how to add dropdown menu java mortgage calculator

Question

rrspen316 0 Newbie Poster

15 Years Ago

What I would like to do is to add a dropdown menu instead of having the buttons for the three loans. I tried a few different things but just cannot figure out how to do this and get it to work. Please can someone help? Here is my code with the buttons:

// import of the packages
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.*;

public class RSpencerMortCalcV2 extends JFrame implements ActionListener
{
	// variables declaration
	private JLabel labelamt, labelMonthlyPay, labeltitle, labelAmortTable, labelTerm, labelRate;
	private JButton button7, button15, button30, buttonReset, buttonQuit, buttonCalc;
	private JTextField textFieldAmount, textFieldMonthlyPayment, textFieldyears, textFieldinterest;
	private JComboBox jcb;
	private JTextArea taAmortTable;
	private JPanel contentPane;

	double interest, principle, bal, monthlyPay, Amount, Interest;
	int[] Years = {7, 15, 30};
	double[] Rate = {5.35, 5.50, 5.75};
	double Amt = Amount;
	int years;
	// end of variables declaration

	public RSpencerMortCalcV2()
	{
		super();
		initializeComponent();
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setVisible(true);
		pack();

		// add listeners
		button7.addActionListener(this);
		button15.addActionListener(this);
		button30.addActionListener(this);
		buttonCalc.addActionListener(this);
		buttonReset.addActionListener(this);
		buttonQuit.addActionListener(this);
	}

	public void initializeComponent()
	{
		// initialize labels and text fields
		labelamt = new JLabel(" Amount");
		labelMonthlyPay = new JLabel(" Monthly Payment");
		labeltitle = new JLabel("Mortgage Calculator");
		labelAmortTable = new JLabel("Amortization Table");
		labelTerm = new JLabel(" Years");
		labelRate = new JLabel(" Interest Rate");
		textFieldAmount = new JTextField("", 6);
		textFieldMonthlyPayment = new JTextField("", 8);
		textFieldyears = new JTextField("", 12);
		textFieldinterest = new JTextField("", 12);
		taAmortTable = new JTextArea(10, 300);

		JScrollPane scrollP = new JScrollPane(taAmortTable, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

		// initialize buttons
		button7 = new JButton("7 years at 5.35%");
		button7.setActionCommand("Calc7");
		button15 = new JButton("15 years at 5.5%");
		button15.setActionCommand("Calc15");
		button30 = new JButton("30 years at 5.75%");
		button30.setActionCommand("Calc30");
		buttonCalc = new JButton("Calculate");
		buttonCalc.setActionCommand("Calc");
		buttonReset = new JButton("Reset");
		buttonReset.setActionCommand("Reset");
		buttonQuit = new JButton("Quit");
		buttonQuit.setActionCommand("Quit");

		// set object attributes
		textFieldMonthlyPayment.setEditable(false);
		taAmortTable.setEditable(false);

		Container contentPane = getContentPane();

		// add the components to the panel
		contentPane.setLayout(null);
		addComponent(contentPane, labeltitle, 150,20,500,15);
		addComponent(contentPane, labelamt, 130,60,80,25);
		addComponent(contentPane, labelMonthlyPay, 130,220,100,25);
		addComponent(contentPane, labelAmortTable, 180,250,300,25);
		addComponent(contentPane, labelTerm, 130,85,80,40);
		addComponent(contentPane, labelRate, 130,125,80,25);
		addComponent(contentPane, textFieldAmount, 240,60,100,25);
		addComponent(contentPane, textFieldMonthlyPayment, 240,220,100,25);
		addComponent(contentPane, textFieldyears, 240,90,100,25);
		addComponent(contentPane, textFieldinterest, 240,125,100,25);
		addComponent(contentPane, button7, 35,170,130,30);
		addComponent(contentPane, button15, 180,170,130,30);
		addComponent(contentPane, button30, 320,170,135,30);
		addComponent(contentPane, scrollP, 50,280,400,270);
		addComponent(contentPane, buttonCalc, 50,570,100,30);
		addComponent(contentPane, buttonReset, 170,570,95,30);
		addComponent(contentPane, buttonQuit, 290,570,95,30);
	}

	public static void main(String[] args)
	{
		JFrame window = new RSpencerMortCalcV2();
		window.setTitle("Mortgage Calculator");
		window.setLocation(new Point(0, 0));
		window.setSize(new Dimension(500, 700));
	}

	// add component without a layout manager (Absolute Positioning)
	private void addComponent(Container container,Component c, int x, int y, int width, int height)
	{
		c.setBounds(x,y,width,height);
		container.add(c);
	}

	public void actionPerformed (ActionEvent e)
	{
		//perform action based on with button was pressed
		if ("Calc7".equals(e.getActionCommand()))
		{
			DecimalFormat decimalPlaces = new DecimalFormat("0.00");
			NumberFormat currency = NumberFormat.getCurrencyInstance();

			try // to validate user input of amount field
			{
				Amt = Double.parseDouble(textFieldAmount.getText());
			}
			catch(NumberFormatException event)
			{
				JOptionPane.showMessageDialog(null, "Enter Number Value Only for Amount!", "INVALID ENTRY", JOptionPane.ERROR_MESSAGE);
				return; // plain old "return" since it's in actionPerformed
			}

			double payment = CalcPay7();

			textFieldMonthlyPayment.setText("" + (currency.format(payment)));
			taAmortTable.setText("");
			taAmortTable.append("Payment \t Remaining \t\t  Interest\n");


			for(int i = 1; i <=(Years[0]*12); i++) // loop through monthly payment
			{
				bal=Amt; // set bal to loan

				// calculations on monthly payment
				interest = (((Rate[0]/100.0)/12.0)*bal); // monthly interest
				principle = (payment-interest); // applied towards principle
				Amt=(bal-principle); // loan balance after payment

				taAmortTable.append(i + " \t " + currency.format(Amt) + " \t\t " + currency.format(interest) + "\n"); // add to amort table
			} // end for
		} // end first if for button press

		else if ("Calc15".equals(e.getActionCommand()))
		{
			DecimalFormat decimalPlaces = new DecimalFormat("0.00");
			NumberFormat currency = NumberFormat.getCurrencyInstance();

			try // to validate user input of amount field
			{
				Amt = Double.parseDouble(textFieldAmount.getText());
			}
			catch(NumberFormatException event)
			{
				JOptionPane.showMessageDialog(null, "Enter Number Value Only for Amount!", "INVALID ENTRY", JOptionPane.ERROR_MESSAGE);
				return; // plain old "return" since it's in actionPerformed
			}

			double payment = CalcPay15();

			textFieldMonthlyPayment.setText("" + (currency.format(payment)));
			taAmortTable.setText("");
			taAmortTable.append("Payment \t Remaining \t\t  Interest\n");

			for(int i = 1; i <=(Years[1]*12); i++) // loop through monthly payment
			{
				bal=Amt; // set bal to loan

				// calculations on monthly payment
				interest = (((Rate[1]/100.0)/12.0)*bal); // monthly interest
				principle = (payment-interest); // applied towards principle
				Amt=(bal-principle); // loan balance after payment

				taAmortTable.append(i + " \t " + currency.format(Amt) + " \t\t " + currency.format(interest) + "\n"); // add to amort table
			} // end for
		} // end first if for button press

		else if ("Calc30".equals(e.getActionCommand()))
		{
			DecimalFormat decimalPlaces = new DecimalFormat("0.00");
			NumberFormat currency = NumberFormat.getCurrencyInstance();

			try // to validate user input of amount field
			{
				Amt = Double.parseDouble(textFieldAmount.getText());
			}
			catch(NumberFormatException event)
			{
				JOptionPane.showMessageDialog(null, "Enter Number Value Only for Amount!", "INVALID ENTRY", JOptionPane.ERROR_MESSAGE);
				return; // plain old "return" since it's in actionPerformed
			}

			double payment = CalcPay30();

			textFieldMonthlyPayment.setText("" + (currency.format(payment)));
			taAmortTable.setText("");
			taAmortTable.append("Payment \t Remaining \t\t  Interest\n");

			for(int i = 1; i <=(Years[2]*12); i++) // loop through monthly payment
			{
				bal=Amt; // set bal to loan

				// calculations on monthly payment
				interest = (((Rate[2]/100.0)/12.0)*bal); // monthly interest
				principle = (payment-interest); // applied towards principle
				Amt=(bal-principle); // loan balance after payment

				taAmortTable.append(i + " \t " + currency.format(Amt) + " \t\t " + currency.format(interest) + "\n"); // add to amort table
			} // end for
		} // end first if for button press

		else if("Calc".equals(e.getActionCommand()))
		{
			DecimalFormat decimalPlaces = new DecimalFormat("0.00");
			NumberFormat currency = NumberFormat.getCurrencyInstance();

			try // validate user input of all three text fields
			{
				Amt = Double.parseDouble(textFieldAmount.getText());
				years = Integer.parseInt(textFieldyears.getText());
				Interest = Double.parseDouble(textFieldinterest.getText());
			}
			catch(NumberFormatException event)
			{
				JOptionPane.showMessageDialog(null, "Enter Number Value Only for Amount, Years, and Interest!", "INVALID ENTRY", JOptionPane.ERROR_MESSAGE);
				return; // plain old "return" since it's in actionPerformed
			}

			double payment = CalcPay(); // to calculate if user selected to input all three fields

			textFieldMonthlyPayment.setText("" + (currency.format(payment)));
			taAmortTable.setText("");
			taAmortTable.append("Payment \t Remaining \t\t  Interest\n");

			for(int i = 1; i <=(years*12); i++) // for loop for amort table
			{
				bal=Amt; // set bal to loan

				// calculations on monthly payment
				interest = (((Interest/100.0)/12.0)*bal); // monthly interest
				principle = (payment-interest); // applied towards principle
				Amt=(bal-principle); // loan balance after payment

				taAmortTable.append(i + " \t " + currency.format(Amt) + " \t\t " + currency.format(interest) + "\n"); // add to amort table
			} // end for loop
		} // end of calc else if

		else if ("Reset".equals(e.getActionCommand()))
		{
			ResetFields(); // action command for reset button
		}

		else if ("Quit".equals(e.getActionCommand()))
		{
			System.exit(0); // action command for quit button
		}
	}

	public double CalcPay7()
	{
			// perform calculations if input is valid
			textFieldMonthlyPayment.setText("");
			double MonthPay = (loan() * (Rate[0]/100/12)) / (1 - Math.pow(1/(1 + (Rate[0]/100/12)), Years[0]*12));
			return MonthPay;
	}

	public double CalcPay15()
	{
			// perform calculations if input is valid
			textFieldMonthlyPayment.setText("");
			double MonthPay = (loan() * (Rate[1]/100/12)) / (1 - Math.pow(1/(1 + (Rate[1]/100/12)), Years[1]*12));
			return MonthPay;
	}

	public double CalcPay30()
	{
			// perform calculations if input is valid
			textFieldMonthlyPayment.setText("");
			double MonthPay = (loan() * (Rate[2]/100/12)) / (1 - Math.pow(1/(1 + (Rate[2]/100/12)), Years[2]*12));
			return MonthPay;
	}

	public double CalcPay()
	{
		// calculations for calc button
		textFieldMonthlyPayment.setText("");
		double MonthPay = (loan()* (Interest/100/12)) / (1 - Math.pow(1/(1 + (Interest/100/12)), years*12));
		return MonthPay;
	} // end of calc

	public void ResetFields()
	{
		// set all fields to blank
		textFieldAmount.setText("");
		textFieldMonthlyPayment.setText("");
		taAmortTable.setText("");
		textFieldyears.setText("");
		textFieldinterest.setText("");
	}

	public double loan()
	{
		double loan = Double.parseDouble(textFieldAmount.getText());
		return loan;
	}
}

java

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Latest Post 15 Years Ago Latest Post by BestJewSinceJC

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BestJewSinceJC 700 Posting Maven · Answer 1 · 2009-09-08T06:57:30+00:00

That is a lot of code - the short answer is that you'd use a JComboBox. It's fairly simple and there are plenty of examples here: http://java.sun.com/docs/books/tutorial/uiswing/components/combobox.html