Top 22 Spring Interview Questions Answers for Java JEE Developers

Spring framework interview questions are on the rise on Java EE and core Java interviews Spring, which is obvious given Spring is the best framework available for Java application development and now Spring IOC container and Spring MVC framework are used as a de-facto framework for all new Java development. Because of its popularity,  interview questions from spring framework are top on any list of Core Java Interview questions. I thought to put together some spring interview questions and answers which have appeared on many Java and J2EE interviews and useful for practicing before appearing on any Java Job interview. I first wrote this article a long back and even its content is still relevant I thought to update it, especially after finishing my list of Spring Boot Interview Questions recently.

This list of Spring interview questions and answers contains questions from Spring fundamentals e.g. Spring IOC and Dependency Injection, Spring MVC Framework, Spring Security, Spring AOP etc, because of length of this post I haven't included Spring interview questions from Spring JDBC and JMS which is also a popular topic in core Java and J2EE interviews. I suggest preparing those as well.

Anyway, these Spring questions are not very difficult and based on fundamentals like what is default scope of Spring bean? which is mostly asked during the first round or the telephonic round of Java interview. Although you can find answers to these Spring interview questions by doing Google I have also included answers for most of the questions for your quick reference.

As I have said it before both Spring and Spring MVC, and now Spring Boot are fantastic Java frameworks and if you are not using it then it's a good time to start using them, these questions will give you some head start as well. Spring MVC can be used to develop both standalone Java web application as well as RESTful Web Services using Spring.

If you are completely new to Spring framework, I suggest you to first take a look at Spring Framework 5: Beginner to Guru  course, otherwise, most of these question will not make any sense to you. It's also one of the most up-to-date courses which not only covers the basics of IOC and DI container but also advanced concepts like reactive programming with Spring 5.

Top Spring Interview Questions and Answers

These articles cover Interview questions from different Spring Framework projects like Spring MVC, Core Spring, and Spring with REST and Spring MVC particularly. I have also listed resources and linked some articles to learn more and get some more practice questions if you are interested in further learning.

Now let’s start with questions, theseSpring Interview Questions are not very tricky or tough and based upon primary concepts of spring framework.

If you are developing an application using Spring framework then you may be, already familiar with many of these Java and Spring interview questions and answers. Nevertheless, it’s a good recap before appearing in any Spring and Java interview.

Core Spring Interview Questions

Question 1: What is IOC or inversion of control? (answer)

Answer: This Spring interview question is the first step towards the Spring framework and many interviewers start Spring interview from this question. As the name implies Inversion of the control means now we have inverted the control of creating the object from our own using new operator to container or framework.

Now it’s the responsibility of the container to create an object as required. We maintain one XML file where we configure our components, services, all the classes, and their property. We just need to mention which service is needed by which component and container will create the object for us.

This concept is known as dependency injection because all object dependency (resources) is injected into it by the framework.

Example:

				<bean id="createNewStock" class="springexample.stockMarket.CreateNewStockAccont"> <property name="newBid"/>   </bean>

In this example, CreateNewStockAccont class contain getter and setter for newBid and container will instantiate newBid and set the value automatically when it is used. This whole process is also called wiring in Spring and by using annotations it can be done automatically by Spring, referred to as auto-wiring of bean in Spring.

Question 2: Explain the Spring Bean-LifeCycle.

Following steps explain their life cycle inside the container.

1. The container will look the bean definition inside the configuration file (e.g. bean.xml).

2 using reflection container will create the object and if any property is defined inside the bean definition then it will also be set.

3. If the bean implements the BeanNameAware interface, the factory calls setBeanName() passing the bean’s ID.

4. If the bean implements the BeanFactoryAware interface, the factory calls setBeanFactory(), passing an instance of itself.

5. If there are any BeanPostProcessors associated with the bean, their post- ProcessBeforeInitialization() methods will be called before the properties for the Bean are set.

6. If an init() method is specified for the bean, it will be called.

7. If the Bean class implements the DisposableBean interface, then the destroy() method will be called when the Application no longer needs the bean reference.

8. If the Bean definition in the Configuration file contains a 'destroy-method' attribute, then the corresponding method definition in the Bean class will be called.

These were just some of the Spring Fundamentals I can cover here if you are interested to learn more I suggest you take a look at Spring Master Class - Beginner to Expert , an end-to-end course to learn Spring.

Question 3: What is Bean Factory, have you used XMLBeanFactory?

Ans: BeanFactory is factory Pattern which is based on IOC design principles.it is used to make a clear separation between application configuration and dependency from actual code. The XmlBeanFactory is one of the implementations of Bean Factory which we have used in our project.

The org.springframework.beans.factory.xml.XmlBeanFactory is used to create bean instance defined in our XML file.

BeanFactory factory = new XmlBeanFactory(new FileInputStream("beans.xml"));

Or

ClassPathResource resorce = new ClassPathResource("beans.xml"); XmlBeanFactory factory = new XmlBeanFactory(resorce);

Question 4: What are the difference between BeanFactory and ApplicationContext in Spring? (answer)

Answer: This one is a very popular Spring interview question and often asks in an entry-level interview. ApplicationContext is the preferred way of using spring because of the functionality provided by it and the interviewer wanted to check whether you are familiar with it or not.

ApplicationContext.

BeanFactory

Here we can have more than one config files possible

In this only one config file or .xml file

Application contexts can publish events to beans that are registered as listeners

Don't support.

Support internationalization (I18N) messages

It’s not

Support application life-cycle events, and validation.

Doesn’t support.

Supports many enterprise services such as JNDI access, EJB integration, remoting

Doesn’t support.

Question 5: What is AOP?

Answer: The core construct of AOP is the aspect, which encapsulates behaviors affecting multiple classes into reusable modules. AOP is a programming technique that allows a developer to modularize crosscutting concerns, that cuts across the typical divisions of responsibility, such aslogging and transaction management.

Spring AOP, aspects are implemented using regular classes or regular classes annotated with the @Aspect annotation. You can also check out these 30+ Spring MVC interview questions  for more focus on Java web development using the Spring MVC framework.

Question 6: Explain Advice?

Answer: It’s an implementation of aspect; advice is inserted into an application at join points. Different types of advice include “around,” “before” and “after” advice

Question 7: What are the joint Point and point cut?

Ans: This is not really a spring interview questions I would say an AOP one.  Similar toObject-oriented programming, AOP is another popular programming concept which complements OOPS. A join point is an opportunity within the code for which we can apply an aspect. In Spring AOP, a join point always represents a method execution.

Pointcut: a predicate that matches join points. A pointcut is something that defines what join-points advice should be applied.

Here are few more Spring fundamental interview questions for practice

Question 8: Difference between the setter and constructor injection in Spring? (answer)

Setter injection is more flexible than constructor injection because you must remember the type and order of constructor parameter. Also, constructor injection is generally used to inject the mandatory dependency, while setter can be used to inject the optional dependency.

Question 9: Difference between Factory Pattern and Dependency Injection in Java?(answer)

Even though both allow you to reduce coupling in code, dependency injection is much more flexible and easier to test than Factory pattern.

Questions 10. Difference between @Autowired and @ Inject annotation in Spring? (answer)

Question 11: What are the different modules in spring?

Answer: spring has seven core modules

1.      The Core container module

2.      Application context module

3.      AOP module (Aspect Oriented Programming)

4.      JDBC abstraction and DAO module

5.      O/R mapping integration module (Object/Relational)

6.      Web module

7.      MVC framework module

Spring MVC Interview Questions Answers

Questions 12: What is the difference between @Controller and @RestController in Spring MVC? (answer)

Even though both are used to indicate that a Spring bean is a Controller in Spring MVC setup, @RestController is better when you are developing RESTful web services using Spring MVC framework. It's a combination of @Controller + @ResponseBody annotation which allows the controller to directly write the response and bypassing the view resolution process, which is not required for RESTful web service.

It also instructs DispatcherServlet to use different HttpMessageConverters to represent the response in the format client is expecting e.g. HttpMessageJackson2Convert to represent response in JSON format and JAXB based message converts to generate XML response.

You can further see REST with Spring  course by Baeldung to learn more about developing RESTful Web Services using Spring 4 and Spring 5.

Question 13: What is the difference between a singleton and prototype bean?

Ans: This is another popular spring interview questions and an important concept to understand. Basically, a bean has scopes which define their existence on the application.

Singleton: means single bean definition to a single object instance per Spring IOC container.

Prototype: means a single bean definition to any number of object instances.

Whatever beans we defined in spring framework are singleton beans.

There is an attribute in bean tag named ‘singleton’ if specified true then bean becomes singleton and if set to false then the bean becomes a prototype bean.  By default, it is set to true. So, all the beans in spring framework are by default singleton beans.

				<bean id="createNewStock" class="springexample.stockMarket.CreateNewStockAccont" singleton=”false”> <property name="newBid"/> </bean>

Question 14: What is the role of DispatcherServlet in Spring MVC?(answer)

The DispatcherServlet is very important from Spring MVC perspective, it acts as a FrontController i.e. all requests pass through it. It is responsible for routing the request to the controller and view resolution before sending the response to the client.

When Controller returns a Model or View object, it consults all the view resolvers registered to find the correct type of ViewResolver which can render the response for clients.

In case of RESTful Web Services, the DispatcherServlet is also responsible for using HttpMessageConverter to represent the response in the JSON, XML, or TEXT format, depending on the content negotiation between Client and Server like if client sends request with HTTP accept header as "application/json" then DispatcherServlet will ask the HttpMessageJackson2Converter to convert the response into JSON format.

You can further see the free Introduction to Spring MVC  course from Pluralsight to learn more about Spring MVC and DispatcherServlet.

Question 15: How to call the stored procedure from Java using Spring Framework? (answer)

Question 16: How to Setup JDBC Database connection pool in Spring Web application? (answer)

Questions 17: Difference between @ReqeustParam and @PathVariable in Spring MVC? (answer)

Questions 18: Difference between @Component, @Service, @Controller, and @Repositoring annotation in Spring MVC? (answer)

Question 19: What type of transaction Management Spring support?

Ans: This spring interview question is a little difficult as compared to previous questions just becausetransaction management is a complex concept and not every developer familiar with it. Transaction management is critical in any applications that will interact with the database.

The application has to ensure that the data is consistent and the integrity of the data is maintained.  Following two types of transaction management is supported by spring:

1. Programmatic transaction management

2. Declarative transaction management.

If you need more questions, you can also check out the Java Programming Interview exposed  book from Wrox publication, apart from various Java topics it also contains some really good Spring framework, Hibernate, and Spring MVC questions with detailed explanation.

Also, Hibernate is mostly used in Spring, so don't forget to prepare someHibernate interview questions along with Spring.

Spring Security Interview Questions Answer

Some of the readers requested to provide Spring Security interview questions and answer, So I thought to update this article with a few of Spring security question I came across.

Here are those:

20. How do you control the concurrent Active session using Spring Security? (answer)

Another Spring interview question which is based on Out of box feature provided by Spring framework. You can easily control How many active session a user can have with a Java application by using Spring Security.

Apart from that Spring Security also provides the "remember me" feature which you can use to provide easier access for your users by remembering their login details on their personal computer. You can further see Learn Spring Security  course by Eugen Paraschiv to learn more about advanced details of Spring Security.

21. How do you set up LDAP Authentication using Spring Security? (answer)

This is a very popular Spring Security interview question as Spring provides out of the box support to connect Windows Active Directory for LDAP authentication and with few configurations in Spring config file you can have this feature enabled.

22.  How to implement Role Based Access Control (RBAC) using Spring Security?(answer)

Spring Security provides a couple of ways to implement Role based access control like by using GrantedAuthority. See the article to learn more about it.

These Spring interview Questions and answers are not very difficult and focused on spring fundamentals rather than focusing on an advanced feature of session management, spring security, authentication, etc. we will cover of those question on some other interview article. I would also suggest that share some spring questions asked to you guys during the interview and then I can put together those with their answers for quick reference of everybody.

Other Spring Articles and Interview Questions you may like

How Spring MVC works internally in Java?

10 Things Java Developer should learn in 2018?

5 Spring Boot Features Java Programmer should know

10 Frameworks Java and Web Developer Should learn

Top 5 Spring Microservice Courses for Java developers

3 Best Practices Java Devs can Learn from Spring

10 Tips to become a better Java Programmer in 2018

5 Courses to Learn Spring Boot in 2018

5 Spring Books Experienced  Java Developers Should Read

10 Spring MVC Annotations Java developer should know

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P. S. - If you are preparing for Java Interviews and need more Spring Framework Interview questions for Practice then you can also check out this Spring Framework Interview Guide - 200+ Questions & Answers , which contains 200+ real-world questions and their explanations.