What states can an object have in Hibernate?

In Hibernate, an object can be in one of the following states:

• Transient: The object is created using the new operator but is not yet associated with a Hibernate session. It has no corresponding record in the database.

  // Transient state  
  User user = new User();  
  user.setName("John Doe");  
  

• Persistent: The object is associated with an active Hibernate session. Any changes made to the object will be synchronized with the database upon transaction commit or flush. It has a corresponding row in the database.

  // Transition from Transient to Persistent  
  session.save(user);  
  

  Changes in a Persistent object are tracked:

  // Modification of a Persistent object  
  user.setEmail("john.doe@example.com"); // Changes will be persisted  
  

• Detached: The object was previously Persistent, but its session was closed or the object was explicitly detached (session.evict(object)). It is not associated with an active session, and changes will not be automatically synchronized with the database.

  // Transition from Persistent to Detached  
  session.close(); // Or session.evict(user);  
  

  To save changes to a Detached object, it must be reattached to a session:

  // Reattaching a Detached object  
  session.update(user); // Or session.merge(user);  
  

Summary table of states:

State	Session association	Database correspondence	Change tracking	How to obtain/transition
Transient	No	No	No	new YourClass()
Persistent	Yes	Yes	Yes	session.save(), session.get(), session.load(), session.createQuery().list()
Detached	No	Yes	No	session.close(), session.evict(), session.clear()