DrawLineCanvas.java

package com.godoro.samples.awt;

import java.awt.*;
import java.awt.event.*;

public class DrawLineCanvas extends Canvas
{
  private int x1;
  private int y1;
  private int x2;
  private int y2;

  public DrawLineCanvas()
  {
    MouseAdapter mouse=new MouseAdapter(){
      public void mousePressed(MouseEvent e){
        x1 = e.getX();
        y1 = e.getY();
      }  
    };
    addMouseListener(mouse);
    MouseMotionAdapter motion = new MouseMotionAdapter(){
      public void mouseDragged(MouseEvent e){
        x2 = e.getX();
        y2 = e.getY();
        repaint();
      }
    };
    addMouseMotionListener(motion);
  }
  public void paint(Graphics g){
    g.drawLine(x1, y1, x2, y2);
  }
  public static void main(String[] args){
    Frame frame = new Frame();
    frame.setBounds(0, 0, 300, 300);
    DrawLineCanvas canvas = new DrawLineCanvas();
    frame.add(canvas);
    frame.setVisible(true);
  }
}