Top 15 Spring Data JPA Interview Questions with Answers

Hello guys, If you are preparing for a Spring developer interview and looking for some Spring Data JPA Interview questions then you have come to the right place. Earlier, I have shared frequently asked interview questions on Spring Boot, Spring Cloud, Microservices, and Spring MVC in general, and in this article, I will share frequently asked Spring Data JPA Interview Questions with Answers for Java developers. Spring is one of the most popular and widely used frameworks. Spring Data JPA is an important part of the framework as it makes working with JPA or any JPA implementation like Hibernate easier.  

Spring Data JPA 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. 

Questions related to Spring data JPA are always asked in the Spring interview and that's why a Spring developer should always be familiar 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. 

While Hibernate is a full-fledged JPA implementation, Spring Data JPA provides an additional layer of abstraction or a better API to work with JPA. It's not a JPA implementation, which means you still need to use a JPA implementation like Hibernate but Spring data features like finder methods, and JPQL makes working with database much easier. 

As mentioned above, the Spring framework is widely used, so there are many job opportunities for Spring developers. 

Along with other important concepts, it is also necessary to know Spring data JPA to clean Java web developer interviews where Spring is used. If you are new to Spring Data or spring framework, I highly recommend you to join a comprehensive course like Spring Framework 6: Beginner to Guru course on Udemy which covers both Spring Data JPA as well as core Spring concepts. 

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. 

There are many popular JPA implementations available in the Java world like Hibernate. You can further see these Spring Data JPA using Hibernate course to learn more about how to use Hibernate with Spring Data JPA in Java application. 

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:
a) Repository
b) PagingAndSortingRepository
c) CrudRepository
d) JpaRepository
e) QueryByExampleRepository


8. What is PagingAndSortingRepository? (answer)
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

@Query("select e from Employee e where se.name = ?1") 
List<Employee> getEmployees(String name); 

You can further see Spring Framework: Spring Data JPA course on Pluralsight to learn more about @Query annotation of Spring Data JPA. 

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? 

These practice questions are also good for Spring professional certification, one of the most in-demand certifications for Java developers. 

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. 

 Other Java and Spring articles you may like

• 10 Things Java Developer should learn (goals)
• 5 courses to learn Spring Boot and Spring Cloud ( courses)
• 20 Spring Boot Interview Questions for Java Programmers (questions)
• Top 5 Books and Courses to learn RESTful Web Service (books)
• 10 Tips to become a better Java developer (tips)
• 5 Spring Boot Annotations for full-stack Java developers (tutorial)
• 5 Courses to learn Spring Cloud and Microservices (courses)
• 5 Spring Boot Features Every Java Developer Should Know (features)
• 5 Course to Master Spring Boot online (courses)
• 10 Courses to learn Spring Security with OAuth 2 (courses)
• 3 ways to change Tomcat port in Spring Boot (tutorial)
• 10 Spring MVC annotations Java developers should learn (annotations)
• 10 Tools Java Developers use in their day-to-day life (tools)
• Top 5 Courses to learn Microservices in Java? (courses)
• 10 Advanced Spring Boot Courses for Java Programmers (courses)
• 3 Best Practices Java Programmers can learn from Spring (best practices)

Thanks for reading this article so far. If you found these Spring Data JPA Interview questions and answers useful then please share them with your colleagues and friends. If you have any questions or feedback then please drop a note. 

P. S. - If you want to learn about Spring Data and JPA then I highly recommend you to join Spring Data JPA using Hibernate course by Bharat Thippireddy on Udemy. It's one of the best courses to learn Spring Data JPA for Java developers.