During my searching, I would like to have some help about my problem :
So this is my error, the trace :
Normally the class User.java works.
This is a piece of my class java (User.java) that corresponds to my error :
My variable service corresponds at a line of a result at my database.
I think my row is NULL in the database (because a nullPointerException is mainly that ... an object set at NULL !) but I don't know to solve the problem in my database : to change value in the row of my database.