The preparation for Spring Boot interview questions is one of the essential stages for any future Java developer who wants to build a career in the sphere of backend and web application development. The framework has become so popular and widely adopted that it is now one of the must-know topics for any job interview in the area of Java application development. It is vital for a candidate to know and understand the main differences between the Spring Framework and Spring Boot, and be aware of the key concepts and terms related to the framework. The deeper understanding of how it works under the hood and what benefits it offers to the developers, compared to plain Spring, is also essential for the job interview.
Introduction to Spring Boot Interviews
The Spring Framework is an open-source application framework initially launched as a Java application framework. It has been adopted as the standard framework for Java application development on the Java platform. The Spring Framework consists of several modules, each of which defines a set of features to be implemented in the applications written in Java.
The Spring Boot framework is an open-source, java-based framework used by developers to build applications faster. The framework is specifically popular among developers due to its ability to allow the creation of applications with less coding, with built-in servers, dependency injections, and component scans out-of-the-box. It is one of the most discussed topics during the job interviews for Java application developers, as well as backend and web application developers.
As Spring Boot is a modern framework, it is expected from the candidates to know not only the theoretical aspects of it but also to demonstrate their practical knowledge and skills related to it. The ability to explain why Spring Boot is used for the development of Java applications and which benefits it brings to the developers is crucial to pass the interview.
Spring Framework vs. Spring Boot
The Spring Framework is the basis of most Java applications. It provides developers with a wide range of features required to develop modular applications and web applications in particular. However, it can be complicated to configure the application with all the required components and dependencies, as the necessary configuration code has to be written manually.
The Spring Boot framework was introduced to address the issue of complex configuration, enabling developers to create applications faster and with less coding. It is an opinionated framework that aims to reduce the time spent on configuration and prototyping of applications. A Spring Boot framework comes with an embedded repository server, allowing the developers to build applications from scratch faster. Those facts make it one of the most in-demand frameworks among the developers, as they enable them to work on enterprise-level backend applications.
It is a common question during the job interviews for the Java developer positions to explain the difference between the two frameworks. The main difference between those frameworks, in my opinion, is that by using Spring Boot, the developers can benefit from a number of features which otherwise would require writing a significant amount of additional code. For instance, by using the Spring Boot framework, the developers can utilize version management, auto-configuration, a repository server, component scan, and other useful features that significantly reduce the amount of code written manually.
How the Spring Boot Framework Works
The Spring Boot framework works with annotations and auto-configuration. The auto-configuration mechanism is based on the dependencies that the project needs to fulfill, as it configures the Spring Boot application with default values. Thus, it considerably reduces the amount of code and the time required to set up the application.
The framework uses the @SpringBootApplication annotation to set up the application, which in turn uses component scan to locate components. By convention, the @ComponentScan annotation scans packages that are declared in the components. It makes the development of applications easier, as the component scan locates the right packages and sets up the components. However, it also allows more control to be established over the scanning process.
Project Creation in the Spring Boot Framework
The Spring Initializr web application is designed to generate Spring Boot projects. It is often required for the developers to create a project before starting the development process. It is one of the most common tasks related to the Spring Boot framework during the job interviews. To create a project, a developer is supposed to use the web application and choose the option to create a project. Then, the developer has to enter certain details regarding the project, generate it, and proceed to the next steps. As a result, a project with all the necessary files and configuration will be created.
I think this task is essential for the job interview for a Java developer position, as it is the first step to start building applications with the framework. Understanding the process of how to create a project using the Spring Initializr web application is a sign of a competent candidate.
Starter Dependency
One of the main characteristics of the Spring Boot framework is that it comes with a set of starter dependencies, which are used to build the application from scratch. Each of the dependencies is grouped according to the set of similar features that the project will be utilizing. The dependencies are essential for the development process, as they considerably reduce the amount of code that the developers need to write.
A large number of third-party libraries can be utilized within the Spring Boot framework. It is possible due to the fact that each of the libraries is compatible with the framework, and has an embedded component that allows it to be utilized within the Spring Boot project. Thus, Spring Boot offers the developers a set of dependencies that provide the applications with everything they need to fulfill.
In terms of job interviews, the Spring Boot starter dependencies are a great topic to discuss. I think it is important to know that they are the part of the Spring Boot framework that allows building applications with minimum effort, compared to the plain Spring framework.
Inversion of Control, Dependency Injection, and Beans
Dependency Injection is the main concept of the Spring framework. It is the process when the Spring IoC (Inversion of Control) container injects the required beans into the classes. The beans represent Spring-managed objects, which become independent entities that reduce the level of coupling within the application. They also make the components easier to test, maintain, and modify.
The IoC is the underlying mechanism of the Spring framework, which allows it to be modular. It enables the development of applications with a higher degree of abstraction, separation of concerns, and flexibility. The IoC container is not a single software entity, but rather a set of various features that make the application configurable. They allow the developers to manage the objects within the application, define their behavior, and inject dependencies into them.
I believe it is crucial for the candidate to be familiar with the concepts of IoC and Dependency Injection, as well as to know how they are being used in the Spring Boot framework. Knowing the concepts and being able to explain them is essential for the job interviews for Java developer positions.
Embedded Containers and Servers
The embedded server is another concept that is worth discussing during the job interview. It is required for the Spring Boot applications, as they are designed to launch independently. There are three embedded containers that are supported by the Spring Boot framework: Tomcat, Jetty, and Undertow. The default one is Tomcat, which is used to launch the application in the local environment. To change the port of the Tomcat server, it is required to configure it in the properties file of the application. It is one of the common tasks that might be required during the job interviews.
By default, the port of the Tomcat server in the Spring Boot application is 8080. If a candidate knows how to change it, it demonstrates that they understand how the configuration process works.
The embedded Tomcat server can also be changed, depending on the needs of the project. The change can be beneficial when there is a need to utilize a specific feature that is supported only by another server. In my opinion, this is an important topic for the Spring Boot interview, as it demonstrates the practical knowledge of the candidate in the field.
It should also be noted that Spring Boot is not only for web applications, but rather for applications in general. Thus, the framework can be used for non-web application development, if the relevant dependencies are removed or turned off.
Spring Actuator
One of the most important tools that the Spring Boot framework offers to the developers is the Spring Actuator. It is a feature of the framework that provides the developers with the information about the application. It can be used to see which beans are present in the Spring context, as well as to see request mappings, and other useful information.
I believe that the topic of the Spring Actuator is one of the most important for the job interview, as it demonstrates the level of practical knowledge of the candidate. With this feature, the developers can keep track of the important information about the application, such as the list of beans and request mappings. This information is critical in case of problems with the application.
Profiles in Spring Boot
The Spring Profiles are used to differentiate the configurations of the application and to store them separately, based on the environment. The majority of the applications are launched in the development, QA, and production environments, and the configuration of each of them differs significantly. Thus, it is crucial to store them separately and to have an opportunity to switch between them.
Those differences are commonly related to the database configurations. For instance, the QA and production environments use an enterprise-level database, whereas the development environment uses an embedded one. Also, the credentials to access the database can be different for each of the environments. It is possible to store those configurations separately using the Spring profiles. Thus, the application will be able to switch between them, according to the environment that it is launched in.
Preparing for the Interview
To prepare for the job interview, it is essential to learn and understand the key concepts and terms related to the Spring Boot framework. It is also critical to go over the main features of the framework and to have a clear understanding of how to use them. The practical experience is crucial to demonstrate the required level of competence, which is why it is important to practice creating the project and using it in practice.
Thus, to prepare for the Spring Boot interview, it is essential to study the most important concepts, including the difference between the Spring and Spring Boot, annotations, component scans, dependency injection, beans, IoC, starter dependencies, embedded containers, application configuration, servers, Spring profiles, and Spring Actuator. In addition, it is also vital to gain practical experience, such as creating the project, launching it on the Tomcat server, etc.
I think it is also helpful to practice answering the common questions related to the framework. For instance, it is possible to answer the question of how to replace the default server. The answer to that question is to find the spring-boot-starter-web dependency, replace it with another server, or remove it if the server is not needed. One of the most common questions related to the Spring Boot is whether it can be used for non-web application development. The answer is positive, as the web-related features can be turned off.
For me, the process of preparing for the interview is highly motivating, as it is a great opportunity to demonstrate the expertise in the chosen sphere.
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