Top 13 Spring Boot Interview Questions

In this tutorial, we'll cover some of the most common questions related to Spring Boot that may come up during a job interview.

1. What Are the Differences Between Spring and Spring Boot?

The Spring Framework provides multiple features that make the development of web applications easier. These features include dependency injection, data binding, aspect-oriented programming, data access, and many more.

Over the years, Spring has been growing more and more complex, and the amount of configuration such application requires can be intimidating. This is where Spring Boot comes in handy – it makes configuring a Spring application a breeze.

Essentially, while Spring is unopinionated, Spring Boot takes an opinionated view of the platform and libraries, letting us get started quickly.

Here are two of the most important benefits Spring Boot brings in:

Auto-configure applications based on the artifacts it finds on the classpath
Provide non-functional features common to applications in production, such as security or health checks. More Additional Info On Spring Boot Online Training

2. How Can We Set up a Spring Boot Application with Maven?

We can include Spring Boot in a Maven project just like we would any other library. However, the best way is to inherit from the spring-boot-starter-parent project and declare dependencies to Spring Boot Starters. Doing this lets our project reuse the default settings of Spring Boot.

3. What is a Spring Framework?

Answer:
Java Spring framework is a lightweight framework, most popular and it is an open-source Java platform. It is a widely used Java EE framework. Spring Framework basically works on two design principles i.e., Dependency Injection and Aspect-Oriented Programming.
The core features of spring are used to in developing any type of Java application easily and rapidly. It promotes good practice on programming by enabling a POJO-based programming model.

4. List some of the important advantages of Spring Framework?

Answer:
This is the basic Java Spring Interview Questions asked in an interview. Java Spring Framework basically works on two design principles i.e., Dependency Injection and Aspect-Oriented Programming.

Below are some of the important features of the Spring Framework:

Lightweight: Java Spring is very lightweight in its size and transparency. It weighs around only 1MB when we consider the basic version of the spring framework. And processing overhead in it is also very negligible.
Inversion of control (IOC): Loose coupling in spring can be achieved by using the technique known as Inversion of Control. In this process, objects give their dependencies instead of creating or looking for dependent objects.
Aspect-oriented (AOP): Java Spring, provides support for situational oriented programming and enables characterized development by separating application business logic from system requirement services.
Container: Java Spring includes and manages the complete lifecycle and configuration of all application objects in the development of a project.
MVC Framework: Java Spring is designed with an MVC web application framework that is built on core Spring functionality. The configuration of this MVC framework is very high and is done by using strategy interfaces, and also provides multiple view technologies like Tiles, JSP, iText, Velocity, and POI.
JDBC Exception Handling: The JDBC layer in the spring helps the error handling strategy by providing an exception hierarchy. By integrating with JDO, Hibernate and iBATIS, Spring provides the best Integration services.
Java Spring framework supports many operations like JDBC operations, transaction management, Exception Handling, File uploading, etc with very minimal configurations.

5. What are Spring sub-projects in Java spring Framework and also describe them in brief?

Answer:

Core – Core is a key module in a framework which provides the fundamental parts of the framework such as IoC or DI.
JDBC – Spring sub-projects module enables a JDBC-abstraction layer which removes the JDBC coding for specific vendor databases for better performances.
ORM integration – This integration facilitates the integration layers for object-relational mapping APIs, such as JDO, JPA and Hibernate features.
Web – For a web-oriented integration module, it provides the features like Servlet listeners, multipart file upload, and context functionalities of web-oriented applications.
MVC framework – This is the implementation of a web module using the Model View Controller design pattern.
AOP module – implementation of object-oriented programming allows defining a clean method-interceptors and pointcuts in the project.

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6. What do you mean by Dependency Injection?

Answer:
Dependency Injection is used as a design pattern and in Spring framework, it provides permission to a web developer to remove the hard-coded dependencies and make the application extendable, loosely coupled and also maintainable. Dependency injection pattern can also be used/implemented to move the dependency resolution from compile-time to runtime.

There are some benefits of using Dependency Injection and they are:

It makes the separation of Concerns,
Allows Boilerplate Code reduction,
Helps in Configurable components and
It is very easy for unit testing.

Java Spring Interview Questions (Advanced)

1. Name some of the important Spring Modules?

Answer
Below is the list some of important Spring Framework modules are:

Spring Context – This module used for the dependency injection process.
Spring AOP – This module helpful for aspect-oriented programming.
Spring DAO – Spring DAO module used for database operations by using DAO pattern
Spring JDBC – Spring JDBC used for JDBC connection and DataSource support.
Spring ORM – This module is important for ORM tools support.
Spring Web Module – Spring Web module is used for creating web applications.
Spring MVC – Spring Model-View-Controller implementation is helpful in developing web applications and web services, etc.

2. How beans are injected in Spring. What is the best way of injecting beans and why?

Answer:
This is the advanced Java Spring Interview Questions asked in an interview. Java Objects which are initialized by Spring IoC container is known as Spring Beans. To get the Spring Bean instance, we use Spring ApplicationContext.

There are only a few different options exist to inject the beans in Spring:

Setter Injection
Constructor Injection
Field Injection

The configuration for this process can be done by using XML files or annotations.

The most common and effective approach for injecting beans is to use constructor arguments. This is used for mandatory dependencies and for optional dependencies we can use setters. The Constructor arguments injection process allows injecting the values to immutable fields and that makes easier for testing.

3. What is Spring Security?

Answer:
Spring Security is considered as a separate module in the Spring framework. It mainly focuses on providing authorization and authentication processes in Java applications. It also handles most of the common security breaches/threats like CSRF attacks.

@EnableWebSecurity is a simple annotation to use Spring Security in web applications.

4. What do you mean by MultipartResolver and when is it used?

Answer:
The MultipartResolver is a strategy interface; it is used for uploading multipart files in a web application.

There are two concrete MultipartResolver are included in Spring:

CommonsMultipartResolver: which is used to Upload Jakarta Commons Files
StandardServletMultipartResolver: It is used for Servlet 3.0 Part multipart request parsing.

5. What is Aspect, Advice, Pointcut, JointPoint and Advice Arguments in AOP?

Answer:

Aspect: Aspect is a category that implements cross-cutting issues, like group action management. Aspects are often a standard category organized then organized in Spring Bean configuration file or we are able to use Spring AspectJ support to declare a category as Aspect using @Aspect annotation.

Advice: recommendation is that the action was taken for a specific be a part of the purpose. In terms of programming, they’re ways that get dead once a particular be a part of purpose with matching pointcut is reached within the application.

Pointcut: Pointcut is regular expressions that are matched with be a part of points to work out whether or not a recommendation has to be dead or not. Pointcut uses completely different forms of expressions that are matched with the be a part of points. Spring framework uses the AspectJ pointcut expression language for crucial the be a part of points wherever recommendation ways are applied.

Join Point: A be a part of the purpose is that the specific purpose of the application like technique execution, exception handling, ever-changing object variable values etc. In Spring AOP a be a part of points is often the execution of a technique.

Advice Arguments: we are able to pass arguments within the recommendation ways. we are able to use args() expression within the pointcut to be applied to any technique that matches the argument pattern. If we tend to use this, then we want to use the constant name within the recommendation technique from wherever argument kind is set.

6. What is a Spring Bean?

Answer:
Any traditional java category that’s initialized by Spring IoC is named Spring Bean. we tend to use Spring ApplicationContext to urge the Spring Bean instance.
Spring IoC manages the life cycle of Spring Bean, bean scopes and injecting any needed dependencies within the bean. Take your career to new heights of success with an Java Spring Boot, enroll for live free demo on Spring Boot Certification

7. Does Spring Bean provide thread safety?

Answer:
The default scope of Spring bean is a singleton, therefore there’ll be only 1 instance per context. which means that everyone the having a category level variable that any thread will update can cause inconsistent information. thus in default mode, spring beans don’t seem to be thread-safe.
However, we are able to modification spring bean scope to request, paradigm or session to attain thread-safety at the value of performance. It’s a design decision and supported the project necessities.

Conclusion

This tutorial went over some of the most critical questions on Spring Boot that you may face during a technical interview. We hope they will help you land your dream job.