Sample: investment

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import javax.swing.border.*;

public class Investment extends JFrame {

  private JTextField jtfInvestmentAmount;

  private JTextField jtfYears;

  private JTextField jtfInterestRate;

  private JTextField jtfFutureValue;

  private JButton jbtCalculate;

  public static void main(String[] args) {

    JFrame frame = new  Investment();

    frame.pack();

    frame.setTitle("Investment");

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.setLocationRelativeTo(null); // Center the frame

    frame.setVisible(true);

  }

  public  Investment() {

    // Create a new panel with GridLayout to hold labels and text boxes

    JPanel p = new JPanel();

    p.setLayout(new GridLayout(4, 2, 5, 0));

    p.setBorder(new EmptyBorder(5, 5, 5, 5));

    p.add(new JLabel("Investment Amount"));

    p.add(jtfInvestmentAmount = new JTextField(8));

    p.add(new JLabel("Years"));

    p.add(jtfYears = new JTextField(8));

    p.add(new JLabel("Annual Interest Rate"));

    p.add(jtfInterestRate = new JTextField(8));

    p.add(new JLabel("Future value"));

    p.add(jtfFutureValue = new JTextField(8));

    jtfFutureValue.setEditable(false);

    // Add the panel and a button to the frame

    setLayout(new BorderLayout());

    add(p, BorderLayout.CENTER);

    // Add a button to a panel

    JPanel p1 = new JPanel(new FlowLayout(FlowLayout.RIGHT));

    p1.add(jbtCalculate = new JButton("Calculate"));

    add(p1, BorderLayout.SOUTH);

    jbtCalculate.setMnemonic('C');

    jtfInvestmentAmount.setHorizontalAlignment(JTextField.RIGHT);

    jtfYears.setHorizontalAlignment(JTextField.RIGHT);

    jtfInterestRate.setHorizontalAlignment(JTextField.RIGHT);

    jtfFutureValue.setHorizontalAlignment(JTextField.RIGHT);

    // Register listener

    jbtCalculate.addActionListener(new ActionListener() {

      // Handle ActionEvent

      public void actionPerformed(ActionEvent e) {

        calculate();

      }

    });

  }

  // Calculate future value

  public void calculate() {

    double investmentAmount =

      Double.valueOf(jtfInvestmentAmount.getText().trim()).

      doubleValue();

    int years =

      Integer.valueOf(jtfYears.getText().trim()).intValue();

    double interestRate = Double.valueOf(jtfInterestRate.getText().

      trim()).doubleValue();

    double futureValue = investmentAmount * Math.pow((1 +

      interestRate / (12 * 100)), 12 * years);

//    NumberFormat nf = NumberFormat.getCurrencyInstance(Locale.US);

//    jtfFutureValue.setText(nf.format(futureValue));

    jtfFutureValue.setText((int)(futureValue * 100) / 100.0 + "");

  }

}