1z0-898: Java EE 6 Java Persistence API Developer Certified Expert

Entity lifecycle callback methods may be defined in which three classes? (Choose three)

Embedded classes
Entity classes
Abstract classes
Entity listener classes
Mapped superclasses
Concrete non-entity superclasses

Correct answer: BDE

Explanation:

Entity Listeners and Callback Methods A method may be designated as a lifecycle callback method to receive notification of entity lifecycle events. A lifecycle callback method can be defined on an entity class, a mapped superclass, or an entity listener class associated with an entity or mapped superclass. Reference: How to inject a spring's service bean into a JPA Entity?http://stackoverflow.com/questions/3747268/how-to-inject-a-springs-service-bean-into-a-jpa-entity

Entity Listeners and Callback Methods

A method may be designated as a lifecycle callback method to receive notification of entity lifecycle events. A lifecycle callback method can be defined on an entity class, a mapped superclass, or an entity listener class associated with an entity or mapped superclass.

Reference: How to inject a spring's service bean into a JPA Entity?

http://stackoverflow.com/questions/3747268/how-to-inject-a-springs-service-bean-into-a-jpa-entity

A developer wrote an entity class with the following method:

Private static Logger logger = Logger.getLogger (“myLogger”);

@PrePersist

@PreUpdate

Public void doA () {

Logger.info (“A”);

}

@PostPersist

@PostUpdate

Public void doB () {

logger.info (“B”);

}

What will the log message contain when an application does the following?

Begins a transaction
Creates the entity
Persists the entity
Commits the transaction
Begins the entity data
Modifies the entity data
Merges the entity
Commits the second transaction

A
A
B
B
A
B
A
B
A
B
B
A
B
The application will throw an exception because multiple lifecycle callback annotations applied to a single method.

Correct answer: B

Given the following code:

Public void create () {

try {

doA () {

} catch (PersistenceException e)

try (doB) ();

} catch (PersistenceException e)

}

Calling method doA will cause an NonUniqueResultException to be thrown. Calling method doB will cause an EntityExistsException to be thrown.

What two options describe what will happen when the create method is called within an application ' uses container managed transactions? (Choose two)

Method doB will never be called.
The current transaction will continue after doA executes.
The current transaction will continue after doB executes.
The current transaction will be marked for rollback when doA is called.
The current transaction will be marked for rollback when doB is called.

Correct answer: BE

Explanation:

B: PersistenceException is thrown by the persistence provider when a problem occurs. All instances of PersistenceException except for instances of NoResultException, NonUniqueResultException, LockTimeoutException, and QueryTimeoutException will cause the current transaction, if one is active, to be marked for rollback. E: EntityExistsException is thrown by the persistence provider when EntityManager.persist(Object) is called and the entity already exists. The current transaction, if one is active, will be marked for rollback.Reference: javax.persistence, Class PersistenceExceptionReference: javax.persistence, Class EntityExistsException

B:

PersistenceException is thrown by the persistence provider when a problem occurs. All instances of PersistenceException except for instances of NoResultException, NonUniqueResultException, LockTimeoutException, and QueryTimeoutException will cause the current transaction, if one is active, to be marked for rollback.

E: EntityExistsException is thrown by the persistence provider when EntityManager.persist(Object) is called and the entity already exists. The current transaction, if one is active, will be marked for rollback.

Reference: javax.persistence, Class PersistenceException

Reference: javax.persistence, Class EntityExistsException

An application that uses pessimistic locking calls an updateData method that results in a LockTimeoutException being thrown. What three statements are correct? (Choose three)

The current transaction continues.
The current statement continues.
The current transaction is rolled back.
The current statement is rolled back.
The LockTimeoutException can NOT be caught.
The LockTimeoutException can be caught, and the updateData method retried.

Correct answer: ADF

Explanation:

LockTimeoutException is thrown by the persistence provider when an pessimistic locking conflict occurs that does not result in transaction rollback. This exception may be thrown as part of an API call, at, flush or at commit time. The current transaction, if one is active, will be not be marked for rollback. Reference: javax.persistence, Class LockTimeoutException

LockTimeoutException is thrown by the persistence provider when an pessimistic locking conflict occurs that does not result in transaction rollback. This exception may be thrown as part of an API call, at, flush or at commit time. The current transaction, if one is active, will be not be marked for rollback.

Reference: javax.persistence, Class LockTimeoutException

A developer has created a deep entity class hierarchy with many polymorphic relationships between entitles. Which inheritance strategy, as defined by the inheritanceType enumerated type, will be most performed in this scenario?

Single table-per-class-hierarchy (InheritanceType.SINGLE_TABLE)
Joined-subclass (inheritanceType. JOINED)
Table-per-concrete-class (inheritanceType.TABLE_PER_CLASS)
Polymorphic join table (inheritanceType. POLYMORPHIC_JOIN_TABLE)

Correct answer: A

Explanation:

The Single Table per Class Hierarchy Strategy This strategy provides good support for polymorphic relationships between entities and queries that cover the entire entity class hierarchy. Note: Enum InheritanceType: * SINGLE_TABLE A single table per class hierarchy. * JOINED A strategy in which fields that are specific to a subclass are mapped to a separate table than the fields that are common to the parent class, and a join is performed to instantiate the subclass. * TABLE_PER_CLASS A table per concrete entity class. Incorrect:Not D: There is no such thing as inheritanceType.POLYMORPHIC_JOIN_TABLE.Reference: Entity Inheritance Mapping Strategiesjavax.persistence, Enum InheritanceType

The Single Table per Class Hierarchy Strategy

This strategy provides good support for polymorphic relationships between entities and queries that cover the entire entity class hierarchy.

Note: Enum InheritanceType:

* SINGLE_TABLE

A single table per class hierarchy.

* JOINED

A strategy in which fields that are specific to a subclass are mapped to a separate table than the fields that are common to the parent class, and a join is performed to instantiate the subclass.

* TABLE_PER_CLASS

A table per concrete entity class.

Incorrect:

Not D: There is no such thing as inheritanceType.POLYMORPHIC_JOIN_TABLE.

Reference: Entity Inheritance Mapping Strategies

javax.persistence, Enum InheritanceType

Vendor:	Oracle
Exam Code:	1z0-898
Exam Name:	Java EE 6 Java Persistence API Developer Certified Expert
Date:	Jan 04, 2018
File Size:	2 MB

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