Spring Interview Prep: most asked interview Question and answer for Freshers

Spring Interview Prep: A well-liked Java-based framework for creating enterprise apps is called Spring. It offers an extensive collection of tools and APIs that facilitate code reuse and streamline the development process. Because of its modular architecture, which lets developers select just the parts their projects require, Spring is well-known.

A software engineer with skill in building applications with the Spring framework is known as a Spring developer. They know how to use all of Spring’s capabilities and components with ease and have a solid grasp of Java programming. Typically, projects requiring scalable, stable, and effective applications are worked on by spring developers.

Here are some Questions for Spring Interview Prep: most asked interview Question and answer for Freshers

1.What is IOC and DI?

IOC (Inversion of Control) and DI (Dependency Injection) are fundamental concepts in software development, particularly in object-oriented programming and frameworks like Spring.

The term “IOC” describes a concept in which an external container or framework gains authority over object creation and dependency management, reversing the role of the application code. The container handles the creation and management of dependencies, taking over from the application in this regard. More adaptability, modularity, and testability are thus possible in the application.

IOC is implemented via a technique called DI. Rather to the object developing dependencies on its own, it entails injecting them into the object at runtime. Several methods, such as constructor injection, setter injection, or field injection, can be used to do this. DI encourages loose connection between objects, which facilitates testing and makes the code easier to maintain.

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2. What is the role of IOC container in spring?

Throughout Spring, the lifespan and dependencies of objects inside the application are managed by the IOC container. Using dependencies and relationships specified in configuration files or annotations, it serves as a central hub for the creation, configuration, and assembly of objects.

• create the instance
• configure the instance, and
• assemble the dependencies

The IOC container facilitates loose coupling between objects by taking care of these duties, which increases the application’s modularity, testability, and maintainability. Additionally, it streamlines the development process by automating a large number of repetitive operations related to managing dependencies and object generation.

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3.What is AOP?

AOP (Aspect-Oriented Programming) is a programming paradigm that allows for the modularization of cross-cutting concerns, which are concerns that affect multiple parts of an application but are not directly related to the core functionality of the application. Examples of cross-cutting concerns include logging, security, caching, and transaction management.

These issues are frequently dispersed across the code in conventional object-oriented programming, which makes it challenging to manage and maintain. In order to solve this issue, AOP offers a way to group related issues into distinct modules known as aspects. The application code can then use these features at particular join points, like method calls or exception handling. This method increases the application’s overall modularity, maintainability, and capacity for code reuse.

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4. What is JoinPoint?

In Aspect-Oriented Programming (AOP), a JoinPoint designates a particular application execution point where an aspect can be applied. Whether it’s a method call, method execution, exception handling, or field access, it’s a clearly defined place in the program’s control flow.

JoinPoints give you the exact locations from which elements can intercept and change how an application behaves. Aspects can offer further functionality, like logging, security, or caching, without changing the main application code by locating and focusing on particular JoinPoints. Code reusability, maintainability, and modularity are all enhanced by this division of responsibilities.

5. What is Pointcut?

A declarative expression that specifies the collection of JoinPoints where an aspect should be applied is called a shortcut in aspect-oriented programming, or AOP. It serves as a filter, determining which precise points in the application’s control flow should be where the aspect’s advice—that is, the code that needs to be run—is carried out.

Typically, the AOP framework provides a particular language or syntax for defining shortcuts. They can be determined by a number of factors, including the method’s name, the class or package to which it belongs, the parameters that are sent to the method, and the method’s return type. Developers can ensure that an element only impacts the specified JoinPoints by precisely controlling where its functionality is injected into the application by specifying the Pointcut.

6.  What are the Spring Boot Starters?

Pre-packaged dependencies called Spring Boot Starters make it easy to incorporate widely used libraries and frameworks into your Spring Boot applications, therefore streamlining the development process. They make it simpler to get started with different functionality by combining a collection of relevant dependencies and the necessary configurations, eliminating the need to manually configure each dependent separately.

Because of their modular nature, starters are simple to add or remove from your project in accordance with your unique needs. This lowers project complexity and encourages flexibility. Spring Web (for creating web applications), Spring Data JPA (for communicating with databases), Spring Security (for putting security measures in place), and Spring Cloud (for creating distributed systems) are a few of the well-liked Spring Boot Starters. With Starters, developers can concentrate on creating the essential logic of their application, leaving common chores to be handled by the pre-configured dependencies.

7.What is Spring Boot Actuator?

A subproject of Spring Boot called Actuator offers a set of functionality for maintaining and watching over Spring Boot applications that are ready for production use. It provides access to a variety of endpoints that may be used to examine the environment, metrics, health, and other operational information of the application.

Actuator endpoints are usually reachable by HTTP queries, and they can be used to collect data regarding the configuration, resource consumption, and performance of the application. This information can be useful for performance optimization, problem solving, and learning more about how the program behaves in real-world settings. Actuator further facilitates custom endpoints, enabling programmers to reveal more data or features unique to their apps.

8. What is thyme leaf?

Thymeleaf is a template engine built on Java that lets programmers make dynamic HTML templates for websites. Because it makes use of HTML and XML syntax, it is simple to understand and include into Spring Boot projects. The main objective of Thymeleaf is to offer a naturally occurring template language that is machine-processable and developer-friendly.

Thymeleaf’s ability to process templates both statically and dynamically is one of its primary strengths. This implies that templates can be analyzed at runtime to produce dynamic content based on application data, or they can be preprocessed during development to identify issues early. Thymeleaf is an adaptable tool for creating intricate web interfaces since it offers a range of functions for managing conditional logic, looping, and formatting data.

9.What is @RestController annotation in Spring Boot?

A variant of the @Controller annotation created especially for creating RESTful web services is the @RestController annotation used in Spring Boot. When attached to a class, it signifies that the class has methods that manage HTTP requests and provide responses in XML or JSON formats, which are appropriate for RESTful APIs.

The @RestController annotation automatically translates method return values into HTTP replies, in contrast to the @Controller annotation, which necessitates the usage of a view resolver to generate HTML templates. This facilitates the creation of APIs that may be used by a variety of clients, such as web browsers, mobile apps, and other services, and makes the development of RESTful services simpler.

10.What is @RequestMapping annotation in Spring Boot?

In Spring Boot, the @RequestMapping annotation is used to map HTTP requests to particular methods inside a controller class. It lets developers specify which HTTP methods (GET, POST, PUT, DELETE, etc.) are supported as well as the URL patterns that will cause a specific method to be executed.

You can build RESTful APIs using the @RequestMapping annotation that can respond appropriately to various HTTP queries. You could designate, for instance, a GET mapping for data retrieval, a POST mapping for data creation, a PUT mapping for updating current data, and a DELETE mapping for data deletion. An extensible and declarative method of mapping HTTP requests to the functionality of your application is offered by this annotation.

11.List the advantages of Spring Framework.

• The layered architecture of the Spring Framework allows you to utilize what you need and discard what you don’t.
• POJO (Plain Old Java Object) Programming is made possible by the Spring Framework, and this permits testability and continuous integration.
• Dependency Injection and Inversion of Control make JDBC simpler.
• There is no vendor lock-in, and it is open-source.

12. What is a Spring configuration file?

A text-based file called a Spring configuration file lists all of the parts, dependencies, and connections between them in a Spring application. It serves as a design for the architecture of the application, outlining the creation, assembly, and management of objects by the Spring container.

Configuration files can be written in XML or annotations based on Java, among other formats. Elements are used in XML-based configuration to define beans (objects), their attributes, and dependencies. Annotations are used to provide the same information directly on classes and methods in annotation-based setup. The needs of the project and one’s personal preferences determine the configuration format to be used.

13. What do you mean by Dependency Injection? 

Dependency Injection (DI) is a design pattern in which dependencies are added to an object at runtime as opposed to the object generating them on its own. Loose coupling between objects is encouraged by the separation of object creation and dependency management, which improves the code’s modularity, testability, and maintainability.

In DI, an external container or framework—like the Spring IoC container—is given the authority to create and supply dependencies. After examining an object’s dependencies, the container injects the necessary instances into the constructor or setter methods of the object. This facilitates easier management and testing of the program by providing more flexibility and control over the dependencies of the object.

14. Differentiate between BeanFactory and ApplicationContext.

BeanFactory	ApplicationContext
It is an interface found in the BeanFactory class of org.springframework.beans.factory.	The org.springframework.context.ApplicationContext defines this interface.
Lazy initialization is used.	Eager/Aggressive initialization is used.
It uses the syntax to offer a resource object explicitly.	It independently generates and maintains resource objects.
It is not in favour of internationalization.	It encourages globalization.
It doesn’t supports annotation based dependency	Annotation-based dependence is supported.

15. What is the use of @Autowired annotation?

Dependencies are automatically wired into a bean using Spring’s @Autowired annotation. By doing away with the requirement for manual configuration using XML or Java configuration classes, it streamlines the process of injecting dependencies.

When you add the @Autowired annotation to a field, setter method, or constructor parameter, Spring will automatically look for and insert the bean into the designated location. Either a method or a class can be used for this. You may encourage loose coupling and make your Spring apps more maintainable by using the @Autowired annotation.

16.What is the importance of the web.xml in Spring MVC?

Modern Spring Boot applications do not require the web.xml file, although it is still necessary for setting up the servlet container and connecting Spring MVC with the web application. It defines the servlets, filters, and servlet context parameters. It acts as the main configuration file for the web application.

17.What is the importance of session scope?

Web applications’ session scope offers a way to save information unique to a certain user’s session. The data kept in session scope is only available during that session, which usually reflects a sequence of user-web application interactions. This indicates that the information is kept confidential and not accessible to other users.

Session scope is significant because it can save state during several HTTP requests made inside the same session. For features like shopping carts, login authentication, and customized user experiences to be implemented, this is necessary. Applications are able to monitor user preferences, keep track of login status, and customize the experience for every user by keeping session data.

18.What is spring security?

For applications built on Spring, Spring Security is a powerful framework that offers extensive security capabilities. It makes it easier to integrate permission, authentication, and other security measures, freeing up developers to concentrate on creating the essential features of their apps.

19. What is the use of @Transactional annotation in Spring?

Managing database transactions inside of your application may be done declaratively with Spring’s @Transactional annotation. It makes handling transaction-related tasks, such committing or rolling back changes, and setting transaction boundaries easier.

You can indicate that a method’s execution should take place inside of a transaction by annotating a method or class with @Transactional. In order to avoid inconsistent data changes, the transaction can be automatically rolled back in the event that an exception arises while the method is being executed. This promotes uniformity and data integrity throughout your application.

20.What is the distinction between Spring MVC and Spring?

Java web applications are commonly constructed using the Model-View-Controller architecture with the help of the Spring Framework’s Spring MVC (Model-View-Controller) package. To put it briefly, Spring provides an IoC framework with dependency injection, and Spring MVC leverages this feature to offer an application development framework.

It’s critical that your candidate understands the difference between Spring Boot and Spring MVC. While Spring Boot is very opinionated and aims to reduce the overhead of having a developer design a working web application, Spring MVC is configuration-heavy yet offers feature-rich customizations. Even though they spend different amounts of time developing and configuring, they can nonetheless produce the same outcomes.

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