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

class Program01 {
	public static void main ( String[] args ) {
		JFrame paint = new JFrame ();

		paint.add ( new JComponent () {
			private ArrayList<Shape> shapes = new ArrayList<Shape>();
			private Shape currentShape = null;

			{
				MouseAdapter mouseAdapter = new MouseAdapter () {
					public void mousePressed ( MouseEvent e ) {
						currentShape = new Line2D.Double ( 
							e.getPoint (), e.getPoint () );
						shapes.add ( currentShape );
						repaint ();
					}
					public void mouseReleased ( MouseEvent e ) {
						currentShape = null;
						repaint ();
					}
					public void mouseDragged ( MouseEvent e ) {
						Line2D shape = ( Line2D ) currentShape;
						shape.setLine ( shape.getP1 (), e.getPoint () );
						repaint ();
					}
				};
				addMouseListener ( mouseAdapter );
				addMouseMotionListener ( mouseAdapter );
			}

			protected void paintComponent ( Graphics g ) {
				Graphics2D g2d = ( Graphics2D ) g;
				g2d.setPaint ( Color.BLACK );

				for ( Shape shape : shapes ) {
					g2d.draw ( shape );
				}
			}
		} );

		paint.setSize ( 500, 500 );
		paint.setLocationRelativeTo ( null );
		paint.setVisible ( true );
	}

}