Latest Spring Common Interview Questions and Answers Collection: Interview Essentials

Since its release in October 2002, Spring Framework has managed to become a top application framework for Java developers. In fact, it has a place among the leading back-end web development frameworks. As a result, choosing a career in the Spring Framework is very lucrative.

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A collection of popular Spring common interview questions and answers

Spring Framework has a broad range of concepts that require a deep understanding of these concepts to stay ahead of the game and stay ahead of the game. If you are preparing for a Spring job interview, then here are the answers to the top Spring interview questions you must know:

Question: Please list the various features of the Spring Framework and the advantages of using them.

The Spring interview questions are broken down as follows:

Features of the Spring Framework:

Allows you to create and manage the configuration and lifecycle of application objects
Aspect Oriented Programming (AOP) supports unified development by separating application business logic from system services
Highly configurable MVC web application framework with the ability to easily switch to other frameworks
Instead of finding or creating dependencies, objects provide their dependencies. This design principle is known as IoC (Inversion of Control)
Light
Provides a common abstraction layer for transaction management and can also be used in containerless environments
The JDBC abstraction layer provides an exception hierarchy that simplifies error handling

Advantage:

Enable POJO (Plain Old Java Object) programming to further enable continuous integration and testability
Open source with no vendor lock-in
JDBC simplified due to DI (dependency injection) and inversion of control
Thanks to the layered architecture, it’s easy to keep what you need and discard what you don’t

What are the common Spring interview questions: How many modules does Spring Framework have?

A: The Spring Framework has about 20 modules. Each of them is divided into one of the following layers:

Spring Core Container – The basic core layer of the Spring Framework. It has the following modules:
SpEL (Spring Expression Language)
Spring Bean
Spring Core
Spring Context
Data Access/Integration – This is the layer responsible for providing support for interacting with the database. It contains the following modules:
JDBC (Java Database Connection)
JMS (Java Message Service)
ORM (Object-Relational Mapping)
OXM (Object XML Mapper)
trade
Web – It is the responsibility of this layer to provide support for the creation of web applications. It has these modules:
Web
Web – MVC
Web – Portlet
Web – Socket
Aspect-oriented programming – allows for decoupling code with suggestions, entry points, etc
Instrumentation – Provides support for class detection and classloader implementations
Testing – Responsible for supporting the completion of tests with JUnit and TestNG

Some of the additional Spring Framework modules are:

Aspects – Provides support for integration with AspectJ
Messaging – Provides support for STOMP and the annotation programming model for processing and routing STOMP messages from WebSocket clients

Question: What are the components of a Spring application?

Spring Interview Questions Explained: A typical Spring application can be broken down into the following components:

Bean Classes – Contains properties, functions, setters, getter methods, etc
Bean Configuration File – Contains information about the class and how to configure it
Interface – Define the function
Spring Aspect Oriented Programming – Provides the ability to cross-cut concerns
User Programs – Use Functions

Question: What is your understanding of Spring IoC Container? Explain their types.

A: Spring IoC containers are at the heart of the Spring Framework. Containers use dependency injection to manage a variety of Spring application components.

IoC containers are responsible for creating objects, configuring them, connecting them together, and managing their lifecycles. The container receives instructions about the same from the provided configuration metadata.

Methods that provide configuration metadata can include Java comments, Java code, or XML. There are two types of IoC containers in Spring:

ApplicationContext – Provides additional functionality. It’s built on top of the BeanFactory interface.
BeanFactory – A pre-packaged class containing a collection of beans. Instantiate beans based on customer requirements

Spring Common Interview Questions and Answers: Please explain the dependency injection in Spring. How many ways can I use the same method?

Answer: Dependency injection allows you to define how an object should be created, rather than creating it directly. As a result, the code does not directly involve connecting components and services together.

The configuration file contains information about which components require which services. IoC containers are responsible for connecting components with appropriate services. Dependency injection can be used in the following forms:

Constructor injection
setter injection

Question: Can you tell the difference between an ApplicationContext and a BeanFactory in Spring?

Reply:

Annotation-based dependencies – BeanFactory does not support annotation-based dependencies, whereas ApplicationContext does
Interface Definition – The BeanFactory interface is defined in org.springframework.beans.factory.BeanFactory, while the ApplicationContext interface is defined in org.springframework.context.ApplicationContext
Internationalization support – While ApplicationContext supports internationalization, BeanFactory does not
Object Management – BeanFactory uses syntax to provide resource objects. Instead, the ApplicationContext creates and manages resource objects on its own
Initialization type – ApplicationContext uses urgent or aggressive initialization. BeanFactory, on the other hand, uses lazy initialization

Question: How is configuration metadata provided to the Spring container?

Answer: There are three ways to configure metadata to be provided to Spring containers, which are listed below:

Annotation-based configuration – By default, annotation connections in Spring containers are turned off. The use of annotations on the applicable class, field, or method declaration allows it to override the use of XML to describe bean connections.
Java-based configuration – this is the latest form of configuration metadata in the Spring Framework. It has two important components:
1. @Bean annotation – Same as the <bean/> element
2. @Configuration annotations – allows you to define dependencies between beans by simply calling other @Bean methods in the same @Configuration class
XML-based configuration – The dependencies and the services required by the bean are specified in the configuration file that follows the XML format. Typically, these profiles contain several application-specific configuration options and bean definitions.

Question: What is your understanding of Spring Beans? How many bean scopes does Spring Framework support?

A: Spring Beans that are configured, instantiated, managed, and connected by Spring IoC containers are the objects that form the core of Spring applications. Spring Beans are created using configuration metadata provided to Spring IoC containers.

Spring Framework provides support for a total of 5 scopes:

Global Session* – Provides bean-defined scopes for global HTTP sessions
Prototype – Provides scope for a single bean definition with any number of object instances
Request* – Provides a bean-defined scope for HTTP requests
Session* – Provides a bean-defined scope for a single instance of each Spring IoC container
Singleton – Provide bean-defined scopes for a single instance of each Spring IoC container *? Available only when using a web-aware ApplicationContext.

Question: Can you explain the bean lifecycle in the Spring Bean Factory Container?

Reply:

The bean lifecycle begins with a Spring IoC container instantiating a bean from a bean definition in an XML file
As specified in the bean definition, Spring then populates all properties with DI
If the bean implements the BeanNameAware interface, the setBeanName() method is called by passing the bean ID
If the bean implements the BeanFactoryAware interface, the setBeanFactory() method is called by passing an instance of the bean
If there are any BeanPostProcessors associated with the bean, the preProcessBeforeInitialization() method is called
If the bean is specified with the init method, the method is called
Finally, if there are any BeanPostProcessors associated with the bean, the postProcessAfterInitialization() method is called.

Question: What is a Spring configuration file?

A: Since Spring is based on the concept of dependency injection, all classes, interfaces, and their dependencies are stored in a file called a spring configuration file. It is an .xml file. The Spring container uses this file to control the lifecycle of the Spring Bean. A bean is configured as:

<bean id = "..." class = "..." init-method = "..." lazy-init="true" destroy-method="....">
      <!-- bean dependencies and configurations -->
</bean>

What are the Common Spring Interview Questions: What Are the Benefits of IoC (Inversion of Control)?

A: The advantages are:

There’s no need to write a lot of code on how to create services and get object references. Everything can be achieved with simple configuration. Simply add a constructor or setter method to add new dependencies and services.
The code is easier to unit test because it is designed as multiple components where developers can inject their objects and switch implementations.
Loose coupling of components.
Allows lazy loading of objects and dependencies.

Q: What is the bean lifecycle in Spring Bean Factory Container?

A: The life cycle of a bean is as follows:

Beans are instantiated by Spring containers based on the bean definitions in the spring configuration file.
With dependency injection, all properties specified in the bean definition are populated.
If the bean implements the BeanNameAware interface, the bean factory calls setBeanName() bypassing the bean’s ID.
If the bean implements the BeanNameAware interface, setBeanFactory() is called by passing the bean’s instance.
If any BeanPreProcessor is associated with a bean, the preProcessBeforeInitialization() method is called.
The initialization method, if defined for the bean, will be called.
Finally, the postProcessAfterInitialization() method is called if needed.

Question: Explain the inner beans in Spring.

A: An inner bean is a bean that exists within the scope of another bean. The concept is similar to an internal class in Java. An internal bean is defined as a target within an external bean ID tag.

<bean id = "outerBean" class = "...">
      <property name = "target">
         <bean id = "innerBean" class = "..."/>
      </property>
</bean>

Question: What is annotation-based container configuration? Also, explain how to open annotation links in the Spring Framework.

A: Annotation-based container configuration is an alternative to XML setup. Instead of using XML to describe bean connections, developers move configuration to component classes by using comments on the appropriate class, field, or method declarations.

Because annotation connections are turned off by default, they need to be turned on before they can be used. It is done by configuring the <context:annotation-config/> element in the Spring configuration file.

Q: Please explain the various annotations that Spring supports.

Reply:

@Autowired – Used to automatically assemble beans on setter methods, properties, constructors, or methods with arbitrary names or multiple parameters. It allows precise control of how and where the automatic assembly is carried out.
@Component – Spring manages the generic stereotype of a component that marks Java classes as beans that can be picked up by the component scanning mechanism and pulled into the context of the application.
@Controller – Marks the class as a Spring Web MVC controller. Beans marked with this annotation are automatically imported into the dependency injection container.
@Qualifier – Used with @Autowired annotations to specify one of only a few but similar beans that need to be connected.
@Repository – Specialization of component annotations with almost the same purpose and function. Specifically, it provides additional benefits to DAOs (Data Access Objects).
@RequestMapping – Maps a specific HTTP request method to a specific class or method in the controller that is responsible for handling the corresponding request.
@Required – Applied to the bean property setter method, it represents the need to populate the bean property at configuration time with explicit attribute values present in the bean definition or through automatic assembly. If the bean property is not populated, the container throws a BeanInitializationException message.
@Service – Another specialization of component annotations. Although it doesn’t provide any extra behavior beyond component annotations, it can be used for @component annotations in service layer classes to specify intents in a better way.

Q: What does Spring DAO support mean?

A: Spring DAO support simplifies the use of data access technologies such as JDBC, JDO, and Hibernate in a reliable way. In addition, it allows coding without worrying about catching specific technical exceptions, and it is easy to switch between persistence techniques.

Question: What classes are included in the JDBC API?

Reply:

Database templates
Name the Jdbc template
Simple JdbcCall
Simple Jdbc insertion
Simple Jdbc template

Question: How will you use the Spring Framework to access Hibernate?

A: There are two ways to access Hibernate using the Spring Framework:

Extend the Hibernate DAOSupport, and then apply the AOP interceptor node
Use Hibernate templates and callbacks for inversion of control

A collection of common Spring interview questions and answers: List the types of transaction management supported by Spring.

A: Spring Framework supports two types of transaction management:

Declarative transaction management – While transaction management is decoupled from business code, transactions are managed using only comments or XML-based configurations.
Programmatic transaction management – Transactions are managed programmatically. Although extremely flexible, it is very difficult to maintain.

Q: Please explain the AOP technique.

A: AOP, or Aspect Oriented Programming, is a programming technique that allows programmers to modularize behaviors that span typical division of duties or cross-cutting concerns. Logging and transaction management are examples of cross-cutting concerns.

Question: What is Spring’s suggestion? Explain its various types.

A: Any action taken by an aspect at a particular connection point in the Spring framework is called an Advice. Spring AOP uses notifications to maintain a chain of interceptors “around” connection points, i.e., as interceptors. Recommendations can be of the following types:

After (finally) – Executes after the joinpoint method using the @After annotation tag configuration, either exiting normally or throwing an exception
After returning – using the @AfterReturning annotation tag configuration, it is executed as soon as the joinpoint method completes normal execution
Post-Throw – Configured with @AfterThrowing annotation tags, executed if and only if the joint point method exits by throwing an exception
Around – Configured with @Around annotation tags, which are executed before and after the connection point method
Before – Configured with @Before annotation tags, executed before the joinpoint method

Question: Can you compare the concerns and cross-cutting concerns in Spring AOP?

Spring Interview Question Analysis: While concerns are the behaviors that developers want to have in a particular module of a Spring application, cross-cutting concerns are concerns that apply to the Spring application as a whole.

Question: What is your understanding of the Spring MVC framework?

A: The Spring MVC framework provides a model-view-controller architecture and ready-to-use components for developing flexible, loosely coupled Web applications.

In addition to providing loose coupling between these decoupled elements, the MVC pattern also helps to separate aspects of the application, such as business logic, input logic, and UI logic.

Question: Please explain the DispatcherServlet.

A: The DispatcherServlet is the essence of the Spring Web MVC framework, handling all HTTP requests and responses. The DispatcherServlet forwards the request to the controller after receiving the ingress of the handler mapping from the configuration file.

After that, the controller returns a model and view object. After that, the Dispatcher servlet checks if there is a portal for the view parser in the configuration file and calls the specified view component.

Q: What is Spring?

A: Spring is an integration framework for developing enterprise applications in Java.

Question: Is there any difference between a Bean Factory and an Application Context?

A: Yes, there are many differences between Bean Factory and Application Context. These instructions are as follows:

Bean Factory	Application Context
This is a basic container	It is a high-level container
It has a limited interface.	It extends the Bean Factory interface
It offers a variety of infrastructures.	It offers additional features over Bean Factory, including integration with Spring AOP, i18n’s message resource handling, and more.

What are the Common Spring Interview Questions: What is the difference between Constructor Injection and Setter Injection?

A: The differences between Constructor Injection and Setter Injection are as follows:

Constructor injection	Setter injections
It has a full injection	It has a partial injection
It doesn’t override the setter property	When they are all defined, it overrides the constructor properties.
When modifications are needed, it creates a new instance.	When a property value changes, it doesn’t create a new instance.
It has more properties than Setter Injection	This is good for some properties.

Question: Is Autowriting defined in Spring?

A: Auto-assembly in Spring helps computer programmers apply beans automatically without having to write explicit injection logic. The various autowrite modes include the following.

NO。
By name.
By type.
Constructor.

Question: What are the different types of bean scopes in the Spring Framework?

A: There are five main types of bean scopes in the Spring Framework. These include the following:

Singleton.
Prototype.
request。
session。
Global session.

Question: What is the entry point in Spring?

A: Pointcut is an expression language of Spring AOP.

What are the different latest versions of the Spring Framework?

The latest version of the Spring Framework is as follows.

Spring 2.5
Spring 3.0
Spring 4.0

Question: What is JoinPoint?

A: A JoinPoint is a point in the execution of a program that represents the execution of a method. It includes the execution of methods and even the handling of exceptions.

Q: What is the difference between Spring AOP and AspectJ AOP?

A: There are several differences between Spring AOP and AspectJ AOP, which are as follows:

Spring AOP	AspectJ AOP
Agents are done by runtime weaving.	Compile-time weaving is done through the AspectJ Java tool
A method-level entry point is applied	A field-level entry point is applied
It is based on DTD	It is configured based on schemas and annotations

Question: What is a proxy in the Spring Framework?

A: Proxies in the Spring framework are known as creating objects after a notification has been applied to a specific target object.

Question: When is the target object the same as the proxy object?

A: In the case of client objects, the target object and the proxy object are the same.

Question: What is weaving in the Spring framework?

A: Weaving in the Spring framework is the process of linking specific aspects with other application types or objects in order to create a suggestion object. It is mainly executed at runtime.

Question: What is Spring Security?

A: Spring Security is a stand-alone module within the Spring Framework that focuses on providing authentication and authorization methods that can be used in Java applications.

Question: What is Spring Boot?

A: Spring Boot is the name of a project that provides a set of pre-configured frameworks designed to reduce boilerplate configurations. It helps to get Spring applications up and running with less code.

Question: What is reactive programming?

A: Reactive programming is a non-blocking and event-driven application. It scales with a small number of threads. Back pressure is the key factor, which determines that the producer will not overwhelm the consumer.

Question: What are the benefits of reactive programming?

A: There are several benefits to reactive programming, including the following.

It helps improve the utilization of computing resources, including multi-core and multi-CPU hardware.
It helps to improve performance by reducing the serialization process.

Question: What are the important features of the Reactive system?

A: Important features of the Reactive system include the following.

Message-driven.
Resilient.
Responsive.
Elasticity.

Question: What is Spring Webflux?

A: Spring Web Flux is a highly responsive web framework for Spring. It acts as an alternative to Spring MVC and provides a highly scalable and non-blocking stack.

Spring Common Interview Questions and Answers Collection: Define Mono and Flux Types?

A: Mono and Flux types, both of which are Spring Framework 5 reactors. Mono represents a single asynchronous value, while Flux represents a stream of asynchronous values. Together, they help implement a publisher interface that is clearly defined in the Reactive Flow specification.

Question: What is the basic difference between Mono and Flux in Spring?

A: Mono implements the publisher and returns 0 or even 1 element, while Flux implements the publisher and returns N elements.

Q: What do Mono and Flux have in common?

A: Common features of Mono and Flux include the following.

They represent streams.
You can’t execute streams without consuming them using the subscribe method.
They are immutable and can be called again and again to create a new instance of Flux or Mono.

Q: What is the difference between a web client and a Webtestclient?

Spring Interview Questions Analysis: The differences between the web client and the Webtest client are as follows.

Web client	Network test client
The web client acts as a reactive client that executes non-blocking HTTP requests.	Webtestclient also acts as a reactive client that can be used for testing.
It can handle reacting flows with back pressure.	It can be bound directly to the WebFlux application by applying impersonation request and response objects.
It can take advantage of JAVA 8 Lambdas.	It can connect to any server via an HTTP connection.

QUESTION: DO YOU THINK SPRING 5 IS COMPATIBLE WITH OLDER VERSIONS OF JAVA?

A: No, Spring 5 is not compatible with older versions of JAVA. IT REQUIRES AT LEAST JAVA 8 TO BE COMPATIBLE.

What are the common Spring interview questions: Can Spring Boot allow Spring MVC or Spring WebFlux in the same application?

A: Yes, Spring Boot can allow either Spring MVC or Spring WebFlux in the same application, but only one application at a time. This is because MVC is a blocking paradigm and WebFlux is a non-blocking paradigm and therefore cannot be used together.

Q: Can Spring MVC run on Netty?

A: No, Spring MVC does not run on Netty.

Q: Can Spring 5 be modularly integrated with JDK9?

A: Yes, Spring 5 can be modularly integrated with JDK9. This can be formulated as follows.

Step 1: Create a new class:

package com.hello;
public class HelloWorld {
    public String sayHello(){
        return "HelloWorld";
    }
}

Step 2: Create a new module:

module com.hello {
    export com.hello;
}

Step 3: Create a new Java project:

module com.hello.client {
    requires com.hello;
}

Step 4: Test the new module:

public class HelloWorldClient {
    public static void main(String[] args){
        HelloWorld helloWorld = new HelloWorld();
        log.info(helloWorld.sayHello());
    }
}

Spring Common Interview Questions & Answers Collection Conclusion

So, that completes the list of the most important questions to ask in a Spring interview. These questions will definitely help you prepare for your Spring interview.

Looking for more Spring Interview Questions? This is a great udemy course: Spring Interview Questions Preparation Course.

A collection of popular Spring common interview questions and answers

Question: Please list the various features of the Spring Framework and the advantages of using them.

What are the common Spring interview questions: How many modules does Spring Framework have?

Question: What are the components of a Spring application?

Question: What is your understanding of Spring IoC Container? Explain their types.

Spring Common Interview Questions and Answers: Please explain the dependency injection in Spring. How many ways can I use the same method?

Question: Can you tell the difference between an ApplicationContext and a BeanFactory in Spring?

Question: How is configuration metadata provided to the Spring container?

Question: What is your understanding of Spring Beans? How many bean scopes does Spring Framework support?

Question: Can you explain the bean lifecycle in the Spring Bean Factory Container?

What are the Common Spring Interview Questions: What Are the Benefits of IoC (Inversion of Control)?

Q: What is the bean lifecycle in Spring Bean Factory Container?

Question: Explain the inner beans in Spring.

Question: What is annotation-based container configuration? Also, explain how to open annotation links in the Spring Framework.

Q: Please explain the various annotations that Spring supports.

Q: What does Spring DAO support mean?

Question: What classes are included in the JDBC API?

Question: How will you use the Spring Framework to access Hibernate?

A collection of common Spring interview questions and answers: List the types of transaction management supported by Spring.

Q: Please explain the AOP technique.

Question: What is Spring’s suggestion? Explain its various types.

Question: Can you compare the concerns and cross-cutting concerns in Spring AOP?

Question: What is your understanding of the Spring MVC framework?

Question: Please explain the DispatcherServlet.

Q: What is Spring?

Question: Is there any difference between a Bean Factory and an Application Context?

What are the Common Spring Interview Questions: What is the difference between Constructor Injection and Setter Injection?

Question: Is Autowriting defined in Spring?

Question: What are the different types of bean scopes in the Spring Framework?

Question: What is the entry point in Spring?

Question: What is JoinPoint?

Q: What is the difference between Spring AOP and AspectJ AOP?

Question: What is a proxy in the Spring Framework?

Question: When is the target object the same as the proxy object?

Question: What is weaving in the Spring framework?

Question: What is Spring Security?

Question: What is Spring Boot?

Question: What is reactive programming?

Question: What are the benefits of reactive programming?

Question: What are the important features of the Reactive system?

Question: What is Spring Webflux?

Spring Common Interview Questions and Answers Collection: Define Mono and Flux Types?

Question: What is the basic difference between Mono and Flux in Spring?

Q: What do Mono and Flux have in common?

Q: What is the difference between a web client and a Webtestclient?

QUESTION: DO YOU THINK SPRING 5 IS COMPATIBLE WITH OLDER VERSIONS OF JAVA?

What are the common Spring interview questions: Can Spring Boot allow Spring MVC or Spring WebFlux in the same application?

Q: Can Spring MVC run on Netty?

Q: Can Spring 5 be modularly integrated with JDK9?

Spring Common Interview Questions & Answers Collection Conclusion

Thao Nguyen