Multi-module project structure in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the parent project packaging type.

Spring Boot

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.example</groupId>
  <artifactId>parent-project</artifactId>
  <version>1.0.0</version>
  <packaging>[1]</packaging>
</project>

Drag options to blanks, or click blank then click option'

Awar

Bpom

Cear

Djar

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'jar' packaging for the parent project.

Confusing packaging types like 'war' or 'ear'.

The parent project in a multi-module Spring Boot project uses pom packaging to manage modules.

2fill in blank

medium

Complete the code to include a module named 'service' in the parent POM.

Spring Boot

<modules>
  <module>[1]</module>
</modules>

Drag options to blanks, or click blank then click option'

Arepository

Bweb

Cservice

Dcommon

Attempts:

3 left

💡 Hint

Common Mistakes

Using module names that do not exist in the project.

Confusing module names with artifact IDs.

The service module is included as a child module in the parent POM.

3fill in blank

hard

Fix the error in the child module POM to inherit from the parent project.

Spring Boot

<parent>
  <groupId>com.example</groupId>
  <artifactId>parent-project</artifactId>
  <version>[1]</version>
</parent>

Drag options to blanks, or click blank then click option'

A1.0.0

B1.0

Clatest

Dsnapshot

Attempts:

3 left

💡 Hint

Common Mistakes

Using incomplete or incorrect version strings.

Omitting the version tag.

The child module must specify the exact version of the parent project to inherit correctly.

4fill in blank

hard

Fill both blanks to define the parent and artifact IDs in a child module POM.

Spring Boot

<parent>
  <groupId>[1]</groupId>
  <artifactId>[2]</artifactId>
  <version>1.0.0</version>
</parent>

Drag options to blanks, or click blank then click option'

Acom.example

Bservice

Cparent-project

Dcom.service

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up groupId and artifactId values.

Using module names instead of parent project names.

The child module must reference the parent's groupId and artifactId to inherit configuration.

5fill in blank

hard

Fill all three blanks to define a dependency in a child module POM.

Spring Boot

<dependency>
  <groupId>[1]</groupId>
  <artifactId>[2]</artifactId>
  <version>[3]</version>
</dependency>

Drag options to blanks, or click blank then click option'

Aorg.springframework.boot

Bspring-boot-starter-web

C3.0.5

Dcom.example

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect groupId or artifactId.

Omitting the version or using wrong version format.

This dependency adds Spring Boot web starter with the specified version.

Practice

1. What is the main purpose of a multi-module project in Spring Boot?

easy

A. To create multiple databases for one application

B. To run multiple Spring Boot applications simultaneously

C. To split a large project into smaller, manageable parts

D. To avoid using pom.xml files

Solution

1. Step 1: Understand project organization

   Multi-module projects break a big codebase into smaller modules for easier management.

2. Step 2: Identify the main goal

   This splitting helps teams work on parts independently and share code efficiently.

3. Final Answer:

   To split a large project into smaller, manageable parts -> Option C

4. Quick Check:

   Multi-module = smaller parts [OK]

Hint: Think of dividing work into smaller folders [OK]

Common Mistakes:

• Confusing multi-module with running multiple apps
• Thinking it removes the need for pom.xml
• Assuming it creates multiple databases

2. Which file typically manages all modules in a Spring Boot multi-module project?

easy

A. application.properties

B. module-specific application.yml

C. settings.gradle

D. parent pom.xml

Solution

1. Step 1: Identify the build management file

   In Maven-based Spring Boot projects, the parent pom.xml controls all modules.

2. Step 2: Understand file roles

   Other files like application.properties configure app settings, not modules.

3. Final Answer:

   parent pom.xml -> Option D

4. Quick Check:

   Parent pom manages modules [OK]

Hint: Parent pom.xml controls modules [OK]

Common Mistakes:

• Confusing application.properties with module management
• Thinking settings.gradle is used in Maven projects
• Assuming module-specific files manage all modules

3. Given a multi-module project with modules core and web, where web depends on core, what happens if core is not built before web?

medium

A. The web module build will fail due to missing dependencies

B. The web module will build successfully without core

C. Both modules will build independently without errors

D. The core module will build automatically after web

Solution

1. Step 1: Understand module dependencies

   If web depends on core, it needs core built first to access its code.

2. Step 2: Consequence of build order

   Building web without core causes missing dependency errors and build failure.

3. Final Answer:

   The web module build will fail due to missing dependencies -> Option A

4. Quick Check:

   Dependent module needs dependency built first [OK]

Hint: Build dependencies before dependents [OK]

Common Mistakes:

• Assuming modules build independently
• Thinking build order does not matter
• Believing dependent modules build automatically

4. You have a multi-module Spring Boot project but the web module cannot find classes from the core module. What is the most likely cause?

medium

A. The core module is not listed as a dependency in web's pom.xml

B. The web module has no application.properties

C. The parent pom.xml is missing the modules section

D. The core module is using a different Java version

Solution

1. Step 1: Check module dependencies

   If web cannot find core classes, it likely lacks a dependency declaration on core.

2. Step 2: Verify dependency declaration

   Adding core as a dependency in web's pom.xml fixes class visibility.

3. Final Answer:

   The core module is not listed as a dependency in web's pom.xml -> Option A

4. Quick Check:

   Missing dependency causes class not found [OK]

Hint: Always declare module dependencies in pom.xml [OK]

Common Mistakes:

• Ignoring dependency declarations
• Thinking application.properties affects class visibility
• Assuming Java version mismatch causes missing classes

5. In a multi-module Spring Boot project, you want to share common utility classes across modules without duplicating code. Which approach is best?

hard

A. Copy utility classes into each module's source folder

B. Create a separate common module and add it as a dependency to other modules

C. Put all utility classes in the parent pom.xml

D. Use application.properties to share utility classes

Solution

1. Step 1: Identify code sharing strategy

   To avoid duplication, create a dedicated common module for shared utilities.

2. Step 2: Use module dependencies

   Other modules add common as a dependency to access shared code cleanly.

3. Final Answer:

   Create a separate common module and add it as a dependency to other modules -> Option B

4. Quick Check:

   Shared code in common module [OK]

Hint: Use a common module for shared code [OK]

Common Mistakes:

• Copying code causes duplication and maintenance issues
• Trying to put code in pom.xml (not for code)
• Using properties files to share classes