What are user-defined data types in Java?

Question

variables declared using class type are user-defined.

But I am not convinced with my answer. I feel class type is Reference data type/Object data type.

As per there are two types:
Primitive data types [int,float..etc].
Reference type/Object type[String str, user_defined_Class Obj1..etc]

I did search on this, but couldn't get a proper answer.
Kindly shed some light on this.

Answer 1

nobody can define primitive types
types declared in API are not called 'user defined', they are type of Object / reference type, eg ArrayList
users can define user type of object by user defined class