20+ Springboot Developer Interview Questions and Answers

The question covers various topics related to SpringBoot development.

• LinkedList vs ArrayList: LinkedList is better for frequent insertions/deletions, ArrayList is better for frequent access.

• Tomcat vs other application servers: Tomcat is a lightweight server, while others like JBoss are more feature-rich.

• AJAX JSON: AJAX is used to make asynchronous requests to the server, while JSON is a lightweight data interchange format.

• Method overriding Polymorphism: Method overriding is w...read more

Method overloading is having multiple methods in the same class with the same name but different parameters. Method overriding is having a method in a subclass with the same name and parameters as a method in its superclass.

• Method overloading allows a class to have multiple methods with the same name but different parameters.

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

• Method overloading is ...read more

Create a Spring Boot application to generate an XML file from two input values.

• Create a Spring Boot project using Spring Initializr

• Create a REST controller to accept two input values

• Use JAXB to generate XML from the input values

• Return the generated XML file as response

Yes, @RestController combines @Controller and @ResponseBody annotations in Springboot for simplified REST API creation.

• Combines @Controller and @ResponseBody annotations

• Eliminates the need to annotate every method with @ResponseBody

• Simplifies REST API creation by directly returning data

RestController is specialized version of controller used for RESTful web services in Spring framework.

• RestController is used to create RESTful web services that return JSON or XML data, while Controller is used to create web pages that return HTML data.

• RestController annotation is a combination of @Controller and @ResponseBody annotations.

• RestController is typically used for building RESTful APIs, while Controller is used for handling web requests in a traditional MVC applica...read more

Annotation used to define RESTful web services in Spring Boot

• Used to create RESTful web services in Spring Boot

• Combines @Controller and @ResponseBody annotations

• Eliminates the need to annotate every request handling method with @ResponseBody

Program to insert comma after every character in a string.

• Iterate through each character in the string

• Append the character and a comma to a new string

• Handle the last character to avoid adding an extra comma

Bean factory is a container for managing beans in Spring framework.

• Bean factory is responsible for creating, managing, and configuring beans in a Spring application.

• It uses inversion of control (IoC) to manage the beans.

• Beans are defined in a configuration file (XML or Java) and the bean factory instantiates them.

• Example: ApplicationContext is a type of bean factory in Spring framework.

The @Bean annotation is used to define a method that returns an object to be registered as a bean in the Spring application context. The @Component annotation is used to indicate that a class is a Spring component.

• The @Bean annotation is used on methods within a @Configuration class to define Spring beans.

• The @Component annotation is used on classes to indicate that they are Spring components.

• The @Bean annotation allows for more flexibility in defining bean creation logic com...read more

Singleton is a design pattern that restricts the instantiation of a class to only one object.

• Ensures a class has only one instance and provides a global point of access to it.

• Commonly used in scenarios where a single instance of a class is needed, such as database connections or thread pools.

• Implemented by creating a static method to return the same instance of the class every time it is called.

Java 8 introduced parallel programming concepts like streams, parallel streams, and CompletableFuture.

• Java 8 introduced streams which allow for functional-style operations on collections.

• Parallel streams allow for parallel processing of stream elements, improving performance on multi-core processors.

• CompletableFuture class enables asynchronous programming by representing a future result of an asynchronous computation.

Spring filters are components in Spring framework that intercept incoming HTTP requests and outgoing HTTP responses.

• Filters are used to perform tasks like logging, authentication, authorization, etc.

• They are configured in the web.xml file or using annotations like @WebFilter.

• Example: javax.servlet.Filter interface is implemented to create custom filters.

Spring Boot is a framework that simplifies the development of Java applications by providing pre-configured setups.

• Spring Boot eliminates the need for manual configuration by providing defaults for most settings.

• It allows developers to create stand-alone, production-grade Spring-based applications with minimal effort.

• Spring Boot includes embedded servers like Tomcat, Jetty, or Undertow, making it easy to deploy applications.

• It promotes convention over configuration, reducing ...read more

Static keyword is used in Java to create class-level variables and methods.

• Static variables are shared among all instances of a class

• Static methods can be called without creating an instance of the class

• Static keyword can also be used to create static blocks for initialization

Abstract classes can have both abstract and non-abstract methods, while interfaces can only have abstract methods.

• Abstract classes can have constructors, fields, and methods, while interfaces cannot.

• A class can implement multiple interfaces but can only extend one abstract class.

• Abstract classes are used to define a common behavior for subclasses, while interfaces are used to define a contract for classes to implement.

• Example: Abstract class - Animal with abstract method 'eat...read more

SOLID is a set of five design principles to make software designs more understandable, flexible, and maintainable.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable with objects of its subclasses without affecting the program's correctness.

• I - Interface Segregation...read more

JPA is a specification while Hibernate is an implementation of JPA.

• JPA is a Java specification for managing relational data in applications.

• Hibernate is an ORM framework that implements the JPA specification.

• Hibernate provides additional features beyond JPA, such as caching and lazy loading.

• JPA is vendor-neutral, allowing developers to switch between different JPA implementations.

• Hibernate is a popular choice for JPA implementation due to its extensive features and community ...read more

Flat map is used to flatten nested collections, while map is used to transform elements in a collection.

• Flat map is used when you have a collection of collections and you want to flatten it into a single collection.

• Map is used to transform each element in a collection using a given function.

• Example: Using flatMap to flatten a list of lists - list.stream().flatMap(List::stream).collect(Collectors.toList())

• Example: Using map to convert a list of strings to uppercase - list.stre...read more