public JRadioButtonBinding(String property, JRadioButton[] buttons, int defaultValue) {
		if (property == null || buttons == null) {
			throw new NullPointerException();
		}
		for (int i = 0; i < buttons.length; i++) {
			if (buttons[i] == null) {
				throw new NullPointerException();
			}
		}
		if (property.equals("")
				|| buttons.length == 0
				|| defaultValue < 0 || defaultValue >= buttons.length) {
			throw new IllegalArgumentException();
		}
		_property = property;
		_buttons = buttons;
		_defaultValue = defaultValue;
		_validColor = buttons[0].getBackground();
	}