Java sample(BarGraph & MouseDrag)

//Example06
import java.awt.*;
import java.awt.event.*;
public class Example06 extends Frame implements MouseListener, MouseMotionListener{
  TextField[] tf=new TextField[2];
  static int x1=303,y1=198,x2=343,y2=198,sw=0;
  //Main
  public static void main(String ar[]){
    Frame f=new Example06();
    f.setTitle("BarGraph & MouseDragg");
    f.setSize(640,400);
    f.setVisible(true);
  }
  //Frame
  Example06(){
    int i;
    setLayout(new FlowLayout());
    for(i=0;i<2;i++){
      tf[i]=new TextField("100",3);
      add(tf[i]);
    }
    addMouseListener(this);
    addMouseMotionListener(this);
    addWindowListener(new WinAdapter());
  }
  //Close
  class WinAdapter extends WindowAdapter{
    public void windowClosing(WindowEvent we){System.exit(0);}
  }
  //Paint
  public void paint(Graphics g){
    String rs;
    int hei;
    int i;
    int r=2;
    g.clearRect(0,0,639,399);
    for(i=0;i<2;i++){
      rs = tf[i].getText();
      if (rs != null) {
        try {
          hei=Integer.parseInt(rs);
          g.setColor(Color.blue);
          g.fillRect(300+i*40,300-hei,10,hei);
          g.setColor(Color.red);
          g.fillOval(305+i*40-r,300-hei-r,2*r,2*r);
          if (i==0) y1=300-hei-r;
          if (i==1) y2=300-hei-r;
        } catch (NumberFormatException e) {}
      }
    }
  }
  public void mousePressed(MouseEvent me){
    int x,y;
    sw=0;
    x=me.getX();
    y=me.getY();
    if (Math.abs(x1-x)<3 && Math.abs(y1-y)<3){
      sw=1;
      setCursor(Cursor.getPredefinedCursor(HAND_CURSOR));
    }
    if (Math.abs(x2-x)<3 && Math.abs(y2-y)<3){
      sw=2;
      setCursor(Cursor.getPredefinedCursor(HAND_CURSOR));
    }
  }
  public void mouseDragged(MouseEvent me){
    int y;
    if (sw>0){
      y=me.getY();
      tf[sw-1].setText(""+(298-y));
      repaint();
    }
  }
  public void mouseReleased(MouseEvent me){
    setCursor(Cursor.getPredefinedCursor(DEFAULT_CURSOR));
  }
  public void mouseMoved(MouseEvent me){}
  public void mouseEntered(MouseEvent me){}
  public void mouseExited(MouseEvent me){}
  public void mouseClicked(MouseEvent me){}
}