Is Energy proptional to frequency(standing wave)

Here is an extract from my Physics textbook.

According to classical physics, each of these standing waves carries energy, and as their frequency increases, so does their energy .

I don't understand how this is true .

I think that the classical wave theory says that the energy is proportional to the intensity while on the other hand it is the Quantum theory which predicts :

E = [itex]h[/itex] f

So, is there an error in the book regarding this issue ?