File Name: hibernate interview questions and answers .zip
Here in this post coding compiler presenting a list of 75 advanced hibernate interview questions for freshers, 1-year experience, 2 years experience, 3 years experience, 4 years experience, 5 years experience. Learn Now.! It provides a framework for mapping an object-oriented domain model to a relational database.
- Hibernate Interview Questions And Answers For Experienced
- 46 hibernate interview questions and answers - freshers, experienced
- Hibernate Interview Questions and Answers
- Hibernate Interview Questions
Hibernate Interview Questions And Answers For Experienced
Hibernate is one of the most widely used ORM tool for Java applications. So I decided to write a post about hibernate interview questions to brush up your knowledge before the interview. Whether you are fresher or experienced, having good knowledge or Hibernate ORM tool helps in cracking interview. Here I am providing important hibernate interview questions with answers to help you brush up your knowledge and impress your interviewer.
Just like other interview questions posts, chances are that I will be adding more questions to this list in future, so you might want to bookmark it for future reference. Recently I have written a lot of posts on hibernate, most of them contains complete downloadable projects. I will provide reference to them as and when needed and you can go through them to refresh your knowledge. Object-relational mapping or ORM is the programming technique to map application domain model objects to the relational database tables.
Hibernate is java based ORM tool that provides framework for mapping application domain objects to the relational database tables and vice versa. Hibernate framework provide option to map plain old java objects to traditional database tables with the use of JPA annotations as well as XML based configuration. Similarly hibernate configurations are flexible and can be done from XML configuration file as well as programmatically.
For a quick overview of hibernate framework usage, you can go through Hibernate Beginners Tutorial. Current JPA version 2. JPA 2. JPA specifications is defined with annotations in javax. Using JPA annotation helps us in writing implementation independent code.
Overall hibernate is the best choice in current market for ORM tool, it contains all the features that you will ever need in an ORM tool.
Hibernate configuration file contains database specific configurations and used to initialize SessionFactory. We provide database credentials or JNDI resource information in the hibernate configuration xml file. Some other important parts of hibernate configuration file is Dialect information, so that hibernate knows the database type and mapping file or class details. Hibernate mapping file is used to define the entity bean fields and database table column mappings. Hibernate supports JPA annotations and it has some other annotations in org.
Some of the important JPA and hibernate annotations used are:. SessionFactory is the factory class used to get the Session objects. SessionFactory is responsible to read the hibernate configuration parameters and connect to the database and provide Session objects. Usually an application has a single SessionFactory instance and threads servicing client requests obtain Session instances from this factory. The internal state of a SessionFactory is immutable.
Once it is created this internal state is set. SessionFactory also provide methods to get the Class metadata and Statistics instance to get the stats of query executions, second level cache details etc. Multiple threads can access it simultaneously to get Session instances. Hibernate Session is the interface between java application layer and hibernate.
This is the core interface used to perform database operations. Lifecycle of a session is bound by the beginning and end of a transaction. Session provide methods to perform create, read, update and delete operations for a persistent object. Hibernate SessionFactory getCurrentSession method returns the session bound to the context. But for this to work, we need to configure it in hibernate configuration file. Once the session factory is closed, this session object gets closed.
Hibernate SessionFactory openSession method always opens a new session. We should close this session object once we are done with all the database operations. We should open a new session for each request in multi-threaded environment.
There is another method openStatelessSession that returns stateless session, for more details with examples please read Hibernate openSession vs getCurrentSession. Hibernate session comes with different methods to load data from database.
For clarification regarding the differences, please read Hibernate get vs load. As the name suggests, hibernate caches query data to make our application faster. Hibernate Cache can be very useful in gaining fast application performance if used correctly.
The idea behind cache is to reduce the number of database queries, hence reducing the throughput time of the application. Hibernate first level cache is associated with the Session object. Hibernate first level cache is enabled by default and there is no way to disable it. However hibernate provides methods through which we can delete selected objects from the cache or clear the cache completely. Any object cached in a session will not be visible to other sessions and when the session is closed, all the cached objects will also be lost.
For better explanation, please read Hibernate First Level Cache. EHCache is the best choice for utilizing hibernate second level cache. Following steps are required to enable EHCache in hibernate application. Hibernate merge can be used to update existing values, however this method create a copy from the passed entity object and return it.
The returned object is part of persistent context and tracked for any changes, passed object is not tracked. For example program, read Hibernate merge. Hibernate save can be used to save entity to database. Problem with save is that it can be invoked without a transaction and if we have mapping entities, then only the primary object gets saved causing data inconsistencies. Also save returns the generated id immediately. Hibernate persist is similar to save with transaction.
Hibernate saveOrUpdate results into insert or update queries based on the provided data. If the data is present in the database, update query is executed. We can use saveOrUpdate without transaction also, but again you will face the issues with mapped objects not getting saved if session is not flushed. For example usage of these methods, read Hibernate save vs persist. Hibernate uses Reflection API to create instance of Entity beans, usually when you call get or load methods. The method Class.
Also the entity beans should implement Comparable or Comparator interface for it to work, read more at java object list sorting. Below code snippet shows you how to get it.
This is done by extending the entity bean, if the entity bean will be final then lazy loading will not be possible, hence low performance. Hibernate query language is case-insensitive except for java class and variable names. Employee is not same as com. The HQL queries are cached but we should avoid it as much as possible, otherwise we will have to take care of associations.
Read more at HQL Example. Hibernate implements a cache region for queries resultset that integrates closely with the hibernate second-level cache. This is an optional feature and requires additional steps in code. This is only useful for queries that are run frequently with the same parameters. First of all we need to configure below property in hibernate configuration file. For normal scenarios, it is however not the recommended approach because we loose benefits related to hibernate association and hibernate first level caching.
Hibernate provides Named Query that we can define at a central location and use them anywhere in the code. Hibernate Named Query helps us in grouping queries at a central location rather than letting them scattered all over the code. Hibernate Named Query syntax is checked when the hibernate session factory is created, thus making the application fail fast in case of any error in the named queries. Hibernate Named Query is global, means once defined it can be used throughout the application.
Hibernate provides Criteria API that is more object oriented for querying the database and getting results. Learn some quick examples at Hibernate Criteria Example.
However we should use it only in Development or Testing environment and turn it off in production environment. Hibernate uses proxy object to support lazy loading. As soon as you reference a child or lookup object via getter methods, if the linked entity is not in the session cache, then the proxy code will go to the database and load the linked object.
It uses javassist to effectively and dynamically generate sub-classed implementations of your entity objects. We can easily implement one-to-one, one-to-many and many-to-many relationships in hibernate. For better understanding, you should go through following tutorials. Transaction management is very easy in hibernate because most of the operations are not permitted outside of a transaction.
So after getting the session from SessionFactory, we can call session beginTransaction to start the transaction. This method returns the Transaction reference that we can use later on to either commit or rollback the transaction.
Any exception thrown by session methods automatically rollback the transaction. When we have relationship between entities, then we need to define how the different operations will affect the other entity. This is done by cascading and there are different types of it. CascadeType , so we need to use the Hibernate CascadeType and Cascade annotations for mappings, as shown in above example. Commonly used cascading types as defined in CascadeType enum are:.
Hibernate 4 uses JBoss logging rather than slf4j used in earlier versions.
46 hibernate interview questions and answers - freshers, experienced
Hibernate is one of the most widely used ORM tool for Java applications. So I decided to write a post about hibernate interview questions to brush up your knowledge before the interview. Whether you are fresher or experienced, having good knowledge or Hibernate ORM tool helps in cracking interview. Here I am providing important hibernate interview questions with answers to help you brush up your knowledge and impress your interviewer. Just like other interview questions posts, chances are that I will be adding more questions to this list in future, so you might want to bookmark it for future reference. Recently I have written a lot of posts on hibernate, most of them contains complete downloadable projects. I will provide reference to them as and when needed and you can go through them to refresh your knowledge.
Hibernate interview questions are asked to the students because it is a widely used ORM tool. The important list of top 20 hibernate interview questions and answers for freshers and professionals are given below. Hibernate is an open-source and lightweight ORM tool that is used to store, manipulate, and retrieve data from the database. It is a programming strategy to map object with the data stored in the database. It simplifies data creation, data manipulation, and data access.
What are the benefits of ORM tool? ORM is helpful in automatically generating keys, managing transaction, hiding SQL queries details, and developing applications in quick manner. Provide the list of collection types in Hibernate? What are the two cache types in Hibernate? First level cache and Secondary level cache are the types of cache in Hibernate.
Questions PDF. Below are the list of Best Hibernate Interview Questions and Answers session object. Download Free: Hibernate Interview Questions PDF.
Hibernate Interview Questions and Answers
Hibernate is a popular framework of Java which allows an efficient Object Relational mapping using configuration files in XML format. After java objects mapping to database tables, database is used and handled using Java objects without writing complex database queries. What is ORM?
If you're looking for Hibernate Interview Questions for Experienced or Freshers, you are at the right place. There are a lot of opportunities from many reputed companies in the world. So, You still have the opportunity to move ahead in your career as Hibernate Developer. It is widely implemented in a variety of enterprise applications, especially in database operations. Hibernate enables users to create persistent classes based on principles like polymorphism, inheritance, composition, association, and collections.
Hibernate Interview Questions
Hibernate is an ORM object-relational mapping tool for Java programming language. It is developed by Red Hat and was started by Gavin King with his colleagues in The original aim was to offer better persistence capabilities than those offered by EJB2 Enterprise Java Beans version 2 , they wanted to simplify the complexities and supplement certain missing features. The information which has been provided will brush up your mind and will substantially contribute to impressing the interviewer so that you fly with high colors. It considers the java objects in a similar way as that of the SQL. It is an Object-Oriented Query Language and is independent of the database.
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