Hibernate is 1 of the most pop persistent frameworks inward Java world. Hibernate offers object to relational (ORM) solution which frees Java developers from writing tedious, hard to read in addition to cluttered JDBC code converting SQL columns into Object properties. Apart from freeing Java developer from writing JDBC in addition to database interaction code, Hibernate likewise offers the out-of-box solution on caching, proxying in addition to lazy loading which drastically improves the surgical operation of your Java Web application. Given it's of import inward Java Web application evolution patch Hibernate has cash inward one's chips of 1 of the most sought after science in addition to goes mitt inward mitt alongside Spring framework. That's why Hibernate interview questions are likewise rattling pop inward Java interviews. Earlier I stimulate got shared about Spring MVC interview questions in addition to due to pop demand, I am forthwith sharing 20 strange Hibernate questions from diverse Java interviews.
These questions are rattling useful for both telephone in addition to the face-to-face circular of interviews in addition to both beginners in addition to experienced Java developers upwards to 2 to five years tin exercise goodness from these questions. If you lot are actively preparing for Java interviews than you lot tin likewise cheque out Java Programming Interview Exposed, it non exclusively contains interview questions from Spring in addition to Hibernate but likewise other of import Java topics e.g. amount Java, information construction in addition to algorithms, Servlet, JSP, JSF in addition to blueprint patterns.
Since no listing is consummate without user involvement, hence if you lot stimulate got seen whatever skillful Hibernate questions on your interviews, which is non on this listing in addition to hence experience complimentary to percentage alongside us. You tin likewise percentage your ain questions for which you lot are looking answers or you lot experience it's a skillful inquiry to live asked on Java JEE programming interviews.
What is Hibernate?
Hibernate is an ORM (Object-relational Mapping) framework, which allows the developer to concentrate on job concern logic past times taking assist of persistence of information past times itself. Java developer tin write code using object in addition to Hibernate tin accept assist of creating those object from information loaded from the database in addition to saving update dorsum to the database.
What are the advantages of Hibernate over JDBC? (detailed answer)
Apart from Persistence i.e. saving in addition to loading information from Database, Hibernate likewise provides next benefits
1) Caching
2) Lazy Loading
3) Relationship administration in addition to provides code for mapping an object to the data
4) The developer is complimentary from writing code to load/store information into the database.
Difference betwixt get() vs load() method inward Hibernate? (detailed answer)
This is 1 of the most oftentimes asked Hibernate interview question, I stimulate got seen it several times. The key departure betwixt get() in addition to load() method is that load() volition throw an exception if an object alongside id passed to them is non found, but get() volition render null. Another of import departure is that charge tin render proxy without hitting the database unless required (when you lot access whatever attribute other than id) but get() e'er cash inward one's chips to the database, hence sometimes using load() tin live faster than the get() method. It makes feel to work the load() method if you lot know the object exists but get() method if you lot are non certain near object's existence.
What is N+1 SELECT job inward Hibernate? (detailed answer)
The N+1 SELECT job is a result of lazy loading in addition to charge on need fetching strategy. In this case, Hibernate ends upwards executing N+1 SQL queries to populate a collection of due north elements. For example, if you lot stimulate got a List of due north Items where each Item has a dependency on a collection of Bid object. Now if you lot desire to discovery the highest bid for each item in addition to hence Hibernate volition burn 1 query to charge all items in addition to due north subsequent queries to charge Bid for each item. So inward club to discovery the highest bid for each item your application halt upwards firing N+1 queries. It's 1 of the of import Hibernate interview questions in addition to I propose to read chapter thirteen of Java Persistence alongside Hibernate to sympathise this job inward to a greater extent than details.
What are about strategies to solve the N+1 SELECT job inward Hibernate? (detailed answer)
This is the follow-up inquiry of previous Hibernate interview question. If you lot reply the lastly query correctly in addition to hence you lot would live most probable asked this one. Here are about strategies to solve the N+1 problem:
1) pre-fetching inward batches, this volition cut down N+1 job to N/K + 1 job where K is size of batch
2) subselect fetching strategy
3) disabling lazy loading
What is the departure betwixt save() in addition to persist() method inward Hibernate? (detailed answer)
Main departure betwixt save() in addition to persist() method is that, salve returns a Serializable object spell render type of persist() method is void, hence it doesn't render anything. Here is a prissy diagram which explains the land transition inward Hibernate:
What is the requirement for a Java object to cash inward one's chips Hibernate entity object? (detailed answer)
It should non live lastly in addition to must supply a default, no-argument constructor. See the detailed reply to acquire to a greater extent than near the special requirement for a Java object to cash inward one's chips Hibernate Entity.
What are dissimilar types of caches available inward Hibernate? (detailed answer)
This is about other mutual Hibernate interview question. Hibernate provides the out-of-box caching solution but at that topographic point are many caches e.g. offset score cache, 2nd score cache in addition to query cache. First score cache is maintained at Session score in addition to cannot live disabled but the 2nd score cache is required to live configured alongside external cache provider similar EhCache.
What is the departure betwixt offset in addition to 2nd score cache inward Hibernate? (detailed answer)
This is over again follow-up of previous Hibernate interview question. The offset score cache is maintained at Session score spell the 2nd score cache is maintained at SessionFactory score in addition to shared past times all sessions. You tin read these books to acquire to a greater extent than near caching inward Hibernate.
Does Hibernate Session interface is thread-safe inward Java? (detailed answer)
No, Session object is non thread-safe inward Hibernate in addition to intended to live used with-in unmarried thread inward the application.
Does SessionFactory is thread-safe inward Hibernate? (detailed answer)
SessionFactory is both Immutable in addition to thread-safe in addition to it has simply 1 unmarried instance inward Hibernate application. It is used to create Session object in addition to it likewise supply caching past times storing SQL queries stored past times multiple session. The 2nd score cache is maintained at SessionFactory level. This tin live a hard in addition to tricky inquiry for less experienced Java developers who are non familiar alongside thread-safety in addition to Immutability.
What is dissimilar betwixt Session in addition to Sessionfactory inward Hibernate? (detailed answer)
This is about other pop Hibernate interview question, by in addition to large at a telephonic circular of interviews. The top dog departure betwixt Session in addition to SessionFactory is that quondam is a single-threaded, short-lived object spell afterward is Immutable in addition to shared past times all Session. It likewise lives until the Hibernate is running. Another departure betwixt Session in addition to SessionFactory is that quondam provides offset score cache spell SessionFactory provides the Second score cache.
What is touchstone query inward hibernate? (detailed answer)
Criteria is a simplified API for retrieving entities past times composing Criterion objects likewise known equally Criterion query. This is a rattling convenient approach for functionality similar "search" screens where you lot tin filter information on multiple weather equally shown inward the next example:
What are other ORM frameworks? Any choice of Hibernate?
This is a full general question, sometimes asked to start the conversation in addition to other times to complete the interview. EJB in addition to TopLink from Oracle are ii of the most pop choice to Hibernate framework.
What is the departure betwixt save() in addition to saveOrUpdate() method of Hibernate? (detailed answer)
Though both save() in addition to saveOrUpdate() method is used to shop object into Database, the key departure betwixt them is that salve tin exclusively INSERT records but saveOrUpdate() tin either INSERT or UPDATE records.
What is departure betwixt getCurrentSession() in addition to openSession() inward Hibernate? (detailed answer)
An interesting Hibernate interview inquiry equally you lot mightiness stimulate got used both getCurrentSession() in addition to openSession() to obtain an instance of Session object. I stimulate got left this inquiry unanswered for you lot to reply or discovery an reply based on your experience.
What is Hibernate Query Language (HQL)? (detailed answer)
Hibernate query language, HQL is an object-oriented extension to SQL. It allows you lot to query, store, update, in addition to hollo upwards objects from a database without using SQL. This inquiry is likewise similar to the before inquiry near Criterion query, Java developers who stimulate got non used Hibernate extensively volition non know much near features similar HQL in addition to Criterion.
When exercise you lot work merge() in addition to update() inward Hibernate? (detailed answer)
This is 1 of the tricky Hibernate interview questions. You should work update() if you lot are certain that the Hibernate session does non incorporate an already persistent instance alongside the same id in addition to work merge() if you lot desire to merge your modifications at whatever fourth dimension without considering the land of the session. See Java Persistence alongside Hibernate for to a greater extent than details.
The departure betwixt sorted in addition to ordered collection inward Hibernate? (detailed answer)
The top dog departure betwixt sorted in addition to ordered collection is that sorted collection form the information inward JVM's heap retentiveness using Java's collection framework sorting methods spell ordered collection is sorted using club past times clause inward the database itself. H5N1 sorted collection is to a greater extent than suited for pocket-sized dataset but for a large dataset, it's amend to work ordered collection to avoid OutOfMemoryError inward Java application.
How exercise you lot log SQL queries issued past times the Hibernate framework inward Java application?
You tin work the show_sql belongings to log SQL queries issued past times the Hibernate framework, Just add together the next delineate inward your Hibernate configuration file:
What are the iii states of a Hibernate Persistence object tin be? (detailed answer)
The Hibernate persistent or entity object tin alive inward next iii states:
1) transient
2) persistent
3) detached
What is the departure betwixt the transient, persistent in addition to detached land inward Hibernate? (detailed answer)
New objects created inward Java plan but non associated alongside whatever hibernate Session are said to live inward the transient state. On the other hand, an object which is associated alongside a Hibernate session is called Persistent object. While an object which was before associated alongside Hibernate session but currently it's non associate is known equally a detached object. You tin telephone vociferation upwards save() or persist() method to shop those object into the database in addition to convey them into the Persistent state. Similarly, you lot tin re-attach a detached object to hibernate sessions past times calling either update() or saveOrUpdate() method.
Which cache is used past times Session Object inward Hibernate? First score or 2nd score cache? (detailed answer)
H5N1 Session object uses the first-level cache. As I told before the 2nd score cache is used at SessionFactory level. This is a skillful inquiry to cheque if Candidate has been working inward hibernate or not. If he has non worked inward Hibernate from a long fourth dimension in addition to hence he would acquire confused inward this question.
That's all inward this listing of Hibernate Interview inquiry for Java and JEE developers. In this article, nosotros stimulate got covered a lot of oftentimes asked Hibernate inquiry for both beginners in addition to experienced Java developers from all of import topics of Hibernate framework e.g. Hibernate fundamentals, caching, collection mapping, surgical operation tuning, mutual issues in addition to Hibernate vs JDBC.
If you lot discovery that you lot lack noesis inward whatever especial area, I propose cash inward one's chips thorough next resources to create total those gaps inward your knowledge.
Further Learning
Introduction To Hibernate
Spring in addition to Hibernate for Beginners
Hibernate Interview Questions Preparation Course
Thanks for reading this article, if you lot similar this article in addition to interview inquiry in addition to hence delight percentage alongside your friends in addition to colleagues. If you lot stimulate got whatever inquiry or feedback in addition to hence delight drib a comment.
These questions are rattling useful for both telephone in addition to the face-to-face circular of interviews in addition to both beginners in addition to experienced Java developers upwards to 2 to five years tin exercise goodness from these questions. If you lot are actively preparing for Java interviews than you lot tin likewise cheque out Java Programming Interview Exposed, it non exclusively contains interview questions from Spring in addition to Hibernate but likewise other of import Java topics e.g. amount Java, information construction in addition to algorithms, Servlet, JSP, JSF in addition to blueprint patterns.
Since no listing is consummate without user involvement, hence if you lot stimulate got seen whatever skillful Hibernate questions on your interviews, which is non on this listing in addition to hence experience complimentary to percentage alongside us. You tin likewise percentage your ain questions for which you lot are looking answers or you lot experience it's a skillful inquiry to live asked on Java JEE programming interviews.
20 Hibernate Questions from Java JEE Interviews
Here is my selected listing of xx Hibernate based questions for Java developers. It contains questions from Hibernate fundamentals, one-to-one, in addition to one-to-many mappings, caching, Hibernate vs JDBC comparison, pros in addition to cons of Hibernate, known problems alongside Hibernate, in addition to Performance improvement.What is Hibernate?
Hibernate is an ORM (Object-relational Mapping) framework, which allows the developer to concentrate on job concern logic past times taking assist of persistence of information past times itself. Java developer tin write code using object in addition to Hibernate tin accept assist of creating those object from information loaded from the database in addition to saving update dorsum to the database.
What are the advantages of Hibernate over JDBC? (detailed answer)
Apart from Persistence i.e. saving in addition to loading information from Database, Hibernate likewise provides next benefits
1) Caching
2) Lazy Loading
3) Relationship administration in addition to provides code for mapping an object to the data
4) The developer is complimentary from writing code to load/store information into the database.
Difference betwixt get() vs load() method inward Hibernate? (detailed answer)
This is 1 of the most oftentimes asked Hibernate interview question, I stimulate got seen it several times. The key departure betwixt get() in addition to load() method is that load() volition throw an exception if an object alongside id passed to them is non found, but get() volition render null. Another of import departure is that charge tin render proxy without hitting the database unless required (when you lot access whatever attribute other than id) but get() e'er cash inward one's chips to the database, hence sometimes using load() tin live faster than the get() method. It makes feel to work the load() method if you lot know the object exists but get() method if you lot are non certain near object's existence.
What is N+1 SELECT job inward Hibernate? (detailed answer)
The N+1 SELECT job is a result of lazy loading in addition to charge on need fetching strategy. In this case, Hibernate ends upwards executing N+1 SQL queries to populate a collection of due north elements. For example, if you lot stimulate got a List of due north Items where each Item has a dependency on a collection of Bid object. Now if you lot desire to discovery the highest bid for each item in addition to hence Hibernate volition burn 1 query to charge all items in addition to due north subsequent queries to charge Bid for each item. So inward club to discovery the highest bid for each item your application halt upwards firing N+1 queries. It's 1 of the of import Hibernate interview questions in addition to I propose to read chapter thirteen of Java Persistence alongside Hibernate to sympathise this job inward to a greater extent than details.
What are about strategies to solve the N+1 SELECT job inward Hibernate? (detailed answer)
This is the follow-up inquiry of previous Hibernate interview question. If you lot reply the lastly query correctly in addition to hence you lot would live most probable asked this one. Here are about strategies to solve the N+1 problem:
1) pre-fetching inward batches, this volition cut down N+1 job to N/K + 1 job where K is size of batch
2) subselect fetching strategy
3) disabling lazy loading
What is the departure betwixt save() in addition to persist() method inward Hibernate? (detailed answer)
Main departure betwixt save() in addition to persist() method is that, salve returns a Serializable object spell render type of persist() method is void, hence it doesn't render anything. Here is a prissy diagram which explains the land transition inward Hibernate:
What is the requirement for a Java object to cash inward one's chips Hibernate entity object? (detailed answer)
It should non live lastly in addition to must supply a default, no-argument constructor. See the detailed reply to acquire to a greater extent than near the special requirement for a Java object to cash inward one's chips Hibernate Entity.
What are dissimilar types of caches available inward Hibernate? (detailed answer)
This is about other mutual Hibernate interview question. Hibernate provides the out-of-box caching solution but at that topographic point are many caches e.g. offset score cache, 2nd score cache in addition to query cache. First score cache is maintained at Session score in addition to cannot live disabled but the 2nd score cache is required to live configured alongside external cache provider similar EhCache.
What is the departure betwixt offset in addition to 2nd score cache inward Hibernate? (detailed answer)
This is over again follow-up of previous Hibernate interview question. The offset score cache is maintained at Session score spell the 2nd score cache is maintained at SessionFactory score in addition to shared past times all sessions. You tin read these books to acquire to a greater extent than near caching inward Hibernate.
Does Hibernate Session interface is thread-safe inward Java? (detailed answer)
No, Session object is non thread-safe inward Hibernate in addition to intended to live used with-in unmarried thread inward the application.
Does SessionFactory is thread-safe inward Hibernate? (detailed answer)
SessionFactory is both Immutable in addition to thread-safe in addition to it has simply 1 unmarried instance inward Hibernate application. It is used to create Session object in addition to it likewise supply caching past times storing SQL queries stored past times multiple session. The 2nd score cache is maintained at SessionFactory level. This tin live a hard in addition to tricky inquiry for less experienced Java developers who are non familiar alongside thread-safety in addition to Immutability.
What is dissimilar betwixt Session in addition to Sessionfactory inward Hibernate? (detailed answer)
This is about other pop Hibernate interview question, by in addition to large at a telephonic circular of interviews. The top dog departure betwixt Session in addition to SessionFactory is that quondam is a single-threaded, short-lived object spell afterward is Immutable in addition to shared past times all Session. It likewise lives until the Hibernate is running. Another departure betwixt Session in addition to SessionFactory is that quondam provides offset score cache spell SessionFactory provides the Second score cache.
What is touchstone query inward hibernate? (detailed answer)
Criteria is a simplified API for retrieving entities past times composing Criterion objects likewise known equally Criterion query. This is a rattling convenient approach for functionality similar "search" screens where you lot tin filter information on multiple weather equally shown inward the next example:
List books = session.createCriteria(Book.class) .add(Restrictions.like("name", "java%") ) .add(Restrictions.like("published_year", "2015")) .addOrder(Order.asc("name") ) .list();This tin live a tough inquiry if you lot are non using Hibernate on a daily basis, I stimulate got interviewed several Java developers who stimulate got used Hibernate but doesn't know near Criterion query or API.
What are other ORM frameworks? Any choice of Hibernate?
This is a full general question, sometimes asked to start the conversation in addition to other times to complete the interview. EJB in addition to TopLink from Oracle are ii of the most pop choice to Hibernate framework.
What is the departure betwixt save() in addition to saveOrUpdate() method of Hibernate? (detailed answer)
Though both save() in addition to saveOrUpdate() method is used to shop object into Database, the key departure betwixt them is that salve tin exclusively INSERT records but saveOrUpdate() tin either INSERT or UPDATE records.
What is departure betwixt getCurrentSession() in addition to openSession() inward Hibernate? (detailed answer)
An interesting Hibernate interview inquiry equally you lot mightiness stimulate got used both getCurrentSession() in addition to openSession() to obtain an instance of Session object. I stimulate got left this inquiry unanswered for you lot to reply or discovery an reply based on your experience.
What is Hibernate Query Language (HQL)? (detailed answer)
Hibernate query language, HQL is an object-oriented extension to SQL. It allows you lot to query, store, update, in addition to hollo upwards objects from a database without using SQL. This inquiry is likewise similar to the before inquiry near Criterion query, Java developers who stimulate got non used Hibernate extensively volition non know much near features similar HQL in addition to Criterion.
When exercise you lot work merge() in addition to update() inward Hibernate? (detailed answer)
This is 1 of the tricky Hibernate interview questions. You should work update() if you lot are certain that the Hibernate session does non incorporate an already persistent instance alongside the same id in addition to work merge() if you lot desire to merge your modifications at whatever fourth dimension without considering the land of the session. See Java Persistence alongside Hibernate for to a greater extent than details.
The departure betwixt sorted in addition to ordered collection inward Hibernate? (detailed answer)
The top dog departure betwixt sorted in addition to ordered collection is that sorted collection form the information inward JVM's heap retentiveness using Java's collection framework sorting methods spell ordered collection is sorted using club past times clause inward the database itself. H5N1 sorted collection is to a greater extent than suited for pocket-sized dataset but for a large dataset, it's amend to work ordered collection to avoid OutOfMemoryError inward Java application.
How exercise you lot log SQL queries issued past times the Hibernate framework inward Java application?
You tin work the show_sql belongings to log SQL queries issued past times the Hibernate framework, Just add together the next delineate inward your Hibernate configuration file:
<property name=”show_sql”> true </property>
What are the iii states of a Hibernate Persistence object tin be? (detailed answer)
The Hibernate persistent or entity object tin alive inward next iii states:
1) transient
2) persistent
3) detached
What is the departure betwixt the transient, persistent in addition to detached land inward Hibernate? (detailed answer)
New objects created inward Java plan but non associated alongside whatever hibernate Session are said to live inward the transient state. On the other hand, an object which is associated alongside a Hibernate session is called Persistent object. While an object which was before associated alongside Hibernate session but currently it's non associate is known equally a detached object. You tin telephone vociferation upwards save() or persist() method to shop those object into the database in addition to convey them into the Persistent state. Similarly, you lot tin re-attach a detached object to hibernate sessions past times calling either update() or saveOrUpdate() method.
Which cache is used past times Session Object inward Hibernate? First score or 2nd score cache? (detailed answer)
H5N1 Session object uses the first-level cache. As I told before the 2nd score cache is used at SessionFactory level. This is a skillful inquiry to cheque if Candidate has been working inward hibernate or not. If he has non worked inward Hibernate from a long fourth dimension in addition to hence he would acquire confused inward this question.
That's all inward this listing of Hibernate Interview inquiry for Java and JEE developers. In this article, nosotros stimulate got covered a lot of oftentimes asked Hibernate inquiry for both beginners in addition to experienced Java developers from all of import topics of Hibernate framework e.g. Hibernate fundamentals, caching, collection mapping, surgical operation tuning, mutual issues in addition to Hibernate vs JDBC.
If you lot discovery that you lot lack noesis inward whatever especial area, I propose cash inward one's chips thorough next resources to create total those gaps inward your knowledge.
Further Learning
Introduction To Hibernate
Spring in addition to Hibernate for Beginners
Hibernate Interview Questions Preparation Course
Thanks for reading this article, if you lot similar this article in addition to interview inquiry in addition to hence delight percentage alongside your friends in addition to colleagues. If you lot stimulate got whatever inquiry or feedback in addition to hence delight drib a comment.
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