years Text Field
            years_text = new JTextField();
            years_text.setBounds(350, 125, 160, 25);
            years_text.setText(Double.toString(number_years));
            contentPanel.add(years_text);

            //Annual Interest Rate Label
            rate_label = new JLabel();
            rate_label.setHorizontalAlignment(SwingConstants.RIGHT);
            rate_label.setBounds(90, 165, 220, 25);
            rate_label.setText("Annunal Interest Rate : ");
            rate_label.setFont(new Font("Sans Serif", Font.BOLD, 14));
            rate_label.setForeground(Color.white);
            contentPanel.add(rate_label);

            //Annual Interest Rate  Text Field
            rate_text = new JTextField();
            rate_text.setBounds(350, 165, 160, 25);
            rate_text.setText(Double.toString(interest_rate * 100) + "%");
            contentPanel.add(rate_text);

           

            //Text Area for result
            result = new JTextArea(5, 20);
            result.setBounds(170, 250, 350, 75);
            scrolling_result = new JScrollPane(result);
            contentPanel.add(result);

            //Table for calculations
            total_amounts = new MyJTable();
            scrolling_table = new JScrollPane (total_amounts);
            scrolling_table.setBounds(20, 350, 650, 200);
            contentPanel.add(scrolling_table);


            // Creates a button for reset button
            btnReset = new JButton ();
            btnReset.setBounds(355, 200, 90, 30);
            btnReset.setText("Reset");
            contentPanel.add(btnReset);


            // creates the button for calculation of the mortgage payments
            btnCalculate = new JButton ();
            btnCalculate.setBounds(245, 200, 90, 30);
            btnCalculate.setText("Calculate");
            contentPanel.add(btnCalculate);




            // Adds the action listerner to  the reset button
            btnReset.addActionListener(new ActionListener()
            {
                public void actionPerformed(ActionEvent e)
                {
                // Calls the onButtonReset() method
                onButtonReset();
                 }
            });

           // This is the main area that when the calculate button is pressed,
            // will grab the values from the text fiedl and the combo box,
            // Calcutes the montly payment adds to result text area
            //and adds it to the table.
            btnCalculate.addActionListener(new ActionListener() {
                // Get the values for each of the field
                public void actionPerformed(ActionEvent e) {
                  principal=getDouble(principal_text.getText());
						interest_rate=getDouble(rate_text.getText());
						number_years=getDouble(years_text.getText());


                    {
                                    //calculates the number of months for mortgage
                    //This determines the number of payments to be made
                    number_of_months = number_years * 12;

                    //caluclates the monthly interest rate
                    monthly_interest_rate = interest_rate/12.0;

                    //Calculates the monthly payment for mortgage
                    monthly_payment = (principal* monthly_interest_rate)/(1 - Math.pow(1 + monthly_interest_rate, -number_of_months));


                   // Sets the result text
                    result.setText("Loan Amount = " + money.format(principal)
                    +"\nInterest Rate = " + (interest_rate * 100) +"%"+"\nLength of Loan = "
                    + Math.round(number_years * 12.0) + " months"+"\nMonthly Payment = "
                    + money.format(monthly_payment)); //calling the monthly_payment

                    // Have the necessary information for the model lets recalculate it.
                    if(total_amounts != null){
                        total_amounts.setModel(getModel());
                    }

                
            //Adds the calculate button
            contentPanel.add(btnCalculate);

            //Adds the scroll pane
            contentPanel.add(getScrollPane());
        }

        return contentPanel;
    }




    // This the Scroll pane for the table - sets the boundary
    public JScrollPane getScrollPane() {
        if (scrolling_table == null) {
            scrolling_table = new JScrollPane();
            scrolling_table.setBounds(65, 225, 425, 120);
            scrolling_table.setViewportView(getTable());
        }
        return scrolling_table;
    }

    public JTable getTable() {
        if (total_amounts == null) {
                total_amounts = new MyJTable(getModel());
        }
        return total_amounts;
    }

    //this will calculate the model for the table over and over again.
    public MyDTableModel getModel() {
        String[] columnNames = {"Payment Number", "Begin Balance", "Monthly Payment","Interest Paid","Principal Paid", "Ending Balance"};

        model = null;
        model = new MyDTableModel();
        for (int i = 0; i < 6; i++) {
            model.addColumn(columnNames[i]);
        }

        // This is the necessary data to calculate the table
        if (principal > 0 && interest_rate != 0 && number_years != 0) {
            double new_principal = principal;
            NumberFormat nf = NumberFormat.getCurrencyInstance();
            for (int i = 0; i < number_of_months; i++) {
                Object data[] = new Object[6];
                 data[0] = Integer.toString(i + 1);
                data[1] = nf.format(new_principal);
                data[2] = nf.format(monthly_payment);
                data[3] = nf.format(interest_paid = principal * monthly_interest_rate);
                data[4] = nf.format(principal_paid = monthly_payment - interest_paid);
                data[5] = nf.format(principal = principal - principal_paid);
                new_principal = principal;

                model.addRow(data);
            }
        }
        return model;
    }

    /**
     * The following will parse a double value from entered string
     * If the number is entered with a dollar sign, than parse it
     * one way otherwise parse it using the default number.
     * If there is an error, then zero will be returned
     * @return value
     */
    public double getDouble(String val) {
        double value = 00;
        try {
            // this tests to see if there is a dollar sign, if there
            // is it uses the currency number formater, otherwise just
            // the number formatter.
            if (val.indexOf('$') > -1) {
                // we need to use the currency expression
                value = NumberFormat.getCurrencyInstance().parse(val).doubleValue();
            } else {
                value = NumberFormat.getNumberInstance().parse(val).doubleValue();
            }
        } catch (java.text.ParseException e) {
            // Generates an error here, can add a JOptionDialog to display the
            // text and the error
            JOptionPane.showMessageDialog(this, "There is an error " + val + ". Please check your entry", "Data Entry Error", JOptionPane.ERROR_MESSAGE);
        }
        return value;
    }

    /**
     * The following will parse a string with a percent or no percent sign, and then divide it to decimal format.
     * @param val
     * @return
     */
    public double getPercent(String val) {
        boolean isPercent = false;
        double value = 0;
        try {
            if (val.indexOf('%') > -1) {
                value = NumberFormat.getPercentInstance().parse(val).doubleValue();
                isPercent = true;
            } else {
                value = NumberFormat.getNumberInstance().parse(val).doubleValue();
            }
        } catch (java.text.ParseException e) {
            JOptionPane.showMessageDialog(this, "There is an error " + val + ". Please check your entry", "Data Entry Error", JOptionPane.ERROR_MESSAGE);
        }

        // Have a percentage already in decimal format
        if(!isPercent)
            value = value/100.0;

        return value;
    }

      // Information for  Reset Button
         public void onButtonReset(){

        // Resets the fields
        principal_text.setText("");
        result.setText("");
        total_amounts.setModel(new MyDTableModel());

    }

    
    public static void main(String[] args) {
        
        SwingUtilities.invokeLater(new Runnable() {

            public void run() {
                MortgageCalculator thisClass = new MortgageCalculator();
                thisClass.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                thisClass.setVisible(true);
					 }
					 }
					 }
               
    

   
 
		  

    

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