JavaElementVisitor in PSI - how can I use it?

I am looking for a way to get the concrete type of a PsiElement - something like JavaElementVisitor. But I coundn't find any way to use JavaElementVisitor or to expose the type of a PsiElement.

I saw an old code using PsiElementVisitor with a lot of methods. But the exposed PSI PsiElementVisitor contains only one method, that is not very useful.

For short, how can I even start using PsiElement? Without a type info of a visitor, it is rather Opaque.

Thanks in advance.