Top 40 Hibernate Interview Questions and Answers 2024

Many-to-many relationship in Hibernate without common columns

• Create a third table with foreign keys to both tables

• Use @ManyToMany annotation in both entity classes

• Specify the join table name and column names in @JoinTable annotation

JDBC is a low-level API for connecting to databases, while Hibernate is a high-level ORM framework.

• JDBC requires manual coding for CRUD operations, while Hibernate provides automatic mapping of objects to database tables.

• JDBC is more suitable for small-scale applications, while Hibernate is better for large-scale applications.

• Hibernate provides caching and lazy loading, which improves performance, while JDBC does not have these features.

• Hibernate supports inheritance mapping,...read more

Save() method inserts a new record into the database, while persist() method can also be used to update an existing record.

• save() method is used to insert a new record into the database

• persist() method can also be used to insert a new record, but it can also be used to update an existing record

• save() method returns the generated ID immediately, while persist() method does not

• save() method can be called outside of a transaction, while persist() method must be called within a t...read more

Hibernate is configured in a Spring project using the HibernateTemplate or EntityManagerFactory.

• Hibernate can be configured in a Spring project by defining the necessary beans in the application context XML file.

• The HibernateTemplate class can be used to perform CRUD operations on the database using Hibernate.

• Alternatively, the EntityManagerFactory can be configured to work with Hibernate in a Spring project.

• The Hibernate properties such as database connection details, dialec...read more

Hibernate is an ORM tool used to map Java objects to database tables.

• Hibernate simplifies database access by abstracting the JDBC API

• It provides a framework for mapping an object-oriented domain model to a relational database

• Hibernate supports lazy loading, caching, and transaction management

• It reduces the amount of boilerplate code needed for database operations

• Hibernate is widely used in enterprise Java applications

Difference between save and persist in Hibernate

• Save method returns the generated ID immediately while persist method returns void

• Save method can be called outside of a transaction while persist method must be called within a transaction

• Save method can be used with detached objects while persist method cannot

• Save method can be used with transient objects while persist method cannot

get() method returns null if object is not found in database, while load() method throws ObjectNotFoundException.

• get() method is eager loading while load() method is lazy loading.

• get() method returns a fully initialized object while load() method returns a proxy object.

• get() method is slower than load() method as it hits the database immediately.

• load() method is faster than get() method as it returns a proxy object and hits the database only when required.

Hibernate connects to the database using JDBC (Java Database Connectivity) API.

• Hibernate uses JDBC API to establish a connection to the database.

• It uses JDBC drivers to communicate with the database.

• Hibernate configuration file contains database connection details.

• SessionFactory in Hibernate is responsible for creating sessions and managing connections.

Hibernate is an ORM tool while Spring MVC is a web framework for building Java applications.

• Hibernate simplifies database access by mapping Java classes to database tables.

• Spring MVC provides a model-view-controller architecture for building web applications.

• Hibernate can be used with Spring MVC to handle database operations.

• Spring MVC provides features like request mapping, view resolution, and form handling.

• Both Hibernate and Spring MVC are widely used in Java development.

Hibernate is an ORM tool and JPA is a specification for ORM.

• Hibernate is an open-source ORM tool that maps Java classes to database tables.

• JPA is a specification for ORM that defines a set of interfaces and rules for ORM tools to follow.

• Hibernate implements the JPA specification and provides additional features.

• Hibernate and JPA simplify database access by abstracting away SQL queries and providing a more object-oriented approach.

• Example: Hibernate can be used to map a Java c...read more

Database can be created through Hibernate by defining entity classes, mapping them to database tables, configuring Hibernate properties, and using Hibernate API to interact with the database.

• Define entity classes representing tables in the database

• Map entity classes to database tables using annotations or XML configuration

• Configure Hibernate properties in a configuration file like hibernate.cfg.xml

• Use Hibernate API to perform CRUD operations on the database

n+1 issue in Hibernate refers to the problem of excessive database queries being executed due to lazy loading.

• Occurs when a query fetches an entity and its associated entities one at a time instead of all at once

• Can be solved by using eager loading or batch fetching

• Can also be solved by using a join fetch query

• Can lead to performance issues and slow down the application

VPN stands for Virtual Private Network, a secure connection that allows users to access the internet privately and securely.

• VPN creates a secure and encrypted connection over a less secure network, such as the internet.

• It allows users to access resources on a remote network as if they were directly connected to that network.

• VPN can be used to protect sensitive data, bypass geo-restrictions, and enhance privacy and security online.

Types of mapping in hibernate include one-to-one, one-to-many, many-to-one, and many-to-many mappings.

• One-to-one mapping: Each instance of one entity is associated with exactly one instance of another entity.

• One-to-many mapping: Each instance of one entity is associated with multiple instances of another entity.

• Many-to-one mapping: Multiple instances of one entity are associated with exactly one instance of another entity.

• Many-to-many mapping: Multiple instances of one entity...read more

Rollback in Hibernate is used to undo the changes made to the database during a transaction.

• Rollback is used to revert any changes made to the database within a transaction if an error occurs.

• It is typically called in catch block of try-catch-finally block to handle exceptions.

• Example: session.beginTransaction(); try { // database operations } catch (Exception e) { session.getTransaction().rollback(); }

Hibernate supports two types of caches: Level 1 (session) cache and Level 2 (SessionFactory) cache.

• Level 1 cache is associated with the session object and is enabled by default.

• Level 2 cache is shared across sessions and requires configuration.

• Level 2 cache can be implemented using various providers like Ehcache, Infinispan, Hazelcast, etc.

Spring JPA is a part of the Spring Data project that makes it easier to work with JPA. Hibernate is a popular ORM framework.

• Spring JPA is a higher level abstraction on top of JPA, providing more features and simplifying development.

• Hibernate is a powerful ORM framework that provides mapping between Java objects and database tables.

• Spring JPA can be used with Hibernate as the underlying ORM provider.

• Hibernate offers more flexibility and control over the database interactions c...read more

Different types of object relations in Hibernate include one-to-one, one-to-many, many-to-one, and many-to-many.

• One-to-one: Each record in one table is related to only one record in another table.

• One-to-many: Each record in one table can be related to multiple records in another table.

• Many-to-one: Multiple records in one table can be related to only one record in another table.

• Many-to-many: Multiple records in one table can be related to multiple records in another table.

Hibernate manages object lifecycle through three states: transient, persistent, and detached.

• When an object is created, it is in the transient state.

• When the object is saved using session.save() method, it becomes persistent.

• When the session is closed or the object is explicitly detached using session.evict() method, it becomes detached.

• Detached objects can be re-attached to a new session using session.update() or session.merge() methods.

• Objects can also be deleted using sess...read more

Hibernate is an ORM tool that maps Java classes to database tables.

• Hibernate simplifies database access by abstracting the underlying SQL queries.

• It provides a way to map Java classes to database tables using annotations or XML files.

• Hibernate supports various types of associations between classes, such as one-to-one, one-to-many, and many-to-many.

• It also supports caching to improve performance.

• Hibernate can be integrated with Spring framework for easier configuration and man...read more

The n+1 problem in Hibernate occurs when a query results in multiple individual queries being executed for each row fetched.

• Occurs when a query fetches a collection and then for each element in the collection, another query is executed to fetch related data

• Can be resolved by using fetch joins or batch fetching to reduce the number of queries

• Improves performance by reducing the number of database round trips

getSession() retrieves the current session while load() method loads the object by its identifier.

• getSession() method is used to retrieve the current session from the session factory.

• load() method is used to load the object by its identifier.

• getSession() method returns null if there is no current session.

• load() method throws an exception if the object is not found in the database.

• getSession() method is used for read and write operations while load() method is used for read-on...read more

JDBC is a Java API for connecting and executing queries on a database. Hibernate is an ORM framework that simplifies database interactions.

• JDBC is a low-level API for database connectivity in Java, requiring manual handling of SQL queries and connections.

• Hibernate is a high-level ORM framework that maps Java objects to database tables, abstracting away the need for manual SQL queries.

• JDBC is more suitable for simple database operations, while Hibernate is preferred for comple...read more

Hibernate in Spring is an ORM tool that simplifies database operations by mapping Java objects to database tables.

• Hibernate is an ORM (Object-Relational Mapping) tool used in Spring framework

• It simplifies database operations by mapping Java objects to database tables

• It provides automatic generation of SQL queries based on Java classes and annotations

Hibernate is an ORM tool that simplifies database interactions in Java applications.

• Hibernate configuration involves setting up database connection details in hibernate.cfg.xml

• Entities are mapped to database tables using annotations or XML mapping files

• SessionFactory is created to obtain Session objects for database operations

• Transactions are managed using Session object to ensure data consistency

• Example: Entity class 'User' mapped to 'users' table, fetching user data using H...read more

Hibernate is an open-source object-relational mapping framework for Java.

• Hibernate simplifies the process of mapping Java objects to database tables.

• It provides a framework for performing database operations using object-oriented programming concepts.

• Hibernate supports automatic generation of SQL queries and provides caching mechanisms for improved performance.

• It offers features like lazy loading, transaction management, and data retrieval using HQL (Hibernate Query Language)...read more

JPA is a specification while Hibernate is an implementation of JPA.

• JPA is a Java specification for managing relational data in applications.

• Hibernate is an ORM framework that implements the JPA specification.

• Hibernate provides additional features beyond JPA, such as caching and lazy loading.

• JPA is vendor-neutral, allowing developers to switch between different JPA implementations.

• Hibernate is a popular choice for JPA implementation due to its extensive features and community ...read more

JPA is a specification while Hibernate is an implementation of JPA. JPA provides a standard API for ORM frameworks.

• JPA is a standard API for ORM frameworks

• JPA provides a vendor-neutral interface

• JPA allows for easy switching between ORM frameworks

• Hibernate is an implementation of JPA

• Hibernate provides additional features beyond JPA

Hibernate many to many mapping allows for a relationship where multiple instances of one entity are related to multiple instances of another entity.

• Use @ManyToMany annotation in Hibernate to establish many to many relationship between entities

• Create a join table to store the relationship between the two entities

• Specify the mapping details such as cascade type, fetch type, and join column details

get() method returns null if the object is not found in the database, while load() method throws an exception.

• get() method is eager loading while load() method is lazy loading.

• get() method hits the database immediately while load() method hits the database only when the object is accessed.

• get() method returns a proxy object while load() method returns a real object.

• get() method is used when we are not sure if the object exists in the database while load() method is used when ...read more

Hibernate is better than JDBC due to its object-relational mapping capabilities, automatic table creation, and improved performance.

• Hibernate provides object-relational mapping (ORM) which simplifies database interactions by mapping Java objects to database tables, eliminating the need for manual SQL queries.

• Hibernate can automatically generate SQL queries based on the Java objects, reducing the amount of code that needs to be written.

• Hibernate can create database tables auto...read more

Spring Hibernate is a framework that combines Spring and Hibernate to simplify the development of Java applications.

• Spring Hibernate integrates the Spring framework with Hibernate ORM for database access.

• It provides a way to manage transactions, data access, and other aspects of application development.

• Developers can use annotations and XML configuration to define the mapping between Java objects and database tables.

• It helps in reducing boilerplate code and improving producti...read more

Second level cache in Hibernate is used to cache data at the session factory level to reduce database hits.

• Second level cache stores objects across sessions to reduce database calls

• Improves performance by reducing database hits

• Configurable cache providers like Ehcache, Infinispan can be used

Hibernate is a popular ORM framework that simplifies database interactions in Java applications by mapping Java objects to database tables.

• Hibernate is an ORM (Object-Relational Mapping) framework that simplifies database operations in Java applications.

• It provides a way to map Java objects to database tables and vice versa.

• Hibernate supports JPA (Java Persistence API) annotations for defining mappings between Java classes and database tables.

• It handles the database operation...read more

get() method retrieves data from the database immediately, while load() method returns a proxy object and loads data only when needed.

• get() method returns null if the object is not found in the database, while load() method throws an ObjectNotFoundException.

• get() method hits the database immediately, while load() method returns a proxy object without hitting the database until actual data is needed.

• get() method is used when we are not sure if the object exists in the database...read more

JDBC is a low-level API for connecting to databases in Java, while Hibernate is a high-level ORM framework that simplifies database interactions.

• JDBC requires writing SQL queries manually, while Hibernate provides an object-oriented approach to database operations.

• Hibernate handles mapping Java objects to database tables, while JDBC requires manual mapping.

• Hibernate provides caching mechanisms for improved performance, while JDBC does not have built-in caching.

• JDBC is more su...read more

Hibernate is an ORM tool that integrates with Spring for database operations.

• Hibernate provides a way to map Java objects to database tables.

• Spring provides a framework for managing dependencies and integrating with other technologies.

• Together, Hibernate and Spring can simplify database operations and improve performance.

• Example: Using Hibernate with Spring, we can easily perform CRUD operations on a MySQL database.

• Example: We can also use Spring's transaction management to e...read more

Hibernate is used for ORM mapping in projects to interact with databases.

• Mapping Java classes to database tables

• Managing database connections

• Performing CRUD operations

• Implementing caching mechanisms

• Supporting transactions

Hibernate is an open-source object-relational mapping (ORM) framework for Java applications.

• Hibernate simplifies the development of database-driven applications by mapping Java objects to database tables.

• It provides a query language called HQL (Hibernate Query Language) for querying databases using object-oriented syntax.

• Hibernate supports automatic generation of primary key values, caching, and transaction management.

• Example: Hibernate can be used to map a Java class represe...read more

Criteria in Hibernate is used to create and execute dynamic queries.

• Criteria is an interface in Hibernate that allows the creation of dynamic queries without using HQL or SQL.

• Criteria queries are type-safe and can be easily modified at runtime.

• Criteria queries can be used to fetch entities based on certain conditions or restrictions.

• Example: Criteria criteria = session.createCriteria(Employee.class);

Hibernate is a popular Java ORM framework that simplifies database interactions by mapping Java objects to database tables.

• Hibernate is an ORM (Object-Relational Mapping) framework that allows developers to map Java objects to database tables and vice versa.

• It provides a way to perform database operations using Java objects without writing complex SQL queries.

• Hibernate handles the mapping of Java classes to database tables, and Java data types to SQL data types.

• It supports va...read more