What is a practical use of an inner class?

Answer 1

I think usually some kind of helper or event handling class. You might have to do some practical tutorials on a subject to see some useful examples.

Answer 2

encapsulation. if you have a computer class with several private nested classes (ie. processor, ram, soundCard etc) then only the computer class needs to use/see the nested ones. your car class probably doesn't need to see the soundCard class.