The first approach we will discuss is including the authorization logic in the UI components themselves. This is what we have done in the example application, where we show a PrivateComponent if the user is authenticated or a PublicComponent if they are not. You can extrapolate this and use it with, for example, roles. Suppose there were two roles: employee and admin. You have to show a hypothetical AdminComponent to users with the role admin and an EmployeeComponent to users with the employee role. You can easily code a method that returns the right component according to the role as follows:
private Optional<Component> getComponent(User user) {
if (user.getRole().equals(Role.Admin)) {
return new ...
