// Fig. 20.10: AdditionApplet.java
// Adding two floating-point numbers.
import java.awt.Graphics;       // program uses class Graphics
import javax.swing.JApplet;     // program uses class JApplet
import javax.swing.JOptionPane; // program uses class JOptionPane

public class AdditionApplet extends JApplet 
{
   private double sum; // sum of values entered by user

   // initialize applet by obtaining values from user
   public void init()
   {
      String firstNumber;  // first string entered by user
      String secondNumber; // second string entered by user

      double number1; // first number to add
      double number2; // second number to add

      // obtain first number from user
      firstNumber = JOptionPane.showInputDialog(
         "Enter first floating-point value" );

      // obtain second number from user
      secondNumber = JOptionPane.showInputDialog(
         "Enter second floating-point value" );

      // convert numbers from type String to type double
      number1 = Double.parseDouble( firstNumber ); 
      number2 = Double.parseDouble( secondNumber );

      sum = number1 + number2; // add numbers
   } // end method init

   // draw results in a rectangle on applet’s background
   public void paint( Graphics g )
   {
      super.paint( g ); // call superclass version of method paint

      // draw rectangle starting from (15, 10) that is 270 
      // pixels wide and 20 pixels tall
      g.drawRect( 15, 10, 270, 20 );

      // draw results as a String at (25, 25)
      g.drawString( "The sum is " + sum, 25, 25 );
   } // end method paint
} // end class AdditionApplet

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