Spring Boot Interview Questions For Experienced Professionals

You Want To Make Your Application Configurable Say Specify A Different Database Connection For Development And Production Environments What Are Your Options

By default, Spring Boot pulls in properties from almost 20 locations, from environment variables and command-line arguments to configuration files .These locations are also ordered, so that the locations lower in the list, override earlier ones. You can, for example, put a default application.properties inside your deployable .jar file, whereas your ops colleagues only override some of them by supplying their own application.properties file on the deployment machine.

It is essential to understand these locations and the default behavior, as to not re-implement Spring Bootâs properties functionality with a custom PropertySourceProvider or use more heavyweight options like spring-cloud configuration server.

You also need to make sure to understand Springâs relaxed properties binding concept, in that you can bind properties from those locations to configuration bean properties, without an explicit name match.

Which Transaction Management Type Is More Preferable

Most users of the Spring Framework choose declarative transaction management because it is the option with the least impact on application code, and hence is most consistent with the ideals of a non-invasive lightweight container. Declarative transaction management is preferable over programmatic transaction management though it is less flexible than programmatic transaction management, which allows you to control transactions through your code.

Explain The Bean Scopes Supported By Spring

There are five scopes provided by the Spring Framework supports following five scopes:

The default scope of a Spring Bean is Singleton.

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What Is A Spring Bean

A class which contains attributes and methods with business logic to perform some processing and its object is instantiated, assembled and otherwise managed by a Spring IoC container is called a Spring Bean. There is no restriction for creating spring beans. It can refer to any third party interface/class/annotation.

Why Did You Use Spring Boot In Your Application

As discussed earlier, Spring boot makes it easier for you to create Spring application, it can save a lot of time and efforts.

For example: Lets say you want to create Spring boot project with activeMQ. You can simply use “springbootstarteractivemq” as artifact Id, it will take all the defaults and create Spring application with ActiveMQ configured. Lets say you dont want to use inbuilt activeMQ, you can simply override “spring.activemq.broker-url” in application.properties to use external ActiveMQ.

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Can You List Advantages Of Spring Boot

Advantages of Spring boot are:

• It provides a lot of default configurations which help you to create Spring application faster.
• It comes with embedded tomcat or jetty server, so you dont have to deploy jar.
• It reduces development code by avoiding a lot of boilerplate code.
• It increases productivity as you can create Spring application quickly.
• It provides a lot of starter project for easy maven integration.You dont have to worry about version mismatch.
• You can quickly create using sample project using spring boot initializer

Describe The Flow Of Https Request Through The Spring Boot App

We all can see the above image of the spring boot flow architecture to understand the basic concept of the HTTPS request flow in the spring boot app.

We have the validator classes, view classes, and utility classes.

As we all know, spring boot uses the modules of spring-like MVC, spring data, etc.

So the concept also the same for several things, and also the architecture of spring boot is the same as the architecture of spring MVC instead of one concept, there is no need for the DAO and DAOimpl classes in spring boot.

It creates a data access layer and started performing CRUD operations.

CRUD operation is nothing but Create Read Update and Delete operation, which is done by all of the programmers in their website.

The client makes the HTTP request in PUT or GET.

After this, the request goes to the controller, and the controller maps that respective request and handles it if there is the requirement for calling some logic, it calls the service logic after handling the request.

All the business logic performs in the service layer.

Service layer performs the logic on the data that is mapped to JPA with model classes.

A JSP page is returned to the user if no error has occurred.

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What Is The Use Of Profiles In Spring Boot

While developing the application we deal with multiple environments such as dev, QA, Prod, and each environment requires a different configuration. For eg., we might be using an embedded H2 database for dev but for prod, we might have proprietary Oracle or DB2. Even if DBMS is the same across the environment, the URLs will be different.

To make this easy and clean, Spring has the provision of Profiles to keep the separate configuration of environments.

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Faqs On Spring Boot Interview Questions

Q1. Why is it important to practice Java Spring Boot interview questions for technical interviews?

Knowing your way around Java Spring Boot is important because FAANG+ companies often test your knowledge of popular Java frameworks and Microservices in coding and design rounds of technical interviews.

Q2. What is the primary use of the Spring Boot tool when working with the Spring framework?

The Spring Boot tool is used mainly to configure Rest APIs and enhance the performance of applications created using Spring.

Q3. Are Spring Boot interview questions asked at Java fresher interviews?

If youâre a fresher, youâre not necessarily expected to know the functioning of various Java Microservices tools and frameworks. Thus, Spring Boot interview questions are mostly asked at interviews for experienced developers.

Q4. What are the minimum requirements for a Spring Boot system?

For Spring Boot to function correctly, the following system requirements are necessary: Java version – Java8+, Java Spring 5.1.9, Maven 3.3+ , Gradle 4.4+ , Jetty 9.4 , Undertow 2.0 .

Q5. Is Java Spring Boot used for front-end development?

Java Spring Boot is mainly used to support the backend or server-side of Microservices applications built using the Spring framework.

Q43 Why Is Spring Data Rest Not Recommended In Real

Spring Data REST is not recommended in real-world applications as you are exposing your database entities directly as REST Services. While designing RESTful services, the two most important things that we consider is the domain model and the consumers. But, while using Spring Data REST, none of these parameters are considered. The entities are directly exposed. So, I would just say, you can use Spring Data REST, for the initial evolution of the project.

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What Is The Major Advantage Of The Yaml File How Do You Upload The Yaml File To Spring Boot

The major advantage of YAML is it is easier to debug issues since data is stored in a hierarchical format. We can upload the YAML file to Spring Boot by using the methods mentioned below:

• To load YAML as a map – we need to use YamlMapFactoryBean
• To load YAML as properties – we need to use YamlPropertiesFactoryBean

How To Handle 404 Error In Spring Boot

Consider a scenario, where there are no stockDetails in the DB and still, whenever you hit the GET method you get 200 even though the resource is not found which is not expected. Instead of 200, you should get 404 error.So to handle this, you need to create an exception, in the above scenario StockNotFoundException.

GetMapping  public Stock retriveStock    

Now, create a Constructor from Superclass.

Right-click on the file -> Go to Source -> And generate constuctors from superclass-> and check the RuntimeException-> and generate.

And add an annotation called which will give you 404 error.

Now, you can hit the same URL again and there you go, you get a 404 error when a resource is not found.

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What Is Devtools In Spring Boot

Spring boot comes with DevTools which is introduced to increase the productivity of developer. You dont need to redeploy your application every time you make the changes.Developer can simply reload the changes without restart of the server. It avoids pain of redeploying application every time when you make any change. This module will be disabled in production environment.

What Is Ioc Container

IoC Container is a container of Spring Beans. The main objective of this container is to create the objects, wire them together, configure and manage their complete life cycle from creation till destruction. We provide Spring Beans and some configuration metadata to the IoC container. IoC container reads the configuration metadata, wire the beans each other and manage beans lifecycle accordingly and provide us fully configured system.

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Is The Following Statement True Or False: Every Spring Boot Application Is A Web Application Running Within An Embedded Apache Tomcat Give Reasons For Your Answer

The statement is false.

When it comes to web applications, Spring Boot works with a variety of servlet containers. The default one is Apache Tomcat, but you can also use it with Jetty, Undertow, or without an embedded servlet container at all.

Whatâs more, Spring Boot isnât tied to just web applications, though one might get that impression by using the spring-boot-starter-web dependency and thus Spring Bootâs web autoconfiguration. You can write all kinds of services with it, from batch jobs and command-line services, over to messaging backends and reactive web applications.

What Do You Mean By Aop

• Before: These are types of advices, which get executed before the join point methods and can be configured using @Before annotation mark.
• After returning: These are the types of advices which get executed after the join point methods completes executing and the annotation mark used to configure it is @AfterReturning
• After throwing: These are the types of advices that execute only and only if join point method returns by exiting an exception and annotation mark used to configure it is @AfterThrowing.
• After : These are the types of advices which gets executed after a join point method, not concerning whether the methods exit normally or exceptional return and it can be configured using @After annotation mark.
• Around: These are the types of advices that get executed before and after a join point and can be configured using the @Around annotation mark.

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What Are The Different Types Of Ioc

What Is The Open

The Open-Closed Principle is one of the SOLID design principles. SOLID contains five principles which were described by Robert C Martin. SOLID stands for

The openclosed principle states that “Software entities should be open for extension, but closed for modification“. Means, such an entity can allow its behaviour to be extended without modifying its source code. In the above code, we have seen how we have implemented this principle by using interfaces.

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How Do You Define The Scope Of A Bean

When defining an in Spring, we can also declare a scope for the bean. It can be defined through the scope attribute in the bean definition. For example, when Spring has to produce a new bean instance each time one is needed, the beans scope attribute to be a prototype. On the other hand, when the same instance of a bean must be returned by Spring every time it is needed, the bean scope attribute must be set to a singleton.

Can We Change The Port Of The Embedded Tomcat Server In Spring Boot

Yes, you can change the port of embedded Tomcat server in Spring boot by adding the following property in your application.properties file.

server.port=8084

The default port number of the tomcat server to run the spring boot application is 8080, which is further possible to change it.

So we can change the port of tomcat following ways given below:-

• Using application.properties

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Q20 Why Do We Need Spring Profiles

When developing applications for the enterprise, we typically deal with multiple environments such as Dev, QA and Prod. The configuration properties for these environments are different.

For example, we might be using an embedded H2 database for Dev, but Prod could have the proprietary Oracle or DB2. Even if the DBMS is the same across environments, the URLs would definitely be different.

To make this easy and clean, Spring has the provision of profiles to help separate the configuration for each environment. So, instead of maintaining this programmatically, the properties can be kept in separate files such as application-dev.properties and application-prod.properties. The default application.properties points to the currently active profile using spring.profiles.active so that the correct configuration is picked up.

gives a comprehensive view of this topic.

Explain The Web Module

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.

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Q44 What Is The Error You See If H2 Is Not In The Classpath

If H2 is not present in the classpath, then you see the following error:

Cannot determine embedded database driver class for database type NONE

To resolve this error, add H2 to the pom.xml file, and restart your server. The following code snippet can be added to add the dependency:

< dependency> < groupId> com.h2database< /groupId> < artifactId> h2< /artifactId> < scope> runtime< /scope> < /dependency> 

How To Use Thymeleaf

Steps are as follows:

For Gradle:

implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'implementation 'org.springframework.boot:spring-boot-starter-web'

For Maven:

< dependency> < groupId> org.springframework.boot< /groupId> < artifactId> spring-boot-starter-thymeleaf< /artifactId> < /dependency> < dependency> < groupId> org.springframework.boot< /groupId> < artifactId> spring-boot-starter-web< /artifactId> < /dependency> 

DemoController.java:

< !DOCTYPE html> < html xmlns:th="http://www.thymeleaf.org"> < head> < meta http-equiv="Content-Type" content="text/html  charset=UTF-8" /> < title>  Thymeleaf Spring Boot Demo < /title> < /head> < body> < p th:text=" 'Hello, ' + $ + '!'"/> < h4>  Welcome to Thymeleaf Demo in Spring Boot< /h4> < /body> < /html> 

Run the application using Integrated Development Environment: Run as -> Spring Boot App.

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Spring Boot Interview Question Answer For Java Developers

1. What is Spring Boot? Why should you use it?you don’t need to setup a Tomcat server2. What are some important features of using Spring Boot?1. Starter dependencyRESTful services2. Auto-Configuration3. Spring Initializer4. Spring Actuator5. Spring CLILearn Spring Boot – Rapid Spring Application Development3. What is auto-configuration in Spring boot? how does it help? Why Spring Boot is called opinionated?Spring Security MasterclassLearn Spring 5 and Spring Boot 2 courses4. What is starter dependency in Spring Boot? how does it help?Spring MVCJackson6. What is Spring Initializer? why should you use it?Spring Boot Masterclass.7. What is Spring Actuator? What are its advantages?beansCPU and memory usageSpring Security Certification Class8. What is Spring Boot CLI? What are its benefits?Spring Boot in Action9. Where do you define properties in Spring Boot application?10. Can you change the port of the Embedded Tomcat server in Spring boot? If Yes, How?Learn Spring Boot in 100 Steps 11. What is the difference between an embedded container and a WAR?web server12. What embedded containers does Spring Boot support?13. What are some common Spring Boot annotations?Main class14. Can you name some common Spring Boot Starter POMs?15. Can you control logging with Spring Boot? How?classpathcommon Spring Boot Interview Questions for Java developersSpring Framework Interview Questions

What Are The Limitations Of Java Ee

Connectioncon=DriverManager.getConnection Statementst=con.createStatement ResultSetrs=st.executeQuery while) 

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