Simple Interest Calculator Java Applet

A sample interest calculator, very basic in functionality, coded in Java and ready to be compiled and executed as a Java Applet.

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.text.NumberFormat;

public class InterestCalculator extends Applet implements ActionListener 

       TextField textPresentVal = new TextField("0", 10);
       TextField textInterestRate = new TextField("0", 10);
        TextField textPeriods = new TextField("0", 10);
        Label lblPresentVal = new Label("Present Value");
        Label lblInterestRate = new Label("Interest Rate");
        Label lblPeriods = new Label("Number of Periods");
        Label lblFutureVal = new Label("Future Value:");
        Button btnOk = new Button("Calculate");
 
        public void init()
        {
 
                add(lblPresentVal);
                add(textPresentVal);
                add(lblInterestRate);
                add(textInterestRate);
                add(lblPeriods);
                add(textPeriods);
                add(lblFutureVal);
                add(btnOk);
 
                btnOk.addActionListener(this);
        }
 
        public void actionPerformed(ActionEvent evt)  
        {
            if (evt.getSource() == btnOk)
            {
                int PresentVal = Integer.parseInt(textPresentVal.getText());
                int InterestRate = Integer.parseInt(textInterestRate.getText());
                int Periods = Integer.parseInt(textPeriods.getText());
                double FutureVal = PresentVal * (Math.pow((1 + InterestRate), Periods));
                NumberFormat nf = NumberFormat.getCurrencyInstance();
                lblTotal.setText("Future Value: " + nf.format(FutureVal));
 
                repaint();
            }
        }
}