If you’re considering a career in the Spring Framework and are looking for a suitable QnA set to help you prepare for your interviews, check out this blog post on the top 50 questions with proper justification and examples. It will definitely help you to ace the interviews. But first, let’s take a quick look at the market’s demand for and status of the Spring Framework before moving on to the Spring Interview Questions.
The Spring Framework has thrived in the market ever since its release. The spring community is constantly innovating and has grown into a vast ecosystem. Today, it holds the top position in the framework market. Check out the graph below, which displays the market’s most popular frameworks as of January 2018
If you’re wondering why Spring certification is so popular, the reason is that it offers a complete programming and configuration model for contemporary Java-based enterprise applications. It is not concerned with the deployment platform used. Infrastructure support for applications is a crucial component of the Spring Framework. Given the announcement of additional major releases, it is extremely unlikely that the market will disappear anytime soon.
Let’s look at some of the most frequently asked Spring Interview Questions before continuing.
Top Spring Interview Questions and Answers for Freshers and Experienced | Code Decode
Toptal sourced essential questions that the best Spring developers and engineers can answer. Driven from our community, we encourage experts to submit questions and offer feedback.
What are some of the available implementations of a Spring Bean Factory?
All Spring beans, along with their dependencies, are actually instantiated, configured, and managed by a BeanFactory. Bean factories are represented by the interface org. springframework. beans. factory. BeanFactory and its sub-interfaces including:.
All of which are implemented with:
It’s crucial to remember that implementations can relate to various interfaces. 2 .
Which steps of beans lifecycle can be overridden or controlled?
When the bean is loaded into the container using the @PostConstruct annotation and the init-method attribute in the xml configuration, the init() method is called. Through the destroy-method attribute in the xml configuration and the @PreDestroy annotation, the destroy() method is called when the bean is unloaded from the container. The client code must remove objects and release expensive resources that the prototype beans are holding if a bean is prototype-scoped. Try using a custom BeanPostProcessor, which keeps a reference to beans that need to be cleaned up, to get the Spring container to release resources held by prototype-scoped beans.
A developer can implement different interfaces, such as InitializingBean and DisposableBean, as well as BeanNameAware, BeanFactoryAware, and ApplicationContextAware, to call specific behavior during a bean’s life cycle. 3 .
Which of the bean scopes supported by Spring is used by default, and what do the others mean?
The Spring Framework supports following scopes:
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What is dependency injection (DI) and what kinds of DI are there?
The idea behind dependency injection is that you should describe how your objects should be created rather than creating them yourself and then expect pre-created objects to be passed in instead. A configuration file or an annotation can be used to specify which components are required instead of directly connecting your components together. The Spring container is responsible for the rest.
DI can be either constructor based or setter based. When the container calls a class constructor with a number of arguments, each of which represents a dependency on other classes, constructor-based DI is accomplished. When a bean is instantiated and the container calls the bean’s setter methods, this results in setter-based dependency injection. 5 .
Describe the Spring bean lifecycle.
The lifecycle of a Spring bean consists the following steps:
setBeanName() method of BeanNameAware setBeanFactory() method of BeanFactoryAware setApplicationContext() of ApplicationContextAware BeanPostProcessor afterPropertiesSet() method of InitializingBeanBeanPostProcessor destroy() method of DisposableBean For all scopes except prototype, numbers 11 and 12 are accurate because Spring does not oversee the full lifecycle of a prototype bean; instead, the container creates, configures, and otherwise puts together a prototype object before giving it to the client, erasing all traces of that prototype instance. 6 .
What are some examples of how to use a Spring Application Context?
An ApplicationContext is an interface extending BeanFactory’s functionality. ApplicationContext offers the following capabilities in addition to those of the BeanFactory:
ResourcePatternResolver interfaceApplicationEventPublisher interface)MessageSource interface).It’s read-only while the application is running.
The easiest way to create an ApplicationContent instance is:
Loading resources is done with:
Publishing events is as simple as:
Internationalization support messages can be done by:
What is a “stereotype” in the context of Spring, what are the stereotypes that exist, and how do they differ?
A class-level annotation called a “stereotype” indicates the conceptual, as opposed to implementation-level, roles that various types or methods play in the overall architecture. In Spring, these annotations live in the package org. springframework. stereotype.
Currently, this package has the following annotations:
@Component indicates that an annotated class is a “component”. Such classes are considered as candidates for auto-detection when using annotation-based configuration and classpath scanning.@Controller indicates that an annotated class is a “Controller” (e.g. a web controller).@Repository indicates that an annotated class is a “Repository”, originally defined by Domain-Driven Design (Evans, 2003) as “a mechanism for encapsulating storage, retrieval, and search behavior which emulates a collection of objects”.@Service indicates that an annotated class is a “Service”, originally defined by Domain-Driven Design (Evans, 2003) as “an operation offered as an interface that stands alone in the model, with no encapsulated state.” May also indicate that a class is a Business Service Facade (in the Core J2EE patterns sense) or something similar.A developer can easily distinguish the function of the annotated classes thanks to these various types. Starting with Spring 2. As a specialization of @Component, @Controller, @Repository, and @Service enable implementation classes to be automatically detected through classpath scanning. 8 .
How are properties loaded and injected into a Spring Bean?
Let’s say we have a custom. database connection timeout property called connection is defined in the properties file. timeout. We must define a propertyConfigurer bean in order to load this property into a Spring context:
After that, we can inject properties into other beans using the Spring Expression Language:
The same is available in the configuration that uses annotations, as follows:
What various configuration options are there for a class to be a Spring Bean?
Spring Bean can be configured in a variety of ways, including XML configuration, Java configuration, and annotation configuration.
Any object may be added to a Spring Context and later used as a standard bean.
The @Bean annotation, which is combined with @Configuration classes, can be used to configure a Spring Bean.
Classes may also use the annotations @Component, @Service, @Repository, and @Controller to set them up as Spring Beans. To search for these classes in this situation, the base package location must be given, as follows:
What is Bean wiring? How does autowiring work?
The process of injecting Spring Bean dependencies while initializing is known as bean wiring. Although it’s generally recommended to explicitly wire all dependencies (using XML configuration, for instance), Spring also supports autowiring with the @Autowired annotation. The context:annotation-config element must be included in the Spring configuration file in order to enable this annotation. When autowiring, the bean name must be provided with the @Qualifier annotation to prevent conflicts in bean mapping.
There are different ways to autowire a Spring Bean:
byName – to use this type setter method for dependency injection, the variable name should be the same in both the class where the dependency will be injected and in the Spring configuration file.byType – in order for this to function, there should be only one bean configured for that specific class.byType, but type is applied to constructor arguments.byType.11 .
Which dependency injection method is better: Constructor-based or setter-based?
You can use both Constructor-based and Setter-based Dependency Injection. Utilizing constructor arguments for required dependencies and setters for optional dependencies is the ideal solution.
These are only meant to be a guide because there are other aspects of interviews besides trying technical questions. Not all “A” candidates who are worth hiring will be able to respond to all of them, and responding to all of them does not guarantee an “A” candidate. Hiring is still ultimately a science, an art, and a lot of work.
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In order to resolve this issue, spring boot handles the error message and converts it into a meaningful and comprehensive message that is simple to understand and interpret. In the real-time scenario, let’s say that the majority of exception messages are system generated and have straightforward information.
With Spring Boot Actuator 2. X, all endpoints except health and Info are disabled. To enable them you need to set management. endpoints. web. exposure. include=*.
In addition to benefits, there are a few issues we should consider before implementing the spring boot framework to create a microservice-based architecture.
Service B, as a producer, is bound by a contract that Service A, as a consumer, creates. Even though they are implemented in different code bases and use different JVMs, this contract serves as the invisible glue that holds the services together. Breaking changes can be detected immediately during build time.
Multiple services work together in a typical Microservice architecture to provide a comprehensive functionality. These set of service instances might have their network locations assigned dynamically. Additionally, the services adapt to changes in load. Resolving the services needed for operation in a cloud environment could be challenging for common functionality.
Spring Interview Questions
Here are the Top 50 Spring Interview Questions that the Interviewer is Most Likely to Ask. These questions will undoubtedly help you succeed in the interview if you’re looking to work in this industry. I’ve divided the questions into a few categories for your convenience, including:
You can view the webinar recording of the Spring Interview Questions, in which our instructor shared his knowledge and expertise to help you succeed in any Spring Interview.
Spring Boot Interview Questions
| Spring | Spring Boot |
| A web application framework based on Java | A module of Spring |
| Provides tools and libraries to create customized web applications | Used to create a Spring application project which can just run/ execute |
| Spring is more complex than Spring Boot | Spring Boot is less complex than the Spring framework |
| Takes an unopinionated view | Takes an opinionated view of a platform |
FAQ
What are scenario based Java interview questions?
Tricky Java Interview Questions Explain how the decorator design pattern in I/O classes works. Describe how one can call one constructor to another constructor in a class. Describe the function of the intern() method in the String class.
What are some questions about Spring?
What are the key characteristics of the various Spring Framework versions? General Questions – Spring Interview Questions What is a Spring Framework? . List the advantages of Spring Framework. What are the different features of Spring Framework? . What are the modules in the Spring Framework, how many of them are there?
What is IoC container in Spring interview questions?
It is the responsibility of the Spring IoC container to initialize resources or beans and inject them as dependencies. The Spring framework makes it simple to create unit test cases because our business logic doesn’t directly depend on classes that implement resources.
Can we use spring boot with applications which are not using Spring?
Yes, using the starter dependencies will allow you to replace the embedded Tomcat with any other servers. You can do that by using spring-boot-starter-jetty or another dependency for your needs.
