Event Handling

dakotasw — GMT

Hi

I have to do a mortgage program using graphical user interface. The user can input any amount for the principal of the loan and then have three options for a payment plan. The program should display the mortgage payment then list the loan balance and interest paid for each payment over the life of the loan.

I did the code but there is an event error and I cannot seem to understand why the error is there. The code is attached below. Any assistance would be appreciated.

[code]

import java.text.*;
import java.awt.*;
import java.io.*;
import java.awt.event.*;
import java.lang.Math.*;
import javax.swing.*;

public class MortgageCalcOptions extends JFrame implements ActionListener{

//Declare variables & loan array and initialize with values
//Declares the various button, text fields and labels for the calculator.

JButton calculate, clear; //Declares the calculate and clear data buttons.
JTextField tmortgamt, tmortgpmt; //Declares the text field for the mortgage amount.
JLabel lmortgamt, lmortgage, lmortgpmt, lmortgdetails; //Declares the label boxes for mortgage amount and mortgage details.
JRadioButton select7, select15, select30; //Declares the radio buttons to make term and interest rate selections
JScrollPane backpanel; //List of monthly payments and interest paid per month

java.text.DecimalFormat dec = new java.text.DecimalFormat(",###.00"); //Decimal format

int[] mortgtrm = {7, 15, 30}; //Initialises the array for the three different years.
double[] mortgir = {5.35, 5.5, 5.75}; //Initialises the array for the three different interest rates.
double mortgamt = Double.parseDouble(tmortgamt.getText());

//Sets constraints on the lay out of the interface of the calculator.

public MortgageCalcOptions() {
setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();

//Creating, formatting and position and orientation of each component on the calculator interface.
//Set the size of the buttons, labels and text fields.

lmortgamt = new JLabel("Amount ");
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 0;
c.gridy = 0;
c.gridwidth = 1;
add(lmortgamt, c);

tmortgamt = new JTextField(15);
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 1;
c.gridy = 0;
c.gridwidth = 3;
add(tmortgamt, c);

lmortgpmt = new JLabel("Payment ");
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 0;
c.gridy = 3;
c.gridwidth = 1;
add(lmortgpmt, c);

tmortgpmt = new JTextField(15);
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 1;
c.gridy = 3;
c.gridwidth = 3;
add(tmortgpmt, c);

lmortgage = new JLabel("Mortgage Details ");
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 0;
c.gridy = 4;
c.gridwidth = 1;
add(lmortgage, c);

lmortgdetails = new JLabel("");
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 0;
c.gridy = 5;
c.gridwidth = 1;
add(lmortgdetails, c);

calculate = new JButton("Calculate");
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 1;
c.gridy = 6;
c.gridwidth = 1;
add(calculate, c);

clear = new JButton("Clear Data");
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 2;
c.gridy = 6;
c.gridwidth = 1;
add(clear, c);

backpanel = new javax.swing.JScrollPane();
backpanel.setPreferredSize(new Dimension(300, 400));
backpanel.setVerticalScrollBarPolicy(javax.swing.ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
backpanel.setBorder(javax.swing.BorderFactory.createBevelBorder(javax.swing.border.BevelBorder.LOWERED));

select7 = new JRadioButton("7 Years at 5.35%", false);
select7.setActionCommand("sel7");

select15 = new JRadioButton("15 Years at 5.50%", false);
select15.setActionCommand("sel15");

select30 = new JRadioButton("30 Years at 5.75%", false);
select30.setActionCommand("sel30");

ButtonGroup group = new ButtonGroup(); //Create button group
group.add(select7);
group.add(select15);
group.add(select30);

//Creates the event of the buttons calculate and clear data to perform.
//The calculate button will calculate the mortgage payment and the clear data button will.
//allow the user to clear the fields and enter new data.

event a = new event();
calculate.addActionListener(a);
clear.addActionListener(a);

}

public void actionPerformed(ActionEvent a) {

for (int i = 0; i < mortgir.length; i++)
{
// Formula to calculate one month's mortgage payment
double mortgpmt = (mortgamt * (mortgir[i]/12/100)) / (1-(Math.pow(1/(1+(mortgir[i]/12/100)),(mortgtrm[i]*12))));

// Formula to calculate the total amount paid over life of the loan
double tottobepd = (mortgtrm[i]*12) * mortgpmt;

// Formula to calculate the total interest paid over life of the loan
double totinttobepd = tottobepd - mortgamt;

//Declares and builds additional variables for caluclations
double mortgbal = mortgamt;
double balance = tottobepd;
double intbalance = totinttobepd;
double mortpdsofar = 0.0;
double intpaidsofar = 0.0;
double noofpayments = 0;
double intpdthismth;

//When the calculate button is pressed the payment is calculated and shown in the payment field according to the mortgage plan.
//Also when the clear data button is pressed all fields are set to null.

String arg = event.getActionCommand();
String op = a.getActionCommand();

if(op.equals("Clear Data")) {
tmortgamt.setText(null);
tmortgpmt.setText(null);
}

else if (op.equals("Calculate")) {

if (arg == "sel7"){
double mortgamt = Double.parseDouble(tmortgamt.getText());
mortgpmt = (mortgamt * (mortgir[i]/12/100)) / (1-(Math.pow(1/(1+(mortgir[i]/12/100)),(mortgtrm[i]*12))));
tmortgpmt.setText(""+ dec.format(mortgpmt));
lmortgdetails = new JLabel("Payment Number\tLoan Balance\t\tInterest");

//This will start the loop statement and declares formula for loan balance and interest paid
while (balance > 0.0){

}
intpdthismth = mortgbal * (mortgir[i]/12/100);
mortgbal = mortgbal - (mortgpmt - intpdthismth);
mortpdsofar = mortpdsofar + (mortgpmt - intpdthismth);
intbalance = intbalance - intpdthismth;
intpaidsofar = intpaidsofar + intpdthismth;
balance = balance - mortgpmt;
noofpayments = noofpayments + 1;

//Displays the loan balance and interest paid
lmortgdetails = new JLabel(noofpayments+"\t\t"+"$" + dec.format(balance)+"\t\t"+"$" + dec.format(intpdthismth));

}

if (arg == "sel15"){
double mortgamt = Double.parseDouble(tmortgamt.getText());
mortgpmt = (mortgamt * (mortgir[i]/12/100)) / (1-(Math.pow(1/(1+(mortgir[i]/12/100)),(mortgtrm[i]*12))));
tmortgpmt.setText(""+ dec.format(mortgpmt));
lmortgdetails = new JLabel("Payment Number\tLoan Balance\t\tInterest");

//This will start the loop statement and declares formula for loan balance and interest paid
while (balance > 0.0){

}
intpdthismth = mortgbal * (mortgir[i]/12/100);
mortgbal = mortgbal - (mortgpmt - intpdthismth);
mortpdsofar = mortpdsofar + (mortgpmt - intpdthismth);
intbalance = intbalance - intpdthismth;
intpaidsofar = intpaidsofar + intpdthismth;
balance = balance - mortgpmt;
noofpayments = noofpayments + 1;

//Displays the loan balance and interest paid
lmortgdetails = new JLabel(noofpayments+"\t\t"+"$" + dec.format(balance)+"\t\t"+"$" + dec.format(intpdthismth));

}

if (arg == "sel30"){
double mortgamt = Double.parseDouble(tmortgamt.getText());
mortgpmt = (mortgamt * (mortgir[i]/12/100)) / (1-(Math.pow(1/(1+(mortgir[i]/12/100)),(mortgtrm[i]*12))));
tmortgpmt.setText(""+ dec.format(tmortgpmt));
lmortgdetails = new JLabel("Payment Number\tLoan Balance\t\tInterest");

//This will start the loop statement and declares formula for loan balance and interest paid
while (balance > 0.0){

}
intpdthismth = mortgbal * (mortgir[i]/12/100);
mortgbal = mortgbal - (mortgpmt - intpdthismth);
mortpdsofar = mortpdsofar + (mortgpmt - intpdthismth);
intbalance = intbalance - intpdthismth;
intpaidsofar = intpaidsofar + intpdthismth;
balance = balance - mortgpmt;
noofpayments = noofpayments + 1;

//Displays the loan balance and interest paid
lmortgdetails = new JLabel(noofpayments+"\t\t"+"$" + dec.format(balance)+"\t\t"+"$" + dec.format(intpdthismth));

}

}
}
}

public static void main(String args[]) {

//Sets the size of the calculator interface window, as well as set a lable for it.
//And allows the user to close the window if so desired.

MortgageCalcOptions gui = new MortgageCalcOptions();
gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
gui.setVisible(true);
gui.setSize(480,600);
gui.setTitle("Mortgage Calculator");

}
}

[/code]

Re:Event Handling

dakotasw — GMT

I forgot to add the error I am getting when I try to compile it. I am using NetBeans so the errors are already shown before I compile. The error is below:

MortgageCalcOptions.java:131: error: cannot find symbol
event a = new event();
^
symbol: class event
location: class MortgageCalcOptions
MortgageCalcOptions.java:131: error: cannot find symbol
event a = new event();
^
symbol: class event
location: class MortgageCalcOptions
MortgageCalcOptions.java:164: error: cannot find symbol
String arg = event.getActionCommand();
^
symbol: variable event
location: class MortgageCalcOptions
3 errors

Re:Event Handling

stdunbar — GMT

Remember that Java is case sensitive - there is no event class but there is an Event class.

And just some feedback - do yourself a favor and name your variables like a human is going to read your code. It doesn't cost anything to name your variables in a way that makes sense - 'a' is far harder to figure out than something like actionListenerEvent.

Event Handling

chowbaaron — GMT

To help you out in the future, classes generally start with an Uppercase letter. Therefor, whenever you get an error like:

symbol: class event
location: class MortgageCalcOptions
MortgageCalcOptions.java:131: error: cannot find symbol
event a = new event();
^

see that they are talking about "class event". This should tell you that "event" should be "Event".

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