// The Calculator example implemented as a GUI application.

import java.awt.*;
import java.awt.event.*;

class Calculator extends Frame implements ActionListener {

   float number1, number2, result;
   Label label1, label2, label3, title;
   TextField input1, input2, input3;
   String operation;

   // Constructor for the Calculator class

   public Calculator () {

     setLayout (new FlowLayout ());
   
     title = new Label ("Calculator program");

     label1 = new Label ("Enter the first number: ");
     label2 = new Label ("Enter the second number: ");
     label3 = new Label ("Enter the operation (+, -, *, or /): ");

     input1 = new TextField (8);
     input2 = new TextField (8);
     input3 = new TextField (1);

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

     number1 = 0;
     number2 = 0;
     operation = "";
   }

   public void paint (Graphics g) {

    if (operation.equals (""));
    else if ((operation.equals ("/")) & (number2 == 0))
       g.drawString ("Division by zero is not permitted", 10, 250);
       else
          g.drawString (number1 + " " + operation + " " + number2 + " = " + result, 30, 250);

   }

   public void actionPerformed (ActionEvent e) {

     number1 = Float.parseFloat(input1.getText());
     number2 = Float.parseFloat(input2.getText());
     operation = input3.getText();

     if (operation.equals ("+"))
        result = number1 + number2;
     else if (operation.equals ("-"))
        result = number1 - number2;
     else if (operation.equals ("*"))
        result = number1 * number2;
     else {
        if (number2 == 0);
        else
           result = number1 / number2;
     }
        
     repaint();
   }

}

class CalculatorGUI1 {


   public static void main (String[] args) {

   Calculator calculator = new Calculator ();
   calculator.setSize(200, 400);
   calculator.setVisible(true);
   }
}