/* Example to illustrate the ActionListener interface: write an applet to 
compute the balance of an investment specified by the user, for a period 
of time and rate also specified by the user. The formula for computing
the balance is principal * (1 + rate) ^ years. Adapted from Deitel & Deitel */

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

public class Balance extends Applet implements ActionListener {

   double balance, principal, rate;
   int years;
   Label label1, label2, label3, title;
   TextField input1, input2, input3;

   public void init () {
   
     title = new Label ("Balance calculator");

     label1 = new Label ("Enter principal: ");
     label2 = new Label ("Enter rate: ");
     label3 = new Label ("Enter period of time (in years): ");

     input1 = new TextField (8);
     input2 = new TextField (8);
     input3 = new TextField (8);

     add (title);
     add (label1);
     add (input1);
     add (label2);
     add (input2);
     add (label3);
     add (input3);    
     input3.addActionListener(this);

     balance = 0;
     rate = 0;
     years = 0;
   }

   public void paint ( Graphics g ) {
   
      int yPos = 240;
      DecimalFormat precisionTwo = new DecimalFormat( "#.00" );

      g.drawString( "Year", 25, 185 );
      g.drawString( "Amount on deposit", 100, 185 );
 
      for ( int year = 1; year <= years; year++ ) {
         balance = principal * Math.pow( 1.0 + rate, year );
         g.drawString( Integer.toString( year ), 25, yPos );
         g.drawString( precisionTwo.format(balance), 100, yPos );
         yPos += 15;
      }
   }

   public void actionPerformed (ActionEvent e) {

     principal = new Double (input1.getText()).doubleValue();
     rate = new Double (input2.getText()).doubleValue();
     years = Integer.parseInt(input3.getText());
        
     repaint();
   }
}