import java.awt.*;
import java.awt.event.*;			// for ActionListener, MouseListener
import javax.swing.*;

public class SimpleMouseExample		// used to draw lines between point where mouse is pressed and point where mouse is released
{
	public static void main(String[] args)
	{
		JFrame frame=new JFrame("simple button example");
		frame.setSize(500,500);
		MouseExample p=new MouseExample();
		frame.add(p);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setVisible(true);
	}
	
	public static class MouseExample extends JPanel implements ActionListener, MouseListener	// ActionListener for 1 JButton
	{
		private int x1, y1, x2, y2;			// X,Y coordinate of latest Mouse Event
		private boolean clear;				// boolean used to determine whether to clear the Graphics object or not
		
		public MouseExample()				
		{
			x1=x2=y1=y2=-1;					// no current coordinate, set it to some off-the-screen value
			JButton reset=new JButton("Reset Drawing");	// JButton to change clear from false to true to clear the Graphics object
			reset.addActionListener(this);	// use this class to implement this JButton's ActionListener
			add(reset);						// add the JButton to this JPanel
			addMouseListener(this);			// add a MouseListener to this class
			clear=false;					// clear indicates whether the reset the Graphics object, currently false
		}
		
		public void actionPerformed(ActionEvent e)
		{
			clear=true;						// upon JButton click, reset clear to true and repaint
			repaint();
		}
		
		public void mouseClicked(MouseEvent e) {}	// we only need to implement mousePressed and mouseReleased, these others
		public void mouseEntered(MouseEvent e) {}	// have to be here to implement MouseListener but we don't need code for them
		public void mouseExited(MouseEvent e) {}

		public void mousePressed(MouseEvent e) 	// upon mousePressed, remember the x,y coordinate which will be the start of our line
		{
			x1=e.getX();
			y1=e.getY();
		}
		
		public void mouseReleased(MouseEvent e) // upon mouseReleased, get the x,y coordinate and call repaint to draw a line
		{										// from x,y coordinates when mousePressed to these x,y coordinates
			x2=e.getX();
			y2=e.getY();
			repaint();
		}
		
		public void paintComponent(Graphics g)	// either clear the Graphics image (super.paintComponent(g)) or draw a line
		{
			if(clear)							// upon clear, clear the Graphics image and reset clear to false
			{
				clear=false;
				super.paintComponent(g);
			}
			else g.drawLine(x1,y1,x2,y2);		// upon !clear, draw the line
		}
	}
}