Spring Data not only reduces your data access code but also provides you with tons of query flexibility. It also boosts and enhances your data models and gives you enterprise-level features. In short, it’s essential for the Java stack.
with Spring Data JPA. One of the common doubts among Java developers is about Spring Data and Hibernate and many of them don’t understand the difference between these two essential frameworks.
As mentioned above, the Spring framework is widely used, so there are many job opportunities for Spring developers.
20 Spring Data JPA Interview Questions with Answers
In this article, we will list the top 15 questions related to Spring JPA and then there are a few more Spring Data questions for you to practice and research on your own. You can use these questions to revise key Spring Data concepts as well as prepare for both telephonic and face-to-face round of Spring developer interviews.
1. What is JPA?
Answer: JPA stands for Java Persistence API. It is a Java specification used to persist data between the relational database and Java objects. It acts as a bridge between object-oriented domain models and relational databases. Since interaction with database from Java application is very common, JPA was created to standardize this interaction.
2. What are some advantages of using JPA?
Answer: Here are some advantages of Java Persistence API or JPA:
- JPA reduces the burden of interacting with databases.
- Annotation in JPA reduces the cost of creating a definition file.
- It is user-friendly.
- JPA providers help merge applications.
3. What is the Spring data repository? (answer)
Answer: Spring data repository is a very important feature of JPA. It helps in reducing a lot of boilerplate code. Moreover, it decreases the chance of errors significantly. This is also the key abstraction that is provided using the Repository interface. It takes the domain class to manage as well as the id type of the domain class as Type Arguments.
4. What is the naming convention for finder methods in the Spring data repository interface?
Answer: This is another key feature of Spring Data JPA API which makes writing query method really easy. The finder method should use a special keyword, i.e. “find”, followed by the name of the variable. For example, findByLastName().
5. Why is an interface not a class?
Answer: Interface is not a class because it does not contain concrete methods. It can contain only abstract methods.
6. Can we perform actual tasks like access, persist, and manage data with JPA?
Answer: No, we can’t because JPA is only a Java specification.
7. How can we create a custom repository in Spring data JPA?
Answer: To create a custom repository, we have to extend it to any of the following interfaces:
8. What is PagingAndSortingRepository?
Answer: The PagingAndSortingRepository provides methods that are used to retrieve entities using pagination and sorting. It extends the CrudRepository interface.
9. What is @Query used for? (example)
Answer: Spring Data API provides many ways to define SQL query which can be executed and Query annotations one of them. The @Query is an annotation that is used to execute both JPQL and native SQL queries.
10. Give an example of using @Query annotation with JPQL.
Answer: Here is an example of @Query annotation from Spring Data Application which returns all active orders from the database:
@Query("SELECT order FROM Orders o WHERE o.Disabled= 0") Collection<User> findAllActiveOrders();
and, here is another example, which returns matching employees from the database
"select e from Employee e where se.name = ?1") List<Employee> getEmployees(String name);(
11. Can you name the different types of entity mapping.
Answer: one-to-one mapping, one-to-many mapping, many-to-one mapping, and many-to-many mapping.
12. Define entity and name the different properties of an entity.
Answer: An entity is a group of states bundled (or associated) together in a single unit. It behaves like an object. It also becomes a major constituent of the object-oriented paradigm.
13. What is PlatformTransactionMangaer?
Answer: PlatformTransactionMangaer is an interface that extends TransactionManager. It is the central interface in Spring’s transaction infrastructure.
14. How can we enable Spring Data JPA features?
Answer: To enable Spring data JPA features, first we have to define a configuration class and then, we can use @EnableJpaRepositoties annotation with it. This annotation will enable the features.
15. Differentiate between findById() and getOne().
Answer: The findById() is available in CrudRepository while getOne() is available in JpaRepository. The findById() returns null if record does not exist while the getOne() will throw an exception called EntityNotFoundException.
And, here are some Spring Data JPA Practice questions for you, I haven’t provided the answer to these questions but you can find them by doing some research. You can post the correct answers to these spring Data JPA question in the comments and I will pick the right one to put it here with your name.
16. Are you able to participate in a given transaction in Spring while working with JPA?
17. Which PlatformTransactionManager(s) can you use with JPA?
18. What do you have to configure to use JPA with Spring? How does Spring Boot make this easier?
19. How are Spring Data repositories implemented by Spring at runtime?
That’s all about the frequently asked Spring Data JPA Interview Questions and Answers. So these were the top 15 questions related to Spring Data JPA. Generally, the Spring data JPA interview questions are more or less related to the above questions listed in this article but it’s not guaranteed that you will get these questions in a real interview. Instead of mugging these questions I strongly suggest you use them to learn the essential Spring Data JPA concepts better.
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