AdditionApplet.java
// Fig. 3.13: AdditionApplet.java
// Adding two floating-point numbers.
// Java packages
import java.awt.Graphics; // import class Graphics
import javax.swing.*; // import package javax.swing
public class AdditionApplet extends JApplet {
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 );
// add numbers
sum = number1 + number2;
} // end method init
// draw results in a rectangle on applet background
public void paint( Graphics g )
{
// call superclass version of method paint
super.paint( g );
// 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