public void keyPressed(KeyEvent e){
  if (isNavigationKey(e)) {
    prefix="";
    typedString="";
    lastTime=0L;
  }
}

public void keyPressed ( KeyEvent e ) { if ( isNavigationKey ( e ) ) { prefix = "" ; typedString = "" ; lastTime = 0L ; } }
invoked when a key has been pressed . checks to see if the key event is a navigation key to prevent dispatching these keys for the first letter navigation .
