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Spring Boot has become a must-know framework for Java developers, especially those working on web and microservices applications. Its simplicity and ability to get applications running with minimal setup make it a favorite in the industry. Because of this, employers often include Spring Boot-related questions in interviews to test your hands-on knowledge and problem-solving skills.
Here, we’ve listed the most relevant Spring Boot interview questions and answers to help you succeed. These include basics like project structure and annotations, as well as advanced topics like Spring Boot starters, security, and deployment.
We’ve explained each answer in a simple and easy-to-understand way so you can quickly grasp the ideas. Whether you’re preparing for your first Java developer job or switching roles, this guide will help you feel more prepared and confident. Read on and give your Spring Boot interview prep a strong start!
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order_small=”0″ spacing_left_medium=”” spacing_right_medium=”” spacing_left_small=”” spacing_right_small=”” spacing_left=”” spacing_right=”” margin_top_medium=”” margin_bottom_medium=”” margin_top_small=”” margin_bottom_small=”” margin_top=”” margin_bottom=”” padding_top_medium=”” padding_right_medium=”” padding_bottom_medium=”” padding_left_medium=”” padding_top_small=”” padding_right_small=”” padding_bottom_small=”” padding_left_small=”” padding_top=”20px” padding_right=”20px” padding_bottom=”20px” padding_left=”20px” hover_type=”none” border_sizes_top=”” border_sizes_right=”” border_sizes_bottom=”” border_sizes_left=”” border_color=”” border_style=”solid” border_radius_top_left=”” border_radius_top_right=”” border_radius_bottom_right=”” border_radius_bottom_left=”” box_shadow=”no” box_shadow_vertical=”” box_shadow_horizontal=”” box_shadow_blur=”0″ box_shadow_spread=”0″ box_shadow_color=”” box_shadow_style=”” background_type=”single” gradient_start_color=”” gradient_end_color=”” gradient_start_position=”0″ gradient_end_position=”100″ gradient_type=”linear” radial_direction=”center center” linear_angle=”180″ background_color=”” background_image=”” background_position=”left top” background_repeat=”no-repeat” background_blend_mode=”none” render_logics=”” filter_type=”regular” filter_hue=”0″ filter_saturation=”100″ filter_brightness=”100″ filter_contrast=”100″ filter_invert=”0″ filter_sepia=”0″ filter_opacity=”100″ filter_blur=”0″ filter_hue_hover=”0″ filter_saturation_hover=”100″ filter_brightness_hover=”100″ filter_contrast_hover=”100″ filter_invert_hover=”0″ filter_sepia_hover=”0″ filter_opacity_hover=”100″ filter_blur_hover=”0″ animation_type=”” animation_direction=”left” animation_speed=”0.3″ animation_offset=”” last=”true” border_position=”all” first=”true”][fusion_accordion type=”accordions” boxed_mode=”no” border_size=”1″ border_color=”” background_color=”” hover_color=”” divider_line=”” title_font_size=”” icon_size=”” icon_color=”” icon_boxed_mode=”” icon_box_color=”#4f4f4f” icon_alignment=”right” toggle_hover_accent_color=”#3ed9df” hide_on_mobile=”small-visibility,medium-visibility,large-visibility” class=”interview_list” id=””][fusion_toggle title=”Question 61: What is Spring Initializer?” open=”no” class=”” id=””]
Answer:
Spring Initializer is a web-based tool and a command-line interface that simplifies the process of creating and configuring Spring Boot applications. Spring Boot is a framework that makes it easier to set up and develop Java applications by providing a wide range of default configurations and sensible defaults. Spring Initializer allows developers to quickly generate a new Spring Boot project with the necessary dependencies, configuration files, and directory structure based on their requirements.
[/fusion_toggle][fusion_toggle title=”Question 62: Why Spring Data REST is not recommended in real-world applications?” open=”no” class=”” id=””]
Answer:
Spring Data REST isn’t recommended for real-world applications due to its direct exposure of database entities as REST services. When crafting RESTful services, the primary concerns are the domain model and consumer experience. However, Spring Data REST overlooks these factors and directly reveals entities. Therefore, it’s recommended to utilize Spring Data REST primarily during the project’s initial stages.
[/fusion_toggle][fusion_toggle title=”Question 63: Explain the difference between the SpringApplication.run() and SpringApplication.run(Class, String) methods.” open=”no” class=”” id=””]
Answer:
Both methods are used to start a Spring Boot application. SpringApplication.run(Class, String[]) allows you to pass the primary application class along with command-line arguments, whereas SpringApplication.run() can be used without specifying the primary class if it’s called from within the primary class itself.
[/fusion_toggle][fusion_toggle title=”Question 64: How does Spring Boot simplify the creation of RESTful APIs?” open=”no” class=”” id=””]
Answer:
Spring Boot provides the @RestController annotation, which combines the @Controller and @ResponseBody annotations. This allows you to create RESTful APIs easily by writing methods that return domain objects directly, which are then automatically serialized to JSON or XML. Spring Boot also includes built-in support for content negotiation and exception handling in REST APIs.
[/fusion_toggle][fusion_toggle title=”Question 65: What is Spring Boot Actuator, and what is its significance?” open=”no” class=”” id=””]
Answer:
Spring Boot Actuator is a set of production-ready features that help in monitoring and managing Spring Boot applications. It provides endpoints for gathering application metrics, health checks, application environment details, and more. Actuator endpoints are crucial for monitoring application health and performance in production environments.
[/fusion_toggle][fusion_toggle title=”Question 66: How does Spring Boot support externalized configuration?” open=”no” class=”” id=””]
Answer:
Spring Boot allows you to externalize configuration properties using various property sources such as property files, YAML files, environment variables, and command-line arguments. Properties defined in these sources can be accessed in Spring components using the @Value annotation or through the Environment object.
[/fusion_toggle][fusion_toggle title=”Question 67: What is the purpose of the Spring Boot Starter modules?” open=”no” class=”” id=””]
Answer:
Spring Boot Starter modules are a set of pre-configured dependencies that facilitate the setup of specific functionalities. Each starter module includes a set of common dependencies and configuration to simplify development. For example, the “spring-boot-starter-web” module includes dependencies and configuration for building web applications.
[/fusion_toggle][fusion_toggle title=”Question 68: Explain the concept of ”auto-configuration” in Spring Boot.” open=”no” class=”” id=””]
Answer:
Auto-configuration in Spring Boot refers to the mechanism by which the framework automatically onfigures beans based on the classpath and the presence of specific dependencies. Spring Boot’s auto-configuration feature helps developers avoid writing a significant amount of boilerplate code by providing sensible defaults and configurations for various Spring components.
[/fusion_toggle][fusion_toggle title=”Question 69: What is the use of @Transactional annotation in Spring Boot?” open=”no” class=”” id=””]
Answer:
The @Transactional annotation in Spring Boot is used to indicate that a method or a class should be managed within a transactional context. Transactions are used to ensure the integrity and consistency of data in a database. When a method is annotated with @Transactional, Spring Boot automatically handles the creation, management, and completion of database transactions.
[/fusion_toggle][fusion_toggle title=”Question 70: How can you resolve whitelabel error page in spring boot application?” open=”no” class=”” id=””]
Answer:
We can address this issue using three main approaches:
- Custom Error Controller: In this method, you will need to implement the ErrorController interface provided by the Spring Framework. By overriding the getErrorPath() method, you can define a custom path to handle specific errors that occur. This allows you to have more control over how errors are handled and presented.
- Displaying a Custom Error Page: To implement this approach, you’ll create an html page and place it in the src/main/resources/templates directory. Spring Boot’s BasicErrorController will automatically utilize this file as the default error page. This method provides the flexibility to design and display error messages according to your requirements.
- Disabling the Whitelabel Error Page: The simplest method is to disable the whitelabel error page. You can achieve this by setting the error.whitelabel.enabled property to false in the application.properties file. By doing so, the default generic error page provided by Spring Boot will not be displayed, giving you the option to handle errors in a more customized manner.
[/fusion_toggle][fusion_toggle title=”Question 71: What is bootstrapping in spring boot?” open=”no” class=”” id=””]
Answer:
Bootstrapping refers to the process of initializing and configuring a Spring application with minimal manual configuration. Spring Boot is an extension of the Spring framework that aims to simplify the development of Java applications by providing default settings, sensible defaults, and automatic configuration based on convention over configuration principles.
[/fusion_toggle][fusion_toggle title=”Question 72: Which is the latest version of the Spring Boot?” open=”no” class=”” id=””]
Answer:
The latest version of spring boot is 2.6.0 that offers various dependency upgrades, Java 15 support and much more.
[/fusion_toggle][fusion_toggle title=”Question 73: How to check the environment properties in a Spring boot application?” open=”no” class=”” id=””]
Answer:
In a Spring Boot application, you can check the environment properties using the Environment object provided by the Spring framework. This object gives you access to various properties and configuration settings that your application uses.
Here’s how you can check environment properties in a Spring Boot application:
- Inject Environment Object: In your Spring component (such as a controller, service, or configuration class), you can inject the Environment object using Spring’s dependency injection mechanism.
- Using @Value Annotation: You can also use the @Value annotation to directly inject specific properties into your components
- Accessing Application Properties File: Spring Boot applications typically use a properties file (like properties or application.yml) to store configuration. You can define properties in this file and access them using the methods mentioned above.
[/fusion_toggle][fusion_toggle title=”Question 74: What is an IOC container?” open=”no” class=”” id=””]
Answer:
An IOC (Inversion of Control) container is a software design pattern used in computer programming. The main purpose of an IOC container is to manage the instantiation and lifecycle of objects in a program by “inverting control” from the program itself to the container.
In traditional programming, the application code explicitly creates and manages instances of various classes and their dependencies. With an IOC container, this responsibility is shifted to the container itself. The container keeps track of the various classes and their dependencies, and it provides a way to request instances of these classes whenever needed.
[/fusion_toggle][fusion_toggle title=”Question 75: What are the basic annotations that Spring Boot offers?” open=”no” class=”” id=””]
Answer:
Some of the basic annotations provided by Spring Boot are:
- @SpringBootApplication
- @Controller
- @RestController
- @RequestMapping
- @Autowired
- @Component
- @Repository
- @Configuration
- @EnableAutoConfiguration
[/fusion_toggle][fusion_toggle title=”Question 76: What is the main difference between @RestController and @Controller in Spring Boot?” open=”no” class=”” id=””]
Answer:
In Spring Boot, both @RestController and @Controller are used to create components that handle incoming HTTP requests. However, they serve slightly different purposes:
- @Controller: The @Controllerannotation is used to define a class as a Spring MVC controller. It is typically used for creating controllers that handle the presentation layer of a web application. These controllers are responsible for processing requests, interacting with the model, and returning a view to be rendered on the client side. In a @Controller class, methods that handle different URL mappings return the name of the view to be displayed.
- @RestController: The @RestControllerannotation, on the other hand, is used to define a class as a Spring MVC controller that specializes in handling RESTful APIs. Unlike @Controller, @RestController methods don’t return views. Instead, they directly return data (usually in JSON or XML format) that gets serialized and sent as a response to the client. This annotation is suitable for building APIs where the response is not HTML-based but data-driven.
[/fusion_toggle][fusion_toggle title=”Question 77: How does Spring Boot simplify the development of microservices?” open=”no” class=”” id=””]
Answer:
Spring Boot provides features like embedded web servers, auto-configuration, and production-ready monitoring to simplify the development, deployment, and management of microservices. It also supports building RESTful APIs, which is a common communication pattern between microservices.
[/fusion_toggle][fusion_toggle title=”Question 78: What is the purpose of Spring Cloud in microservices architecture? ” open=”no” class=”” id=””]
Answer:
Spring Cloud is a set of tools and libraries that provides support for building and deploying distributed systems and microservices-based applications. It offers solutions for service discovery, configuration management, load balancing, and more.
[/fusion_toggle][fusion_toggle title=”Question 79: How can you achieve communication between microservices in Spring Boot? ” open=”no” class=”” id=””]
Answer:
Microservices can communicate using various protocols such as HTTP/REST, messaging queues, and service discovery mechanisms (e.g., Netflix Eureka). Spring Cloud provides libraries and tools to simplify these communication patterns.
[/fusion_toggle][fusion_toggle title=”Question 80: What is Eureka in Spring Cloud? ” open=”no” class=”” id=””]
Answer:
Eureka is a service discovery server that allows microservices to register themselves and discover other services. It helps in dynamic scaling, load balancing, and failure recovery in a microservices environment.
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