code: public void caretUpdate(CaretEvent event) {
  		String text = getText().trim();
  		String emptyMask = maskPattern.replace('#', placeholder);
  
  		if (text.length() == 0 || text.equals(emptyMask)) {
  			setForeground(Color.BLACK);
  			return;
  		}
  
  		try {
  			Date date = dateFormatter.parse(getText());
  			if (dateUtil.checkDate(date)) {
  				setForeground(darkGreen);
  			} else {
  				setForeground(Color.RED);
  			}
  		} catch (Exception e) {
  			setForeground(Color.RED);
  		}
  	}
docs: After any user input, the value of the textfield is proofed. Depending on
  being a valid date, the value is colored green or red.
  
  @param event
  the caret event