public void paintComponent(Graphics g){
  g.setColor(getBackground());
  g.fillRect(0,0,getWidth(),getHeight());
  g.setColor(currentColor);
  g.fillOval(0,0,getWidth(),getHeight());
}

public void paintComponent ( Graphics g ) { g . setColor ( getBackground ( ) ) ; g . fillRect ( 0 , 0 , getWidth ( ) , getHeight ( ) ) ; g . setColor ( currentColor ) ; g . fillOval ( 0 , 0 , getWidth ( ) , getHeight ( ) ) ; }
erase to the background color and fill an oval with the current color ( which is being animated elsewhere )
