Spring Boot Interview Questions For Freshers

Spring Boot Interview Questions: When it comes to Java application development, Spring Boot is the most often discussed topic in interviews. It enables you to construct a stand-alone Java application from the start that is highly durable and maintainable due to its quick, low configuration, inbuilt server, and monitoring capabilities.

The article will lead you through the basic to intermediate-level Spring Boot interview questions.

What is Spring Boot?

Sprint Boot is a Java-based spring framework that is used for Rapid Application Development (the creation of stand-alone microservices).

It also supports auto-configuration and embedded application servers such as Tomcat, Jetty, and others.

What Distinguishes the Spring Boot From Others?

Creates a self-contained spring application with few settings.
It includes Tomcat and Jetty, allowing it to simply develop and run the application.
Provide features that are ready for production, such as metrics, health checks, and externalized configuration.
There is no demand for XML setup.

Spring Boot Interview Questions For Freshers

Below are the Spring Boot Interview Questions for Freshers:

1. What are the merits of using Spring Boot?

The following are the benefits of Spring Boot:

Spring apps are simple to comprehend and construct.
Spring Boot is nothing more than an existing framework with the addition of an integrated HTTP server and annotation settings to make development easier to grasp and faster.
Increases productivity while decreasing development time.
The most basic arrangement.
We don’t need to create any XML configuration; all we need are a few annotations to complete the configuration.

2. What are the key elements of Spring Boot?

The four key components of a spring boot are as follows:

Spring Boot Actuators.
Spring Boot auto-configuration.
Spring Boot CLI.
Spring Boot starter POMs.

3. What is the advantage of Spring Boot over Spring?

Here are some key differences between spring boot and spring:

Actuators
Auto Configuration.
Component Scanning.
Embedded server.
InMemory DB.
Starter POM.
Version Management.

4. What is the starter dependency of the Spring boot module?

Spring boot provides a good numbers of starter dependency. However, here are the most commonly used:

Data JPA starter.
Mail starter.
Security starter.
Test Starter.
Thymeleaf starter.
Web starter.

5. How does Spring Boot works?

Spring Boot configures your application automatically depending on the dependencies you have introduced to the project via annotation.

The class with the @SpringBootApplication annotation and the main function is the spring boot application’s entry point.

By utilising the @ComponentScan annotation, Spring Boot automatically scans all of the project’s components.

6. What does the @SpringBootApplication annotation do internally?

The @SpringBootApplication annotation is comparable to utilizing the default properties of @Configuration, @EnableAutoConfiguration, and @ComponentScan.

Spring Boot allows developers to utilise a single annotation rather than several annotations. However, as we know, Spring provides loosely coupled features that we can use for each annotation based on the needs of our project.

7. What is the purpose of using @ComponentScan in the class files?

When the Spring Boot application starts, it scans all the beans and package declarations. To scan the components added to your project, you must add the @ComponentScan annotation to your class file.

8. How is a Spring Boot application launched?

A Spring Boot application, like any other Java programme, must have a main function. This method acts as an entry point for the application, invoking the SpringApplication#run function to boot it up.

9. What are starter dependencies?

Spring boot starter is a maven template that includes a collection of all the essential transitive dependencies required to launch a certain capability.

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10. What is Spring Initializer?

Spring Initializer is an online tool that assists you in creating an initial spring boot project structure and gives a maven or gradle file from which you may build your code.

It overcomes the difficulty of establishing a framework when beginning a new project from scratch.

11. What is Spring Boot CLI and what are its benefits?

Spring Boot CLI is a command-line interface that allows you to use Groovy to develop a spring-based java application.

You do not need to define getter and setter methods, access modifiers, or return statements, for example. If you use the JDBC template, it will load automatically.

12. What are the most common Spring Boot CLI commands?

-run, -test, -grap, -jar, -war, -install, -uninstall, –init, -shell, -help.

To check the description, run spring –help from the terminal.

Advanced Spring Boot Questions

Below are more advance Spring Boot Questions:

13. What Are the Basic Annotations that Spring Boot Offers?

The main annotations that Spring Boot offers reside in its org.springframework.boot.autoconfigure and its sub-packages. However, here are a couple of basic ones:

@SpringBootApplication – used to denote the main class of a Boot Application. This annotation combines @Configuration, @EnableAutoConfiguration, and @ComponentScan annotations with their default attributes.
@EnableAutoConfiguration – to ensure that Spring Boot looks for auto-configuration beans on its classpath and automatically apply them.

14. What is Spring Boot dependency management?

Spring Boot dependency management is used to automatically manage dependencies and settings without requiring you to declare the version for any of those dependencies.

15. Can we use Spring Boot to construct a non-web application?

Yes, by removing the web dependencies from the classpath and changing the way Spring Boot creates the application context, we can create a non-web application.

16. Can the integrated Tomcat server’s port be changed in Spring Boot?

Yes, that is conceivable. Using the server.port property in application.properties.

17. What is Tomcat’s default port in Spring Boot?

The Tomcat server-id’s default port is 8080. It is possible to update it by including sever.port properties in the application.property file.

18. In Spring Boot, can we override or replace the Embedded Tomcat server?

Yes, we can use the Starter dependency in the pom.xml file to replace the Embedded Tomcat server with any server. For example, if you want to utilise a jetty server in your project, you may add spring-boot-starter-jetty as a dependent.

19. Is it possible to turn off the default web server in the Spring startup application?

Yes, we can configure the web application type using application.properties, e.g. spring.main.web-application-type=none.

20. How do I disable a certain auto-configuration class?

If you don’t want auto-configuration to apply to a certain class, use the exclude parameter of @EnableAutoConfiguration.

21. Explain @RestController annotation in Sprint boot?

It is a mix of @Controller and @ResponseBody that is used to create a restful controller. It transforms the response into JSON or XML. It guarantees that the data supplied by each method is put directly into the response body rather than returning a template.

22. In Spring Boot, what is the difference between @RestController and @Controller?

@Controller maps the model object to a view or template and makes it human readable, whereas @RestController merely returns the object, with the object contents immediately published in the HTTP response as JSON or XML.

23. Can you describe how HTTPS requests travel via the Spring Boot application?

Follow the MVC pattern in a high-level spring boot application.

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24. What’s the distinction between RequestMapping and GetMapping?

Using the method property on the annotation, RequestMapping may be used with GET, POST, PUT, and many more request methods. Whereas getMapping is simply an extension of RequestMapping that helps you improve request clarity.

25. What role do Profiles play in spring boot?

We deal with many environments while creating the application, such as dev, QA, and Prod, and each environment demands a distinct setup.

For example, we may use an integrated H2 database for development but a commercial Oracle or DB2 database for production. Even though the DBMS is the same throughout the environment, the URLs will change.

Spring offers the Profiles feature to maintain the independent setting of environments simple and clear.

26. What exactly is a Spring Actuator? What are its benefits?

An actuator is a Spring feature that allows you to monitor and control your application after it has been deployed to production. Auditing, health, CPU use, HTTP hits, and metric collecting are just a few of the actuators that are automatically applied to your programme.

27. How do I activate Actuator in a Spring Boot application?

To activate the spring actuator functionality, we must include the “spring-boot-starter-actuator” dependency in pom.xml.

28. What are the endpoints offered by the actuators that are used to monitor the Spring boot application?

Actuators give the pre-defined endpoints listed below to monitor our application:

Beans
Configprops
Health
Heapdump
Httptrace
Info
Mappings
Shutdown
Threaddump

29. How do you get a list of all the beans in your Spring Boot app?

The Spring Boot actuator “/Beans” returns a list of all spring beans in your application.

30. How do you examine the environment attributes in your Spring Boot application?

Spring Boot actuator “/env” gives a list of all the environment properties of the spring boot application that is currently executing.

31. How can I activate the spring boot application’s debugging log?

There are three ways to activate debugging logs:

With the –debug switch, we can run the application.
In the application.property file, we may set the logging.level.root=debug property.
In the supplied logging configuration file, we can set the root logger’s logging level to debug.

32. In the Spring Boot application, where do we define properties?

In a file called application.properties, you can define both application and Spring boot-related properties.

This file may be created manually or by using Spring Initializer. You don’t need to do anything specific to tell Spring Boot to load this file.

If it’s in the classpath, Spring Boot will load it and configure itself and the application code accordingly.

33. What is dependency injection?

Dependency injection refers to the technique of injecting dependent bean objects into target bean objects.

Setter Injection: By executing the setter method, the IOC container will inject the dependent bean object into the target bean object.
Constructor Injection: By executing the target bean constructor, the IOC container will inject the dependent bean object into the target bean object.
Field Injection: Using the Reflection API, the IOC container will inject the dependent bean object into the target bean object.

34. What is an IOC container?

The IoC Container framework is used to create automated dependency injection. It handles object creation and lifetime, as well as injecting dependencies into the class.

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What is Spring Boot?

What Distinguishes the Spring Boot From Others?