Question

Conider I have a Class called Entity that has 3 children :
ClientEntity, EmployeeEntity and ProductEntity
I want to have a static attribute _nextId (that gives the new id for a new record)
_nextId has a different value in each entity, but its a common attribute to all Entity children.

So my question is how can I put _nextId in Entity class and have methods that change this value, while getting a different value for each child class.

Thank you.

Answer 1

Assuming Entity is abstract, you could create a :

protected abstract getNextId();

method which each concrete subclass will need to implement. That implementation can for example rely on a static counter.