What is Spring Boot in Spring Boot - Practice Questions & Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the main purpose of Spring Boot?

Spring Boot is designed to simplify the setup and development of new Spring applications. What is its main purpose?

A To provide a way to create standalone, production-grade Spring applications with minimal configuration

B To replace the Spring Framework entirely with a new programming model

C To provide a graphical user interface for managing Spring applications

D To act as a database management system for Spring projects

💡 Hint

Think about how Spring Boot helps developers start projects quickly without much setup.

Spring Boot helps developers create Spring applications quickly by providing defaults and auto-configuration, so you don't have to write a lot of setup code.

❓ component_behavior

intermediate

What happens when you run a Spring Boot application?

When you run a Spring Boot application, what does it do automatically?

A It requires manual setup of the web server before running

B It only compiles the code but does not start any server

C It starts an embedded web server and configures the application context automatically

D It runs the application without loading any Spring components

💡 Hint

Think about how Spring Boot applications are often run as simple Java programs.

Spring Boot automatically starts an embedded server like Tomcat and sets up the application context, so the app is ready to serve requests immediately.

📝 Syntax

advanced

Which annotation is essential to mark a Spring Boot application main class?

In Spring Boot, which annotation should you put on the main class to enable auto-configuration and component scanning?

A @SpringBootApplication

B @EnableAutoConfig

C @SpringBootMain

D @BootApplication

💡 Hint

This annotation combines several others and is the standard entry point marker.

@SpringBootApplication is a convenience annotation that includes @Configuration, @EnableAutoConfiguration, and @ComponentScan.

🔧 Debug

advanced

Why does this Spring Boot app fail to start?

Given this main class code, why does the Spring Boot application fail to start? public class MyApp { public static void main(String[] args) { SpringApplication.run(MyApp.class, args); } }

Spring Boot

public class MyApp {
  public static void main(String[] args) {
    SpringApplication.run(MyApp.class, args);
  }
}

A The main method should be named start instead of main

B The main method should return void instead of static void

C SpringApplication.run requires an instance, not a class

D The class is missing the @SpringBootApplication annotation

💡 Hint

Check if the class is properly marked for Spring Boot to recognize it.

Without @SpringBootApplication, Spring Boot does not know how to configure and start the app.

❓ lifecycle

expert

What is the order of Spring Boot application startup phases?

Arrange these Spring Boot startup phases in the correct order: 1. Application context refresh 2. Auto-configuration 3. Running the main method 4. CommandLineRunner execution

A 3,1,2,4

B 3,2,1,4

C 2,3,1,4

D 3,2,4,1

💡 Hint

Think about what happens first when you run the app and when beans are ready.

First, the main method runs, then Spring Boot performs auto-configuration, then refreshes the application context, and finally runs CommandLineRunner beans.