Mastering the Spring Framework is essential for developing scalable, efficient applications in Java. As one of the most popular frameworks, Spring simplifies Java development, while its modular approach allows you to build powerful, flexible systems.

Why Learn the Spring Framework?

• Industry-Standard Tool: The Spring Framework is a trusted choice for building enterprise-level applications. Many top companies rely on it to create reliable, highly scalable systems that can meet evolving demands.
• Powerful Features: Spring offers numerous features, including dependency injection, aspect-oriented programming, and simplified transaction management. These capabilities streamline the development process and make it easier to build, deploy, and maintain applications.
• Boost Your Career Prospects: As more companies prioritize efficiency and scalability, expertise in the Spring Framework has become increasingly valuable. It empowers developers to improve application performance, maintainability, and flexibility, making you a strong candidate in the job market.
• Great Flexibility: The Spring Framework supports a wide range of components, from MVC to RESTful services, allowing developers to create anything from simple APIs to complex, large-scale applications. Mastering Spring equips you to develop robust, scalable solutions that can easily adapt to changing business needs.

35 Easy Spring Framework Interview Questions and Answers

To help you ace your Spring Framework interviews, here are some frequently asked questions that cover core concepts and common scenarios.

1. What is Spring Framework?

   1. Spring is an integrated framework to develop enterprise applications and to reduce the complexity of enterprise application development.
      Spring framework is a lightweight process and it is loosely coupled
      It supports various frameworks such as Struts, Hibernate, Tapestry, EJB, JSF etc

2. What are the features of Spring framework?

   1. • Inversion of control (IOC)

      • Container

      • Lightweight

      • MVC Framework

      • Aspect oriented Programming (AOP)

      • Transaction Management

      • JDBC Exception Handling

3. What are the modules available in Spring framework?

   1. We have lot of modules available in spring framework like Data access, web, core container, AOP, Test etc.

4. Explain IOC?

   1. IOC stands for in spring is Inversion of Control is used to create configures, objects and assembles their dependencies, manages their entire life cycle. IOC gets the information of objects from a configuration file(XML) or Java Annotations and Java POJO class.

5. Explain DI in Spring framework?

   1. Dependency Injection makes our programming code loosely coupled in otherwords it removes the dependency from the program for easy to manage and test application.

6. What is Spring Configuration file?

   1. XML file is a spring configuration file and it mainly contains the information of classes and describes how these classes are configured and introduced to each other.

7. What is the use of IOC container in Spring framework?

   1. IOC gets the information of objects from a configuration file(XML) and the below tasks are performed in Spring framework
      i.    to instantiate the application class
      ii.    to configure the object
      iii.    to assemble the dependencies between the objects

8. How many ways can Dependency Injection be done?

   1. There are three ways Dependency Injection can be done as follows
      i.    Constructor Injection
      ii.    Setter Injection
      iii.    Interface Injection

9. What is the difference between BeanFactory and ApplicationContext?

   1. BeanFactory and ApplicationContext both are java interfaces but Bean Factory is Basic container and where as ApplicationContext is advance Container.
      ApplicationContext extends BeanFactory and both configurations are using XML Files but ApplicationContext also supports Java configuration.
      BeanFactory provides basic IoC and Dependency Injection (DI) features but ApplicationContext provides more facilities than BeanFactory such as integration with spring AOP.

10. What are the different components of a Spring application?

    1. We have various components of spring application as follows
       i.    Interface
       ii.    Bean class
       iii.    Spring AOP
       iv.    Bean configuration

11. Differentiate between constructor injection and setter injection?

    1. Partial dependency: can be injected using setter injection but it is not possible by constructor. Suppose there are 3 properties in a class, having 3 argument constructor and setters methods. In such case, if you want to pass information for only one property, it is possible by setter method only.
       Overriding: Setter injection overrides the constructor injection. If we use both constructor and setter injection, IOC container will use the setter injection.
       Changes: We can easily change the value by setter injection. It doesn't create a new bean instance always like constructor. So setter injection is flexible than constructor injection

12. What is autowiring in Spring?

    1. The Spring framework enables automatic dependency injection. In other words, by declaring all the bean dependencies in a Spring configuration file, Spring container can autowire relationships between collaborating beans.

13. Explain the AOP module?

    1. The AOP module is used for developing aspects for our Spring-enabled application. Much of the support has been provided by the AOP Alliance in order to ensure the interoperability between Spring and other AOP frameworks.

14. Explain the web module in Spring framework?

    1. The Spring web module is built on the application context module, providing a context that is appropriate for web-based applications. This module also contains support for several web-oriented tasks such as transparently handling multipart requests for file uploads and programmatic binding of request parameters to your business objects. It also contains integration support with Jakarta Struts.

15. What are the different types of IoC (dependency injection)?

    1. Constructor-based dependency injection: Constructor-based DI is accomplished when the container invokes a class constructor with a number of arguments, each representing a dependency on another class.
       Setter-based dependency injection: Setter-based DI is accomplished by the container calling setter methods on your beans after invoking a no-argument constructor or no-argument static factory method to instantiate your bean.

16. What is Spring MVC module?

    1. MVC framework is provided by Spring for building web applications. Spring can easily be integrated with other MVC frameworks, but Spring’s MVC framework is a better choice since it uses IoC to provide for a clean separation of controller logic from business objects. With Spring MVC you can declaratively bind request parameters to your business objects.

17. What are Spring beans?

    1. Beans are created with the configuration metadata that the users supply to the container.
       Beans are managed by the Spring IoC container.
       The Spring Beans are Java Objects that form the backbone of a Spring application.

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

    1. The web.xml file in Spring MVC is used for configuring the DispatcherServlet, defining context parameters, filters, and listeners, as well as handling error pages. While newer Spring applications rely more on annotation-based configuration, web.xml remains essential for certain settings and legacy support.

19. What is the importance of session scope?

    1. It allows creating and maintaining a separated instance of a bean for each user session, ensuring that data associated with a specific user is preserved throughout their interactions with the application.

20. What is bean wiring?

    1. When beans are combined together within the Spring container, it’s called wiring or bean wiring and Spring container needs to know what beans are needed and how the container should use dependency injection to tie them together.

21. What are the advantages of spring AOP?

    1. Spring AOP breaks the code logic into distinct parts because it enables to add or remove concern dynamically before or after business logic for easy to maintain and pluggable.

22. What is JoinPoint?

    1. JoinPoint is any point in your program such as field access, method execution, exception handling etc.
       The joinpoint represents a point in an application where we can plug in an AOP aspect. It is the actual place in the application where an action will be taken using the Spring AOP framework.

23. What are Spring Interceptors?

    1. Spring Interceptors are components in the Spring MVC framework that allow to intercept and process HTTP requests and responses. It provide a way to perform pre-processing and post-processing tasks before and after the actual request is handled by a controller or after the response is generated.

24. Can you inject null and empty string values in Spring?

    1. Yes, you inject null and empty string values in Spring.

25. What is @Autowired annotation?

    1. The @Autowired annotation provides more fine-grained control over where and how auto wiring should be accomplished and in Spring is used to automatically wire (inject) dependencies into a Spring bean.It enables automatic dependency injection, meaning that Spring will automatically find and inject the required dependencies into the bean without the need for manual configuration.

26. What is @Required annotation?

    1. This annotation simply indicates that the affected bean property must be populated at configuration time, through an explicit property value in a bean definition, or through auto wiring. The container throws BeanInitializationException if the affected bean property has not been populated.

27. What is @Qualifier annotation?

    1. When there are more than one bean of the same type and only one is needed to be wired with a property, the @Qualifier annotation is used along with @Autowired annotation to remove the confusion by specifying which exact bean will be wired.

28. What is @RequestMapping annotation?

    1. @RequestMapping annotation is used for mapping a particular HTTP request method to a specific class/ method in controller that will be handling the respective request and This annotation applied on class and method levels.

29. What is DispatcherServlet?

    1. The Spring Web MVC framework is designed around a DispatcherServlet that handles all the HTTP requests and responses.The controller then returns an object of Model And View. The DispatcherServlet checks the entry of view resolver in the configuration file and calls the specified view component.

30. What are the different types of AutoProxying?

    1. AutoProxying types are
       i.    BeanNameAutoProxyCreator
       ii.    DefaultAdvisorAutoProxyCreator
       iii.    Metadata auto proxying

31. What is proxy?

    1. An object which is created after applying advice to a target object is known as a Proxy. In case of client objects the target object and the proxy object are the same.

32. What are the difference between Spring AOP and AspectJ AOP?

    1. Spring AOP is Runtime weaving through proxy is done and in AspectJ AOP is Compile time weaving through AspectJ Java tools is done 
       Spring AOP supports only method level PointCut where as AspectJ AOP suports field level Pointcuts
       Spring AOP is DTD based but AspectJ AOP is schema based and Annotation configuration.

33. How to create instance of BeanFactory interface?

    1. XmlBeanFactory is the implementation class for the BeanFactory interface and The constructor of XmlBeanFactory class receives the Resource object so we need to pass the resource object to create the object of BeanFactory
       For creation of instance beanFactory is
       Resource resource=new ClassPathResource("applicationContext.xml"); 
       BeanFactory factory=new XmlBeanFactory(resource);  

34. How to instanciateApplicationContext interface?

    1. ClassPathXmlApplicationContext class is the implementation class of ApplicationContextinterface.The constructor of ClassPathXmlApplicationContext class receives string, so we can pass the name of the xml file to create the instance of ApplicationContext.
       The following is instantiation of ApplicationContext interface
       ApplicationContext context =     new ClassPathXmlApplicationContext("applicationContext.xml");

35. What is Constructor Injection?

    1. By using <constructor-arg> is the subelement of <bean> to create constructor injection.
       There are three types of injections to create constructor injection
       primitive and String-based values
       Dependent object (contained object)
       Collection values etc.

Scope @ NareshIT:

NareshIT’s Spring Framework Online Training program provides a comprehensive, hands-on approach to mastering Spring, one of the most widely used frameworks in Java development. This course equips you with essential skills to build robust, high-performing applications suitable for enterprise environments.

• Hands-On Projects: Work on real-world projects to design and implement Spring-based applications. These projects simulate actual industry scenarios, giving you practical experience that builds your confidence and skills.

• Learn from Experts: Learn directly from industry professionals who bring their expertise to the course. The curriculum is updated regularly to reflect the latest developments and best practices in Spring, ensuring you're always learning relevant, in-demand skills.

• Comprehensive Learning: Covering all essential components, from dependency injection to Spring MVC and RESTful services, this program provides a well-rounded understanding of Spring. You’ll learn to build, deploy, and manage robust applications ready for production.

• Certification: Upon completing the course, you’ll receive an industry-recognized certificate from NareshIT, showcasing your proficiency in the Spring Framework and increasing your value in the job market.