// calculate and display amounts
private void calculateJButtonActionPerformed(ActionEvent event) {
// declare variables to store user input
double principal = Double.parseDouble(principalJTextField.getText());
double rate = Double.parseDouble(interestRateJTextField.getText());
Integer integerObject = (Integer) yearsJSpinner.getValue();
Integer year = integerObject.intValue();
yearlyBalanceJTextArea.setText("Year\tAmount on Deposit");
DecimalFormat dollars = new DecimalFormat("$0.00");
// calculate the total value for each year
for (int count = 1; count <= year; count++) {
double amount = principal * Math.pow((1 + rate / 100), count);
yearlyBalanceJTextArea.append("\n" + count + "\t" + dollars.format(amount));
} // end for
} // end method calculateJButtonActionPerformed
// create and position GUI components; register event handlers
private void createUserInterface() {
// get content pane for attaching GUI components
Container contentPane = getContentPane();
// enable explicit positioning of GUI components
contentPane.setLayout(null);
// set up principalJLabel
principalJLabel = new JLabel();
principalJLabel.setBounds(16, 16, 56, 24);
principalJLabel.setText("Principal:");
contentPane.add(principalJLabel);
// set up principalJTextField
principalJTextField = new JTextField();
principalJTextField.setBounds(100, 16, 100, 24);
principalJTextField.setHorizontalAlignment(JTextField.RIGHT);
contentPane.add(principalJTextField);
// set up interestRateJLabel
interestRateJLabel = new JLabel();
interestRateJLabel.setBounds(16, 56, 80, 24);
interestRateJLabel.setText("Interest rate:");
contentPane.add(interestRateJLabel);
// set up interestRateJTextField
interestRateJTextField = new JTextField();
interestRateJTextField.setBounds(100, 56, 100, 24);
interestRateJTextField.setHorizontalAlignment(JTextField.RIGHT);
contentPane.add(interestRateJTextField);
// set up yearsJLabel
yearsJLabel = new JLabel();
yearsJLabel.setBounds(16, 96, 48, 24);
yearsJLabel.setText("Years:");
contentPane.add(yearsJLabel);
// set up yearsJSpinner
yearsJSpinner = new JSpinner(new SpinnerNumberModel(1, 1, 10, 1));
yearsJSpinner.setBounds(100, 96, 100, 24);
contentPane.add(yearsJSpinner);
// set up yearlyBalanceJLabel
yearlyBalanceJLabel = new JLabel();
yearlyBalanceJLabel.setBounds(16, 136, 150, 24);
yearlyBalanceJLabel.setText("Yearly account balance:");
contentPane.add(yearlyBalanceJLabel);
// set up yearlyBalanceJTextArea
yearlyBalanceJTextArea = new JTextArea();
yearlyBalanceJTextArea.setEditable(false);
// set up yearlyBalanceJScrollPane
yearlyBalanceJScrollPane = new JScrollPane(yearlyBalanceJTextArea);
yearlyBalanceJScrollPane.setBounds(16, 160, 300, 92);
contentPane.add(yearlyBalanceJScrollPane);
// set up calculateJButton
calculateJButton = new JButton();
calculateJButton.setBounds(216, 16, 100, 24);
calculateJButton.setText("Calculate");
contentPane.add(calculateJButton);
calculateJButton.addActionListener(
new ActionListener() // anonymous inner class
{
// event handler called when calculateJButton is clicked
public void actionPerformed(ActionEvent event) {
calculateJButtonActionPerformed(event);
}
} // end anonymous inner class
); // end call to addActionListener
// set properties of application's window
setTitle("Interest Calculator"); // set title bar text
setSize(340, 296); // set window size
setVisible(true); // display window
} // end method createUserInterface