GRAPHICAL USER INTERFACE (GUI) AND OBJECT-ORIENTED DESIGN (OOD) - Java Programming: From Problem Analysis to Program Design - page 342

RectangleProgramOne of the preceding section and, like RectangleProgramOne ,isa
subclass of JFrame .

//Java program to create a window and place four labels

import javax.swing.*;
import java.awt.*;

public class RectangleProgramTwo extends JFrame
{

private static final int WIDTH = 400;
private static final int HEIGHT = 300;

private JLabel lengthL, widthL, areaL, perimeterL;

public RectangleProgramTwo()
{

setTitle("Area and Perimeter of a Rectangle");

lengthL =
new JLabel("Enter the length: ", SwingConstants.RIGHT);
widthL =
new JLabel("Enter the width: ", SwingConstants.RIGHT);
areaL = new JLabel("Area: ", SwingConstants.RIGHT);
perimeterL =
new JLabel("Perimeter: ", SwingConstants.RIGHT);

Container pane = getContentPane();
pane.setLayout( new GridLayout(4, 1));

pane.add(lengthL);
pane.add(widthL);
pane.add(areaL);
pane.add(perimeterL);

setSize(WIDTH, HEIGHT);
setVisible( true );
setDefaultCloseOperation(EXIT_ON_CLOSE);

}

public static void main(String[] args)
{

RectangleProgramTwo rectObject = new RectangleProgramTwo();

}

}