Java Code

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TextChange extends JApplet implements FocusListener
{
	JLabel status;	// starts out empty, displays error messages
	JTextField email;
	JTextArea mesg;
	JScrollPane scroll;
	public void init( )
	{
		setLayout( new FlowLayout( ) );
		status = new JLabel( );
		status.setForeground( Color.RED );
		email = new JTextField(15);
		mesg = new JTextArea( 4, 10 );
		scroll = new JScrollPane( mesg );
		email.addFocusListener( this );
		mesg.addFocusListener( this );
		add( email );
		add( scroll );
		add( status );
	}
	public void focusGained( FocusEvent fe ) { } // method stub
	public void focusLost( FocusEvent fe )
	{
		Object src = fe.getSource( );
		if ( src == email )
		{
			String userText = email.getText( );
			if ( ! userText.contains( "@" ) )
				status.setText( "Must provide a valid email address." );
			else
				status.setText( "" );  // everything is fine
		}
		else if ( src == mesg )
		{
			String mesgText = mesg.getText( );
			if ( mesgText.length( ) < 1 )
				status.setText( "Must provide a message" );
			else
				status.setText( "" );  // everything is fine
		}
	}
}