// WindowPractice1.java
// Practice with anonymous inner classes, JFrame, windows, WindowAdapter
import java.text.DecimalFormat;
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;

public class WindowPractice1 extends JFrame {
	DecimalFormat precision2 = new DecimalFormat( "0.00" );

	private double length, width;
	private JLabel lengthLabel, widthLabel, areaLabel;
	private JTextField lengthField, widthField, areaField;

	// constructor
	public WindowPractice1( ) {
		super ( "Anonymous Inner Class Practice" );

		Container c = getContentPane( );

		c.setLayout( new FlowLayout( ) );
		lengthLabel = new JLabel( "Enter the length:" );
		lengthField = new JTextField( 10 );

		lengthField.addActionListener( 
			new ActionListener( ) {  // anonymous inner class begins
				public void actionPerformed( ActionEvent e ) {
					calcArea( );
				}
			}  // anonymous inner class ends
		);
		c.add( lengthLabel );
		c.add( lengthField );

		widthLabel = new JLabel( "Enter the width:" );
		widthField = new JTextField( 10 );

		widthField.addActionListener( 
			new ActionListener( ) {  // anonymous inner class begins
				public void actionPerformed( ActionEvent e ) {
					calcArea( );
				}
			}  // anonymous inner class ends
		);

		c.add( widthLabel );
		c.add( widthField );

		areaLabel = new JLabel( "Area of the rectangle" );
		areaField = new JTextField( 10 );
		areaField.setEditable( false );
		c.add( areaLabel );
		c.add( areaField );
	}
		
	public void calcArea( ) {
		length = Double.parseDouble( lengthField.getText( ) );
		width = Double.parseDouble( widthField.getText( ) );
		areaField.setText( precision2.format( length * width ) );
	}

	public static void main( String args[ ] ) {
		WindowPractice1 w = new WindowPractice1( );

		w.addWindowListener( 
			new WindowAdapter( ) {  // anonymous inner class begins
				public void windowClosing( WindowEvent e ) {
					System.exit( 0 );
				}
			}  // anonymous inner class ends
		);

		w.setSize( 300, 150 );
		w.show( );
	}
}