DrawLine.java

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

public class DrawLine extends JFrame{    
    public DrawLine(){        
        PaintCanvas pc=new PaintCanvas();
        getContentPane().add(pc);
    }     
    class PaintCanvas extends Canvas implements MouseMotionListener,MouseListener{
 		// ekranda çizilecek çizginin başlangıç ve bitiş bilgilerini tutan değişkenler.
        int x1,y1,x2,y2;
        public void paint(Graphics g){
            g.drawLine(x1,y1,x2,y2);
            addMouseListener(this);
            addMouseMotionListener(this);
        }        
        public void mouseDragged(MouseEvent e){
            x2=e.getX();
            y2=e.getY();
 		    // ekranın yeniden çizilmesi için repaint çağrılır	
            repaint();
        }        
        public void mouseMoved(MouseEvent e){}        
        public void mousePressed(MouseEvent e){
            x1=e.getX();
            y1=e.getY();
        }          
        public void mouseClicked(MouseEvent e){}
        public void mouseEntered(MouseEvent e){}       
        public void mouseExited(MouseEvent e){}             
        public void mouseReleased(MouseEvent e){}
    }     
    public static void main(String[] args){
       DrawLine dl=new DrawLine();
       dl.setBounds(0,0,300,300);
       dl.setVisible(true);
    }    
}