Example & Tutorial understanding programming in easy ways.

Associations are used to represent relationships between classes.  Managed association means that, if a change is made to one end of the association, it will be reflected at the other end. So when changes are made to the attributes participating in this association, they will be reflected at the other end automatically. The developer doesn’t have to mange the associations manually. 

Hibernate mainly supports two types of associations:

  1. One-to-Many

  2. Many-to-One

Managed Association: Basically association are used to represent relationship between class. Managed Association means that, if a change is made to one end to the association, it will be relected at the other end. So when changes are made to the attributes participating in this association, they will be reflected at the end automatically. The developer does not have manage association manually. 

Hibernate mainly supports two type of association those are:

Hibernate Association: If any table i db could be connected to other tables in same or other DB and these tables could be associated with each other by some key. Those kind of scenario can be handled with association.

Example: There are two table in DB, Student  & Subject. A student can study one subject or more then one subject. In that case every student will have only one entry in Student table but Subject table could contain more than one record for corresponding record in Student table.

Association mapping are used to map a java object to DB table.

Rules for association with POJO class:

pojo class need to have default constructor as it is required by Hibernate.

Lazy loading does not work with final class.its preferable to have Non Final classes.

Undirectional Association with join table;