Project structure walkthrough in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the src/main/java directory in a Spring Boot project?

It holds the main Java source code files where your application logic, controllers, services, and repositories live.

beginner

What kind of files do you find in src/main/resources?

This folder contains configuration files like application.properties or application.yml, static files, templates, and other resources your app needs.

beginner

What is the role of the pom.xml or build.gradle file in a Spring Boot project?

It manages project dependencies, build settings, and plugins. It tells the build tool how to compile and package your app.

beginner

Where do you put your test code in a Spring Boot project?

Test code goes inside src/test/java. This keeps tests separate from the main application code.

intermediate

Why is it important to follow the standard Spring Boot project structure?

It helps tools and developers understand your project easily, supports automatic configuration, and makes your app easier to maintain.

Which folder contains your main application Java files in Spring Boot?

A src/test/java

B src/main/java

C src/main/resources

D target/classes

The main Java source files are placed in src/main/java.

Where do you place configuration files like application.properties?

A src/test/resources

B src/main/java

C src/main/resources

D src/test/java

Configuration files go into src/main/resources.

What is the purpose of the pom.xml file?

A To manage dependencies and build settings

B To store test cases

C To write Java code

D To hold static web files

pom.xml manages dependencies and build instructions.

Where should you put your unit tests?

A src/main/java

B src/main/resources

C target/test-classes

D src/test/java

Unit tests belong in src/test/java.

Why follow the standard Spring Boot project structure?

A To help tools and developers understand the project easily

B To confuse developers

C To make the project harder to maintain

D To avoid using build tools

Standard structure helps tools and developers work efficiently.

Describe the main folders in a Spring Boot project and what each is used for.

Think about where your code, config, and tests live.

Explain why organizing your Spring Boot project with the standard structure is helpful.

Consider benefits for both developers and tools.

Practice

1. In a typical Spring Boot project, where should you place your main application Java files?

easy

A. src/resources/java

B. src/main/resources

C. src/test/java

D. src/main/java

Solution

1. Step 1: Understand Spring Boot folder roles

   The src/main/java folder is for main Java source code including the application entry point.

2. Step 2: Identify correct folder for main Java files

   Main application files should not be in resources or test folders, so src/main/java is correct.

3. Final Answer:

   src/main/java -> Option D

4. Quick Check:

   Main Java code = src/main/java [OK]

Hint: Main Java code always goes under src/main/java [OK]

Common Mistakes:

• Confusing resources folder with Java source folder
• Placing main code in test folder
• Using incorrect folder names like src/resources/java

2. Which file is commonly used to manage dependencies and build steps in a Spring Boot Maven project?

easy

A. pom.xml

B. application.properties

C. build.gradle

D. settings.xml

Solution

1. Step 1: Identify build tool for Maven projects

   Maven uses pom.xml to manage dependencies and build configuration.

2. Step 2: Differentiate from Gradle and config files

   build.gradle is for Gradle, application.properties is for app config, and settings.xml is not for dependencies.

3. Final Answer:

   pom.xml -> Option A

4. Quick Check:

   Maven build file = pom.xml [OK]

Hint: Maven uses pom.xml; Gradle uses build.gradle [OK]

Common Mistakes:

• Confusing application.properties with build files
• Mixing Gradle and Maven build files
• Thinking settings.xml manages dependencies

3. Given this Spring Boot project structure snippet, where will the test Java files be located?

src/
  main/
    java/
    resources/
  test/
    java/
    resources/

medium

A. src/main/resources

B. src/test/java

C. src/main/java

D. src/test/resources

Solution

1. Step 1: Understand test folder purpose

   The src/test/java folder is for Java test source files.

2. Step 2: Identify test Java files location

   Test Java files go under src/test/java, not in main or resources folders.

3. Final Answer:

   src/test/java -> Option B

4. Quick Check:

   Test Java code = src/test/java [OK]

Hint: Test Java files go in src/test/java folder [OK]

Common Mistakes:

• Putting test Java files in src/main/java
• Confusing test resources with test Java code
• Using src/main/resources for tests

4. You accidentally placed your application.properties file inside src/main/java. What problem will this cause?

medium

A. The application will fail to start due to missing config

B. The build will fail with a syntax error

C. The properties file will be ignored and default config used

D. The application.properties will be loaded correctly anyway

Solution

1. Step 1: Know where Spring Boot loads config files

   Spring Boot loads application.properties from src/main/resources or classpath root.

2. Step 2: Effect of wrong file location

   If placed in src/main/java, it won't be found and ignored, so defaults apply.

3. Final Answer:

   The properties file will be ignored and default config used -> Option C

4. Quick Check:

   Config files must be in resources, else ignored [OK]

Hint: Config files must be in resources folder to load [OK]

Common Mistakes:

• Assuming app fails to start immediately
• Thinking build fails due to config file location
• Believing misplaced properties still load

5. You want to add a new configuration file for your Spring Boot app that should be packaged inside the jar and accessible at runtime. Where should you place this file?

hard

A. src/main/resources/config

B. src/main/java/config

C. src/test/resources/config

D. src/main/resources/static

Solution

1. Step 1: Understand resource packaging in Spring Boot

   Files in src/main/resources are packaged inside the jar and available at runtime.

2. Step 2: Choose correct folder for config files

   Config files should be under src/main/resources/config to be included and organized.

3. Final Answer:

   src/main/resources/config -> Option A

4. Quick Check:

   Runtime config files go in src/main/resources [OK]

Hint: Put runtime config files in src/main/resources folder [OK]

Common Mistakes:

• Placing config files in src/main/java which is for code
• Using test resources folder which is not packaged
• Putting config in static folder meant for web assets