//Given the length and width of a rectangle, this Java
//program determines its area and perimeter.

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

public class RectangleProgram extends JFrame
{
    JLabel lengthL, widthL,
           areaL, perimeterL;
    JTextField lengthTF, widthTF,
		           areaTF, perimeterTF;
    JButton calculateB, exitB;
    CalculateButtonHandler calculateHandler;
    ExitButtonHandler exitHandler;

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

    public RectangleProgram()
    {
		        // Create four labels
	      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);

		          //Create four textfields
	      lengthTF = new JTextField(10);
	      widthTF = new JTextField(10);
	      areaTF = new JTextField(10);
	      perimeterTF = new JTextField(10);

		          //create Calculate Button
	      calculateB = new JButton("Calculate");
	      calculateHandler = new CalculateButtonHandler();
	      calculateB.addActionListener(calculateHandler);

		          //Create Exit Button
	      exitB = new JButton("Exit");
	      exitHandler = new ExitButtonHandler();
	      exitB.addActionListener(exitHandler);

		          //Set the title of the window
	      setTitle("Area and Perimeter of a Rectangle");

		          //Get the container
	      Container pane = getContentPane();

		          //Set the layout
        pane.setLayout(new GridLayout(5,2));

		          //Place all items created
	      pane.add(lengthL);
	      pane.add(lengthTF);
	      pane.add(widthL);
	      pane.add(widthTF);
	      pane.add(areaL);
	      pane.add(areaTF);
	      pane.add(perimeterL);
	      pane.add(perimeterTF);
	      pane.add(calculateB);
	      pane.add(exitB);

		        //set the size of the window and display it
	      setSize(WIDTH,HEIGHT);
	      setVisible(true);
			  setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    private class CalculateButtonHandler implements ActionListener
    {
	      public void actionPerformed(ActionEvent e)
	      {
	          double width, length, area, perimeter;

	          length = Double.parseDouble(lengthTF.getText());
	          width = Double.parseDouble(widthTF.getText());
	          area = length * width;
	          perimeter = 2 * (length + width);

	          areaTF.setText("" + area);
	          perimeterTF.setText("" + perimeter);
	      }
    }

    private class ExitButtonHandler implements ActionListener
    {
	      public void actionPerformed(ActionEvent e)
	      {
		        System.exit(0);
	      }
    }

    public static void main( String args[] )
    {
	        RectangleProgram rectObject = new RectangleProgram();
    }
}