Transitive Dependencies¶

Dependency of your dependency.

Example:

Project -> Spring Web -> Jackson

You added Spring Web, but Jackson also gets downloaded automatically.

groupId, artifactId, version¶

groupId¶

Organization / company name.

<groupId>org.springframework.boot</groupId>

artifactId¶

Project/library name.

<artifactId>spring-boot-starter-web</artifactId>

version¶

Specific release/version.

<version>3.5.0</version>

Archetype¶

Template project generator.

Example:

mvn archetype:generate

Creates starter structure automatically.

Dependency Scopes¶

Default Scope = compile¶

Available:

• compile

• test

• runtime

Included in final build.

<scope>compile</scope>

Usually omitted because it's default.

provided Scope¶

Needed during compile, but server/container provides it at runtime.

Example:

<scope>provided</scope>

Typical:

Servlet API in Tomcat

Not packaged into final JAR/WAR.

runtime Scope¶

Not needed for compilation.\ Needed only while running app.

Example:

<scope>runtime</scope>

Typical:

Database driver

test Scope¶

Only available during testing.

Example:

<scope>test</scope>

Typical:

JUnit
Mockito

Not included in production build.

Maven Properties¶

Reusable variables/constants inside pom.xml.

Example:

<properties>
    <java.version>21</java.version>
</properties>

Usage:

<version>${java.version}</version>

Avoids repeating hardcoded values.

<exclusions> in Dependencies¶

Prevents unwanted transitive dependencies.

Example:

<dependency>
    <groupId>org.example</groupId>
    <artifactId>demo</artifactId>

    <exclusions>
        <exclusion>
            <groupId>com.bad.library</groupId>
            <artifactId>bad-lib</artifactId>
        </exclusion>
    </exclusions>
</dependency>

Used when:

• dependency conflicts

• duplicate versions

• security issues

• unnecessary large libraries

Project Object Model (POM)¶

pom.xml = Maven project blueprint/configuration.

Controls:

• dependencies

• plugins

• build lifecycle

• packaging

• project metadata

POM Location¶

Located at:

project-root/pom.xml

Maven commands search current directory for pom.xml.

Parent / Super POM¶

Maven supports inheritance.

Super POM¶

Default Maven configuration inherited automatically.

Parent POM¶

Custom shared config across projects.

Example:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
</parent>

<repository>¶

Defines where dependencies are downloaded from.

Default:

Maven Central Repository

Official:\ Maven Central Repository

Structure of POM File¶

1. Project Metadata¶

Project identity/details.

Example:

<name>demo</name>
<version>1.0</version>
<packaging>jar</packaging>

2. Dependencies¶

Libraries project needs.

Example:

<dependencies>
</dependencies>

3. Plugins¶

Extra build tasks/tools.

Example:

• test reports

• code analysis

• executable JAR generation

Maven Lifecycle¶

Validate¶

Checks project structure/config.

Compile¶

Converts source code → .class files.

Output:

target/classes

Test¶

Runs unit tests.

Package¶

Creates distributable artifact.

Example:

JAR / WAR

Verify¶

Runs quality/integrity checks.

Example:

• static analysis

• integration checks

Install¶

Stores package in local Maven repository.

Location:

~/.m2/repository

Deploy¶

Uploads package to remote repository.

Used in CI/CD pipelines.

<build> Tag¶

Customize build process.

Example:

<build>
    <plugins>
    </plugins>
</build>

Used to:

• add plugins

• customize phases

• generate reports

• package apps

Core Structure of pom.xml¶

1. <project>¶

Root element of POM.

2. Identity¶

<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>1.0</version>

Uniquely identifies project.

3. <parent>¶

Inherits shared/default configuration.

4. <properties>¶

Centralized reusable config values.

Example:

<java.version>21</java.version>

5. <dependencies>¶

External libraries required by project.

6. <build> + <plugins>¶

Defines how project is built/executed.

7. Metadata¶

Optional publishing information.

Example:

<name>
<description>
<licenses>

Bottom Line¶

Runtime Dependency Example¶

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-devtools</artifactId>
    <scope>runtime</scope>
</dependency>

Meaning:

• needed only while app runs

• not needed for compilation

Maven Wrapper (mvnw)¶

Runs Maven project without globally installing Maven.

Linux/Mac:

./mvnw clean install

Windows:

mvnw.cmd clean install

Why mvnw Matters¶

1. No Maven Installation Needed¶

Project ships its own Maven wrapper.

2. Version Consistency¶

Entire team uses same Maven version.

Avoids:

"Works on my machine"

problems.

3. Auto Download¶

If required Maven version missing:

• wrapper downloads correct version automatically

• runs build immediately

Important Real-World Insight¶

Most Maven confusion comes from:

• not understanding dependency scopes

• not understanding transitive dependencies

• randomly copying dependencies from StackOverflow

Strong developers:

• inspect dependency trees

• control versions deliberately

• minimize unnecessary dependencies

Useful command:

mvn dependency:tree

This exposes:

• transitive dependencies

• version conflicts

• duplicate libraries