Java developers worldwide struggle to find the best frameworks to use in their programming ventures. Different frameworks offer different features, so it is often difficult to find just one that would suit all of your wants and needs. However, as of late, the Hibernate framework has been more and more noticeable within various programming communities. With the increase in popularity, it is seen as one of the essential tools that a Java programmer should acquire while seeking for a stable and well-paying job. In this tutorial, you’ll learn the essential Hibernate interview questions that will help you score that job as a Java developer.
Table of Contents
- 1. Elementary Hibernate Questions
- 1.1. Question 1: Describe Hibernate.
- 1.2. Question 2: What JPA?
- 1.3. Question 3: What is the criteria API?
- 1.4. Question 4: What is ‘ORM’?
- 1.5. Question 5: Name a few Hibernate benefits.
- 1.6. Question 6: What is the syntax to create a SQL query?
- 1.7. Question 7: Define ‘dialect’.
- 1.8. Question 8: Where are the mapping documents located within the framework?
- 1.9. Question 9: How is it possible to enhance the functionality of built-in interfaces by add new custom interfaces?
- 1.10. Question 10: Name three of the main components of Hibernate.
- 1.11. Question 11: What is the Hibernate configuration file?
- 1.12. Question 12: What is a ‘Hibernate Session’?
- 1.13. Question 13: How can you configure Hibernate?
- 1.14. Question 14: What’s the syntax of adding a criterion into the SQL query?
- 1.15. Question 15: What are the two types of collection in Hibernate?
- 2. Advanced Information
- 2.1. Question 1: Name some of the advantages that Hibernate has over JDBC.
- 2.2. Question 2: What is ‘SessionFactory’?
- 2.3. Question 3: What is the purpose of ‘caching’ in Hibernate?
- 2.4. Question 4: Should you use POJOs in Hibernate?
- 2.5. Question 5: Explain ‘persistent classes’ in Hibernate.
- 2.6. Question 6: Should your use default Hibernate templates?
- 2.7. Question 7: Can you implement ‘Join’ into Hibernate by using SQL?
- 2.8. Question 8: Name and define the three states of objects in Hibernate.
- 2.9. Question 9: Name the default cache in Hibernate.
- 2.10. Question 10: What is the main benefit of the Eclipse plugin?
- 3. Conclusions
Elementary Hibernate Questions
The first part of this tutorial is dedicated to some of the more simple questions. These are examples of questions that you might get at the beginning of your job interview, or if Hibernate isn’t the main framework that your employers are looking for. Even so, it is key to know these questions and answers, for they might become the deciding factor between you doing great in your interview, and flunking it completely.
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Question 1: Describe Hibernate.
A great example of a first question that you’re likely to get during your job interview, your potential employers are going to test your skills in describing the framework. You are likely to encounter similar Hibernate interview questions through ought the job interview - ones that require you to explain a concept or define something.
Hibernate is a Java-based framework. It is designed to create database-based apps. A great feature of the framework (and one of the main ones that it is loved for) is that it represents the database in the form of objects. These objects can then be written without any specific SQL knowledge. This is great because it saves developers and programmers a lot of time - something that has huge value when it comes to programming! Hibernate also has inbuilt object mapping - this minimizes the number of lines of code needed for the apps to function.
Question 2: What JPA?
JPI for shortened means Java Persistence API. It provides a specification for managing the relational data in the application. Java specifications are defined with annotations in javax.persistence package. Using JPA helps in writing implementation independent code. It is important to know as many abbreviations as possible in the Hibernate interview questions, it will help a lot.
Question 3: What is the criteria API?
Criteria is a powerful API that is simple to use and which is used to retrieve entities through criteria object composition.
Question 4: What is ‘ORM’?
ORM is an acronym for “object-related Mapping”. It is a philosophy that is aimed at making data manipulation and access as simple as possible. The way that it achieves this is by (quote on quote) mapping objects according to their data. It’s the very basic concept that Hibernate is built upon, and is derived from Java (it is an object-oriented programming language).
Question 5: Name a few Hibernate benefits.
The Hibernate framework provides a lot of benefits for developers and programmers alike, so you truly do have a wide variety to choose from. However, here are just a few of the more notable ones: support for JPA and XML annotations, fully object-oriented, easily integrated with other various Java frameworks, automatic key generation.
Question 6: What is the syntax to create a SQL query?
To create a SQL query in Hibernate, you would have to use this line of syntax:
Don’t be surprised if you get this and similar Hibernate interview questions during your job interview. The syntax is an important aspect of Hibernate, so you are bound to get asked to provide multiple different answers and examples concerning and involving it.
Question 7: Define ‘dialect’.
A dialect can be a singular file or a group of files (the latter is more often the case). These files are used to connect the Hibernate database with the Java class. You could say that the dialect is like the “translation tool” between Hibernate and its core database.
Question 8: Where are the mapping documents located within the framework?
All of the mapping documents of Hibernate are located within what is known as the Configuration Interface. This interface is used to both stores the before mentioned documents and issue-specific configuration commands to the framework itself.
You could go as far as to say that this could be viewed as one of the tricks Hibernate interview questions. Most employers would ask you something in the lines of “What is the Configuration Interface used for in Hibernate?”. However, the question above is concerned with the actual functions of the interface - you have to know the Configuration Interface to be able to answer swiftly and correct. So, be on the lookout of similar questions!
Question 9: How is it possible to enhance the functionality of built-in interfaces by add new custom interfaces?
The user can use extension interfaces to add any required functionality that is not supported by built-in ones.
Question 10: Name three of the main components of Hibernate.
There are more than three components to choose from, so you really shouldn’t have a problem answering this question. As an example in Hibernate interview questions, you could say session, the above-mentioned configuration, and query.
Question 11: What is the Hibernate configuration file?
The configuration file contains a database of specific configurations and is used to initialize SessionFactory. In the configuration XML file, the user provides database credentials or JNDI (Java Naming and Directory Interface) resource information. The other important part of the Hibernate configuration file is Dialect information, that allows Hibernate to know the database type, mapping file or class details.
Question 12: What is a ‘Hibernate Session’?
The Session is the main tool that operates the database within the Hibernate framework. It is the main tool used to create, issue and execute SQL and HQL-based queries.
This is one of the Hibernate interview questions that you could elaborate upon, stating that the Session in Hibernate isn’t at all thread-safe. This means that every single thread that is related to Session should create and use its own ‘Session instance’, securing it afterward the job is finished.
Question 13: How can you configure Hibernate?
The immediate answer would be that there are two main ways to do so - using XML and then the annotation provided by Java.
In Hibernate versions earlier than Hibernate 4.0, the only way to configure the framework was by utilizing XML. The option to do so with Java-based annotations only became available in versions 4.0 and later. That why you should listen carefully to the Hibernate interview questions that your potential employers give you - did they specify the version of the framework? Which versions are they talking about? Naturally, your best bet is to simply answer by stating both of the possible configuration methods and then elaborating further on - your employers might be quite impressed!
Question 14: What’s the syntax of adding a criterion into the SQL query?
The syntax would look like this:
Question 15: What are the two types of collection in Hibernate?
The two collections of Hibernate are Sorted and Order.
Now that we’ve covered the basics and you can kind of know what to expect out of the beginning of the interview, lets transition and move on to the questions and answers for experienced developers. These are the types of questions that your potential employers might ask to further cement their belief in your knowledge on the topic.
Don’t worry, though - these Hibernate interview questions are advanced in that they might require a more in-depth answer or a more thorough explanation of the topic.
Question 1: Name some of the advantages that Hibernate has over JDBC.
JDBC stands for Java Database Connection. Hibernate has quite a few advantages over JDBC, with some of the more notable ones being: no need to download new drivers once you change the database, comprehension of both SQL and HQL (JDBC can only utilize SQL), preloaded drivers, etc.
Question 2: What is ‘SessionFactory’?
Be careful not mix it up with Session! SessionFactory is the thing that provides instances of Session. All of the data and information that isn’t default on Hibernate is kept in SessionFactory.
Question 3: What is the purpose of ‘caching’ in Hibernate?
In Hibernate, caching allows you to run your application much faster. Caching reduces the number of queries required to successfully run the application, thus increasing performance rate and speed.
Question 4: Should you use POJOs in Hibernate?
This could be classified as one of the double Hibernate interview questions since you’ll first need to know what a POJO even is to answer the question correctly.
POJO stands for a Plain Old Java Object. These are objects that do not require a specific classpath, thus not being restricted in any way, shape or form. It is advisable to use POJOs in your Hibernate projects - this because they will provide a better-working, more fluid code when compared to a standard Java class.
Question 5: Explain ‘persistent classes’ in Hibernate.
Persistent classes are Java classes that store their data (objects) within the tables of the Hibernate framework’s database. They are special in that they need a set constructor for them to function as normal. Proxies - some of the core Hibernate functions - are heavily dependant on the workflow of persistent classes.
A good piece of advice in Hibernate interview questions is that a lot of developers stress concerning the job interviews is that you should always elaborate on the questions, especially the more advanced ones. In doing so, you not only show that you know the answer, but also that you are quite knowledgeable on the topic, in general. This is especially true for questions such as this one - try to give a specific answer, but then expand it with 2-3 more additional sentences. If you do so, you will surely leave a good, lasting impression on your employers.
Question 6: Should your use default Hibernate templates?
Although this can be seen as one of the more subjective Hibernate interview questions, your employers are most likely trying to find out if you know the general pros of using Hibernate templates.
One of the moan advantages of using Hibernate templates is that a lot of functions are fully automated (Session closing, dealing with certain exceptions) - you would have to issue and perform them manually otherwise. Additionally, these templates greatly simplify the process of using Hibernate.
Question 7: Can you implement ‘Join’ into Hibernate by using SQL?
Yes - you can use both SQL and HQL queries to implement Join into Hibernate.
Question 8: Name and define the three states of objects in Hibernate.
One of the more expansive Hibernate interview questions, in total there are three object states - detached, persistent and transient.
Objects become detached once the session is closed by the developer. Detached objects can then turn into persistent ones, with proper methods enabled. Persistent objects are those who are open - they happen whenever you save or retrieve certain instances from the Hibernate database. Transient objects are the “odd ones” - they are objects that have just been created, and are yet to be distinguished by a specific Session.
Question 9: Name the default cache in Hibernate.
The default cache of the Hibernate framework is the EHCache.
Question 10: What is the main benefit of the Eclipse plugin?
The plugin helps developers to write and manage their files in a much easier manner when compared to default Hibernate methods.
We have now covered both the basics and the Hibernate interview questions and answers for experienced developers and programmers. At this point in the tutorial, you should have a pretty good idea of what to expect during your Hibernate job interview. Remember - practice makes perfect! Try not to stress too much and simply study - that will increase your chances of scoring that job by a landslide!
With the knowledge of how to use Hibernate, you can both increase your chances of landing a high-salary job and aid yourself in future individual projects. It is of no secret, though, that the vast majority of people learning Hibernate do so because they want to land that awesome job. And why wouldn’t they! A stable, above-average salary, great working conditions, future career opportunities - who wouldn’t want that?