>> 462
こんなんでいいのかな？
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
/*
<applet code="a" width=320 height=240></applet>
*/
public class a extends Applet{
Point[] p = new Point[2];
Color c = new Color(255,255,0);

public void init(){
setBackground(c);
addMouseListener(new MouseAdapter(){
public void mousePressed(MouseEvent me){
p[0] = me.getPoint();
setBackground(c);
}
public void mouseReleased(MouseEvent me){
p[0] = null;
repaint();
}
});
addMouseMotionListener(new MouseMotionAdapter(){
public void mouseDragged(MouseEvent me){
p[1] = me.getPoint();
repaint();
}
});
}

public void paint(Graphics unko){
int a,b,c,d;
int i,r;
if( p[0] != null && p[1] != null){
a=(int)p[0].getX();
b=(int)p[1].getX();
c=(int)p[0].getY();
d=(int)p[1].getY();
r = (int)Math.sqrt((double)((a-b)*(a-b)+(c-d)*(c-d)));
unko.drawOval(a+r, c+r, r, r);
}
}
}