Charging and listening...can it be done?

I bought a generic wall charger at the store that uses a USB plug in.  It did not come with a USB plug, I use the Fuze one.  I can chage and listen to at the same time.  This also came with a car charger that plugs into the USB cord and car, which means I can charge it while driving and listen to it in my car (I use a cassette adaptor).