find(entityClass, primaryKey, lockMode, properties) - JPA EntityManager's method

T find(
  Class<T> entityClass,
  Object primaryKey,
  LockModeType lockMode,
  Map<K,V> properties

Find by primary key and lock, using the specified properties. Search for an entity of the specified class and primary key and lock it with respect to the specified lock type. If the entity instance is contained in the persistence context, it is returned from there.

If the entity is found within the persistence context and the lock mode type is pessimistic and the entity has a version attribute, the persistence provider must perform optimistic version checks when obtaining the database lock. If these checks fail, the OptimisticLockException will be thrown.

If the lock mode type is pessimistic and the entity instance is found but cannot be locked:

  • the PessimisticLockException will be thrown if the database locking failure causes transaction-level rollback
  • the LockTimeoutException will be thrown if the database locking failure causes only statement-level rollback

If a vendor-specific property or hint is not recognized, it is silently ignored.

Portable applications should not rely on the standard timeout hint. Depending on the database in use and the locking mechanisms used by the provider, the hint may or may not be observed.

entityClass - entity class
primaryKey - primary key
lockMode - lock mode
properties - standard and vendor-specific properties and hints
the found entity instance or null if the entity does not exist
IllegalArgumentException - if the first argument does not denote an entity type or the second argument is not a valid type for that entity's primary key or is null
TransactionRequiredException - if there is no transaction and a lock mode other than NONE is specified
OptimisticLockException - if the optimistic version check fails
PessimisticLockException - if pessimistic locking fails and the transaction is rolled back
LockTimeoutException - if pessimistic locking fails and only the statement is rolled back
PersistenceException - if an unsupported lock call is made
JPA 2.0