Dear Mr. Peter,
Really many thanks for your help,
This a first time for working with Pi4J, and sure I'll need long time to work well with it, (by any way i try more with it).
But the capabilities of programming (by b4a) with mobile are very very good, many libraires (like what work with DB, graphics, .....),
and to reach for same level/capabilities with Pi4J take from me very long time.
So, I need now to use all libraries, examples, ... of b4a direct with Raspberry Pi (if I good understanding, and please correct me if it is not right).
thanks again for you.