private boolean nameInUse() {
        if (tfFirstName.getText().isEmpty() || tfFamilyName.getText().isEmpty()) {
            lblNameInUse.setVisible(false);
            return true;
        } else {
            String firstName = tfFirstName.getText();
            String familyName = tfFamilyName.getText();
            Employee existingEmployee = RoosterProgramma.getInstance().getEmployee(firstName, "", familyName);
            if (existingEmployee != null
                    && (isAdd
                    || existingEmployee.getEmployeeNumber() != employee.getEmployeeNumber())) {
                lblNameInUse.setVisible(true);
                return true;
            } else {
                lblNameInUse.setVisible(false);
                return false;
            }
        }
    }