Frequently Asked Spring Interview Questions

Spring is one of the popular Java frameworks for web applications. During interviews for software development positions, you may be asked to answer questions related to this technology.

In this article, we have listed the Spring interview questions that you can review before a technical interview.

🕵️ While preparing for Spring interviews, Java interview questions can also be beneficial for you.

 

Most Frequently Asked Spring Interview Questions and Answers

1. What is the Spring framework?

Spring is a framework'kind that helps in the development of various types of applications using Java platforms. It is simple and easy to use. It helps resolve real-time technical issues. Spring includes multiple modules such as WEB MVC, IOC, DAO, AOP, Context, and ORM.

 

2. How many modules are there in the Spring Framework and what are they?

Spring consists of different modules, and each module focuses on a specific area of development. Spring is composed of features organized into approximately 20 modules.

The Spring framework consists of many modules such as core, beans, context, expression language, AOP, Aspects, Instrumentation, JDBC, ORM, OXM, JMS, Transaction, Web, Servlet, Struts, etc.

These modules are grouped into Core Container, Data Access/Integration, Web, AOP (Aspect Oriented Programming), Instrumentation, and Test, as shown in the diagram below. 👇

3. What is a Spring configuration file?

The Spring configuration file, is an XML file with an .xml extension that contains information about classes and interfaces. This file describes how classes are configured and how they are introduced to each other.

The Spring configuration file helps manage the application's components using the Spring Framework's Inversion of Control (IoC) principle and the dependency injection mechanism.

 

4. Can a project have more than one Spring configuration file?

In large projects, it is recommended to have multiple Spring configurations to increase maintainability and modularity.

👇 Multiple Java-based configuration files can be loaded:

 

👇 An XML file that includes all configurations can be loaded:

 

5. What are the different components of Spring?

Spring applications generally contain components of different types that serve various purposes. A Spring application typically consists of the following components:

 

• ✔️ Interface: Defines the functions.
• ✔️ Bean class: The Bean class, which is a core component of Spring, contains its properties and functions.
• ✔️ Spring Aspect Oriented Programming (AOP): Provides functionality for cross-cutting concerns.
• ✔️ Bean Configuration File:Contains information about classes and how they are configured.
• ✔️ User Program: Uses the functions.

 

6. How is the Spring framework installed?

1️⃣ To download Spring, go to the official Spring website.

2️⃣ On the website, you will find different versions of Spring. Do not click on the latest framework version. Here you will find three files:

• spring-framework-5.1.4.RELEASE-dist.zip
• spring-framework-5.1.4.RELEASE-docs.zip
• spring-framework-5.1.4.RELEASE-schema.zip

 

3️⃣ Add the file “spring-framework-5.1.4.RELEASE-dist.zip” to your C drive. Now you can run your application on the Spring framework.

 

7. What is Spring Security?

Spring Security is a module of the Spring framework that focuses on authentication and authorization processes in Java applications. CSRF attacks and other common security vulnerabilities are addressed.

 

👉 @EnableWebSecurity annotation allows you to use Spring Security in web applications.

 

8. What is the Spring IOC Container?

The Spring IoC Container is the core of the Spring Framework. This container creates objects, connects them, configures their dependencies, and manages their entire lifecycle. 

The Spring container uses Dependency Injection' to manage the components of an application. It obtains information about objects from a configuration file (XML), Java code, or a Java POJO class. These objects are called beans. 

 

9. What is Dependency Injection in Spring?

Dependency Injection (DI) is a design pattern that eliminates dependencies in programming code to make application management and testing easier.

Dependency Injection allows programming code to be loosely coupled and easier to test.

 

10. What are the types of Dependency Injection in Spring MVC?

1️⃣ Constructor Injection: In constructor injection, dependencies are injected through a class constructor. It is a recommended method by Spring as it ensures all required dependencies are present when the object is created.

2️⃣ Setter Injection: In setter injection, dependencies are injected using setter methods. 

 

3️⃣ Field Injection: In field injection, dependencies are injected directly into class fields. This method is least preferred as it complicates the implementation of required dependencies and testability. 

 

11. What is the purpose of the IoC container? What are its benefits?

The main tasks performed by the IoC container are:

✅ Starting the application class,

✅ Configuring the object,

✅ Aggregating dependencies between objects.

 

Some of the benefits of IoC include:

✅ Minimizes the amount of code in the application.

✅ Facilitates the testing of the application.

✅ Supports loose coupling with minimal effort. Reduces tight coupling between objects, making the system more flexible and resilient to changes.

 

12. How many types of IoC containers are there?

There are two types of IoC containers: 

1️⃣ BeanFactory: It provides the functionalities to create, configure, and manage objects (beans) defined and managed in Spring. BeanFactory allows you to create beans either lazily or pre-instantiated, manage their lifecycle, and perform dependency injection, especially in large and complex applications.

XmlBeanFactory is the implementation class of the BeanFactory interface. The XmlBeanFactory class is used to utilize BeanFactory.👇

 

2️⃣ ApplicationContext: The ApplicationContext interface is built on top of the BeanFactory interface. It provides additional functionalities on top of BeanFactory.

ClassPathXmlApplicationContext class is the implementation class of the ApplicationContext interface. To use ApplicationContext, you need to initialize the ClassPathXmlApplicationContext class as shown below. 👇

 

13. What is the Spring @Controller?

@Controller is an annotation used in the Spring Framework to designate a class as a controller component. It is part of the Spring MVC (Model-View-Controller) architecture used to build web applications in a structured manner. 

@Controller allows a class to function as a controller in Spring MVC. Controllers receive requests from clients, process them, and return a view as a result.

When you annotate a class with @Controller, Spring recognizes it as a controller. It allows handling HTTP requests and creating HTTP responses. Controllers are responsible for processing user requests, interacting with the application's business logic (services), and returning the appropriate view to create the response. The Spring Controller annotation is typically used in conjunction with @RequestMapping-annotated handler methods based on.

 

📍 Example of a @Controller class:

 

14. What is the Spring @RestController?

👉 The @RestController annotation is used to create RESTful web services. @RestController classes work similarly to @Controller classes. However, unlike @Controller, each method call is optimized to return data in JSON or XML formats by default. 

 

15. What is Spring @ResponseStatus?

@ResponseStatus is used to associate an HTTP response status with a controller method or exception class. @ResponseStatus allows you to mark a method or exception class with the status code and message that should be returned.

 

16. What is ContextLoaderListener and what does it do?

✔️ ContextLoaderListener is a Spring Framework component used in Java web applications to load the Spring application context when the web application is started. 

✔️ It helps in starting the IoC container, managing beans, and allowing components to access Spring beans for processing.

 

17. What is Spring @RequestParam?

@RequestParam annotation allows Spring to extract input data that can be transmitted as query parameters, form data, or any optional custom data of a request.

It is used to read form data and bind it to a parameter in the automatically provided method. It maps the request parameter, including form data, query parameters in multipart requests, and parts.

 

18. What is the Spring @PathVariable?

@PathVariable is a Spring annotation that indicates that a method parameter should be bound to a URI template variable. 

@PathVariable is an annotation in the Spring Framework. Using @PathVariable, you can handle different elements within a single controller method using dynamic URL structures.

 

📍 In this example, the expression {id} represents a path variable.

 

19. What is Spring @Autowired?

The Spring @Autowired annotation is used to automatically wire dependencies into a Spring bean. It enables automatic dependency injection, meaning it automatically finds and injects the required dependencies without the need for manual configuration.

 

20. What is Spring @ModelAttribute?

The @ModelAttribute annotation in Spring MVC allows a method to use an object that is sent during the method call. It is used to bind method parameters to model attributes.

Model-View-Controller (MVC) architecture helps in transferring data between the controller and the view. It facilitates data transfer between the controller and the view. 

 

21. What is the importance of the @Repository annotation?

The @Repository annotation in Spring is a marker annotation used for classes that fulfill the role of a data repository or DAO (Data Access Object). It is used to indicate that the class is responsible for data access operations such as reading and writing from a database or any external data source.

 

22. What is BindingResult?

BindingResult is used in Spring MVC to bind and validate data. The advantages provided by BindingResult are:

✅ Catches errors that occur during form submission. 

✅ Helps in preventing exceptions.

 

23. What is a Spring Interceptor?

Spring Interceptors are components in the Spring MVC framework that allow intercepting and processing HTTP requests and responses. They are used to intercept and process client requests. 

Sometimes, you may want to stop an HTTP request and perform some operations on it before passing it to controller handler methods. In such cases, Spring MVC Interceptors are used. 

 

24. What are the differences between the <context:annotation-config> and <context:component-scan> tags?

👉 <context:annotation-config>: is used to enable various annotations in beans managed by Spring. For example, if you have manually defined beans in your XML file and these beans have annotations like @Autowired, @PostConstruct, @PreDestroy, @Resource, etc., <context:annotation-config> is used to enable these annotations.

 👉 <context:component-scan>: Unlike <context:annotation-config>, this tag scans the classpath for classes annotated with @Component, @Service, @Repository, and @Controller, and automatically registers them as beans. In other words, it automatically detects and initializes beans.

 

25. What is Spring MultipartResolver?

➡️ MultipartResolver is an interface defined in Spring MVC used for handling file uploads. When a form is submitted in a Spring web application with the enctype=”multipart/form-data” attribute, MultipartResolver facilitates the uploading of files in the request.

 

26. What is the Spring @Required?

The @Required annotation is used to indicate that a particular property of a bean class must be set. If a property annotated with @Required is not set or is left null, Spring will throw an exception during the initialization phase.

 

27. What is the Spring @Qualifier?

@Qualifier is used when multiple beans of the same type are created and only one of them needs to be injected into a property. It allows you to specify exactly which bean should be injected. The @Qualifier annotation can be used in conjunction with @Autowired.

 

Start Your Spring Career

Spring is a popular framework used by a large community. Having knowledge of Spring can enhance your job prospects and career opportunities.

If you're just starting out, you can join Spring Bootcamps and develop your skills. If you are already an experienced developer with years of expertise, you can sign up with Coderspace, and we can help you find the right job.