10+ Java Spring Boot Developer Interview Questions and Answers

Spring is a framework that provides a comprehensive programming and configuration model for Java applications. Spring Boot is a framework that simplifies the setup and configuration of Spring applications.

• Spring is a larger framework that provides various modules for different functionalities like dependency injection, MVC, security, etc.

• Spring Boot is an opinionated framework that auto-configures the Spring application with sensible defaults, reducing the need for manual con...read more

Explanation of Java features, Stream API, microservices, HTTP vs HTTPS, and SQL joins.

• Lambda expressions allow for concise syntax to implement functional interfaces.

• Stream API provides a way to process collections of objects in a functional style.

• Microservices architecture breaks down applications into smaller, independent services.

• HTTP is unencrypted protocol, HTTPS is encrypted using SSL/TLS for secure communication.

• Inner join combines rows from two tables based on a relate...read more

Answers to common Java Spring Boot Developer interview questions.

• Java8 features include lambda expressions, functional interfaces, streams, and default methods.

• String is immutable in Java to ensure thread safety and prevent unintended modifications.

• Checked exceptions are checked at compile time, while unchecked exceptions are not. Example: IOException vs NullPointerException.

• throw is used to explicitly throw an exception, while throws is used to declare that a method may thro...read more

Functional interfaces provide clarity and enforce single abstract method constraint.

• Functional interfaces provide clarity to developers by explicitly indicating that the interface is intended to be used as a functional interface.

• Using @FunctionalInterface annotation helps enforce the single abstract method constraint, preventing accidental addition of more abstract methods.

• It also allows the compiler to perform additional checks to ensure that the interface meets the requirem...read more

The question covers topics like method overriding, method overloading, exceptions, Java 8 features, and string manipulation.

• Method overriding is when a subclass provides a specific implementation of a method that is already provided by its superclass.

• Method overloading is when multiple methods have the same name but different parameters.

• Exception handling is used to handle errors that occur during the execution of a program.

• Java 8 introduced features like lambda expressions, ...read more

Logging in Spring Boot is a feature that allows developers to track and record events and errors that occur during application runtime.

• Spring Boot uses the popular logging framework, Logback, for its logging capabilities.

• Developers can configure logging levels and output formats in the application.properties or application.yml file.

• Logging can be used to track application performance, debug errors, and monitor user activity.

• Spring Boot also provides a convenient way to view a...read more

Comparable is an interface in Java used for comparing objects and sorting collections.

• Comparable interface is used to define a natural ordering of objects.

• To implement Comparable, a class must implement the compareTo() method.

• Example: Implementing Comparable interface in a class to compare instances based on a specific attribute.

Memory leak is a situation where a program uses memory inefficiently, causing memory to be allocated but not released.

• Memory leak occurs when a program allocates memory but does not release it after it is no longer needed.

• Identifying memory leaks can be done using tools like profilers to analyze memory usage over time.

• Common signs of memory leaks include increasing memory usage over time, frequent garbage collection, and application crashes due to out-of-memory errors.

Spring Actuator is a tool that provides endpoints to monitor and manage Spring Boot applications.

• Actuator provides health, metrics, info, and other endpoints

• It can be used to monitor and manage the application's health and performance

• Actuator endpoints can be customized and secured using Spring Security

• Examples of endpoints include /health, /metrics, /info, /env, and /shutdown

String is immutable, String Buffer is mutable.

• String is immutable, meaning its value cannot be changed once it is created.

• String Buffer is mutable, meaning its value can be changed after it is created.

• String is faster and more memory efficient for simple string operations.

• String Buffer is slower but more efficient for operations that require frequent modifications.

HTTP status 204 means no content, while 404 means not found.

• HTTP status 204 indicates a successful request, but with no content to return.

• HTTP status 404 indicates that the requested resource could not be found on the server.

• HTTP status 204 is often used for successful DELETE requests where no content needs to be returned.

• HTTP status 404 is commonly seen when a user tries to access a non-existent URL.

Spring Security is a powerful and highly customizable authentication and access-control framework.

• Provides authentication and authorization support for web applications

• Offers a wide range of security features such as password hashing, CSRF protection, and session management

• Can be easily integrated with other Spring frameworks like Spring MVC and Spring Boot

• Supports multiple authentication mechanisms such as form-based, basic, and OAuth2

• Allows for custom security configuration...read more

Dependency injection is a design pattern where the dependencies of a class are provided externally rather than being created within the class itself.

• Dependency injection helps in achieving loose coupling between classes.

• It allows for easier testing and maintenance of code.

• There are three types of dependency injection: constructor injection, setter injection, and interface injection.

• Example: In Spring Boot, dependencies are injected using annotations like @Autowired.

Spring is a framework for building Java applications, while Spring Boot is a tool for easily creating stand-alone, production-grade Spring-based applications.

• Spring is a framework that provides comprehensive infrastructure support for developing Java applications.

• Spring Boot is a tool that simplifies the process of creating and deploying Spring-based applications.

• Spring Boot includes embedded servers, which makes it easy to run applications as standalone JAR files.

• Spring Boot...read more