What is the difference between EntityManager.find() and EntityManger.getReference()?

Question

Whats is the difference between

 T EntityManager.find(Class entityClass, Object primaryKey) and 
 T EntityManager.getReference(Cl         


        

Answer 1

The book Beginning Java EE 6 Platform with GlassFish 3, mention the differences in page 135: "Finding By ID"

find() if the entity is found, it is returned; if it is not found, a null value is returned.

MyEntity obj = em.find(MyEntity.class, id);
if(obj != null){
   // Process the object 
}

getReference() is intended for situations where a managed entity instance is needed, but no data, other than potentially the entity's primary key, being accessed.

try {
    MyEntity obj = em.getReference(MyEntity.class, id);
    // Process the object
} catch (EntityNotFoundException e) {
    // Entity Not Found
}