How to get all nonprimitive types that are visible in a java class?

Hello everyone,

can anyone help me out on finding all nonprimitive types known in PsiClass? That means types like String, Interger, Math and types of classes in the same package and even the types that are not imported like types form other packages or types from packages like Java.Util. I get textual input that could contain types and need to recognize it as a type

Thank you in advance I'm very grateful for any help.

Best regards!