/**
* setup a dummy mortgage payment that gives us a large set of values so that the table can resize
* its columns based on what is likely a "worst-case" scenario. this should leave plenty of room
* for real mortgage payments without making the window overly large and yet still reacting to
* local system visual sizes.
*/
private void sizeMortgageTable() {
resetMortgage();
final MortgagePayment p = new MortgagePayment(999999.99, 999999.99, 999999.99, 99999999.99);
paymentsModel.setPayments(new MortgagePayment[] {p});
paymentsTable.resizeTableColumns();
paymentsTable.limitTableViewport(VISIBLE_PAYMENT_TABLE_ROWS, true, false);
resetMortgage();
}
/**
* Utility method that will calculate a new mortgage payment and payment breakdown based on the
* user's current selection.
*/
private void calculateMortgage() {
boolean inputValid = true;
// fetch the new values from the data entry fields and calculate a
// new mortgage
double principal = 0.0;
try {
final String principalText = fieldPrincipal.getText();
principal = FMT_PRINCIPAL.parse(principalText).doubleValue();
if (principal <= 0.0) {
invalidInput(fieldPrincipal, MSG_PRINCIPAL_NEGATIVE);
inputValid = false;
}
} catch (ParseException ex) {
invalidInput(fieldPrincipal, MSG_INVALID_INPUT);
inputValid = false;
}
double rate = 0.0;
if (inputValid) {
try {
final String rateText = fieldRate.getText();
rate = FMT_RATE.parse(rateText).doubleValue();
if (rate <= 0.0) {
invalidInput(fieldRate, MSG_RATE_NEGATIVE);
inputValid = false;
}
} catch (ParseException ex) {
invalidInput(fieldRate, MSG_INVALID_INPUT);
inputValid = false;
}
}
int term = 0;
if (inputValid) {
try {
final String termText = fieldTerm.getText();
term = FMT_TERM.parse(termText).intValue();
if (term <= 0) {
invalidInput(fieldTerm, MSG_TERM_NEGATIVE);
inputValid = false;
}
} catch (ParseException ex) {
invalidInput(fieldTerm, MSG_INVALID_INPUT);
inputValid = false;
}
}
if (inputValid) {
// create a new Mortgage object from the selected mortgage terms and
// then update the principal with the user's requested value
final Mortgage mortgage = new Mortgage(principal, rate, term);
// format the mortgage payment into a user-friendly message
final Object[] values = {new Double(mortgage.getPayment())};
final String message = MessageFormat.format(MSG_PAYMENT, values);
// update our message label and payment data and force our UI
// to repaint itself with the new mortgage results
labelMessage.setText(message);
paymentsModel.setPayments(mortgage.getPayments());
// create a data set so the chart may be updated with the mortgage
// payment detail
final MortgagePayment[] payments = mortgage.getPayments();
final double[][] chartData = new double[2][payments.length];
for (int i = 0; i < payments.length; i++) {
chartData[0][i] = payments[i].getInterest().doubleValue();
chartData[1][i] = payments[i].getPrincipal().doubleValue();
}
final String[] chartDataNames = {"Interest", "Principal"};
final NumberFormat[] formats = {new DecimalFormat("#,##0"), new DecimalFormat("$ #,##0.00")};
paymentsChart.setData(chartData, chartDataNames, formats);
repaint();
}
}
/**
* Utility method that will reset the mortgage to an empty value and inform the user they need to
* recalculate.
*/
private void resetMortgage() {
labelMessage.setText(MSG_CALCULATE);
paymentsChart.clearData();
paymentsModel.setPayments(new MortgagePayment[0]);
repaint();
}
