Maven & Gradle

# Generate a new project with the standard directory layout.
mvn archetype:generate \
  -DgroupId=com.mycompany \
  -DartifactId=my-app \
  -DarchetypeArtifactId=maven-archetype-quickstart \
  -DinteractiveMode=false

cd my-app

# The layout Maven creates AND expects (convention over configuration):
#   src/main/java/        your application source code
#   src/main/resources/   config files (application.properties)
#   src/test/java/        your test code
#   target/               build output (compiled classes + the JAR)
#   pom.xml               the Project Object Model — deps + build config

# Run the build. 'package' runs every phase BEFORE it, in order:
#   validate -> compile -> test -> package
mvn package

[INFO] --- compiler:3.13.0:compile (default-compile) ---
[INFO] Compiling 1 source file to /my-app/target/classes
[INFO] --- surefire:3.2.5:test (default-test) ---
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO] --- jar:3.4.1:jar (default-jar) ---
[INFO] Building jar: /my-app/target/my-app-1.0.0.jar
[INFO] BUILD SUCCESS
[INFO] Total time:  4.218 s

<project xmlns="http://maven.apache.org/POM/4.0.0">
  <modelVersion>4.0.0</modelVersion>

  <!-- GAV coordinates: the three values that uniquely name your artifact. -->
  <groupId>com.mycompany</groupId>      <!-- who: reverse-domain namespace -->
  <artifactId>my-app</artifactId>       <!-- what: the project name -->
  <version>1.0.0</version>              <!-- which release -->

  <properties>
    <maven.compiler.release>21</maven.compiler.release>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <!-- compile scope (the default): on the classpath everywhere. -->
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.17.0</version>         <!-- always PIN an exact version -->
    </dependency>

    <!-- test scope: only on the test classpath, not shipped in the JAR. -->
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter</artifactId>
      <version>5.10.2</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <!-- Plugins add steps to the lifecycle. Shade builds a "fat JAR". -->
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>3.6.0</version>
      </plugin>
    </plugins>
  </build>
</project>

<project xmlns="http://maven.apache.org/POM/4.0.0">
  <modelVersion>4.0.0</modelVersion>

  <!-- 🎯 YOUR TURN — fill in the blanks marked with ___ -->

  <!-- 1) Give this artifact its GAV coordinates. -->
  <groupId>com.example</groupId>
  <artifactId>___</artifactId>          <!-- 👉 name it "todo-app" -->
  <version>___</version>                <!-- 👉 use "1.0.0" -->

  <dependencies>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter</artifactId>
      <version>5.10.2</version>
      <scope>___</scope>                <!-- 👉 tests only: use "test" -->
    </dependency>
  </dependencies>
</project>

<!-- ✅ Expected: 'mvn validate' prints BUILD SUCCESS with -->
<!--    artifactId = todo-app, version = 1.0.0, JUnit on the TEST classpath. -->

// build.gradle (Groovy DSL) — code, not XML. Far less ceremony.

plugins {
    id 'java'                       // adds compile, test, jar tasks
    id 'application'                // adds the 'run' task
}

group = 'com.mycompany'
version = '1.0.0'

repositories {
    mavenCentral()                  // where dependencies are downloaded from
}

dependencies {
    // implementation = compile scope. ONE line vs 7 of XML.
    implementation 'com.fasterxml.jackson.core:jackson-databind:2.17.0'

    // testImplementation = test scope (only on the test classpath).
    testImplementation 'org.junit.jupiter:junit-jupiter:5.10.2'
}

application {
    mainClass = 'com.mycompany.App' // entry point for './gradlew run'
}

tasks.named('test') {
    useJUnitPlatform()              // run tests with the JUnit 5 engine
}

# Always use the wrapper (./gradlew) committed in the repo, NOT a global
# 'gradle' install — the wrapper pins the exact Gradle version for everyone.

./gradlew build          # compile + test + package  (= mvn package)
./gradlew test           # run the tests             (= mvn test)
./gradlew run            # run the application        (= mvn exec:java)
./gradlew clean          # delete build output        (= mvn clean)
./gradlew dependencies   # print the resolved graph   (= mvn dependency:tree)

> Task :compileJava
> Task :test
BUILD SUCCESSFUL in 1s
7 actionable tasks: 4 executed, 3 up-to-date

# ./gradlew dependencies shows TRANSITIVE deps you never listed:
compileClasspath
\--- com.fasterxml.jackson.core:jackson-databind:2.17.0
     +--- com.fasterxml.jackson.core:jackson-annotations:2.17.0
     \--- com.fasterxml.jackson.core:jackson-core:2.17.0

// build.gradle
// 🎯 YOUR TURN — fill in the blanks marked with ___

plugins {
    id 'java'
}

repositories {
    ___()        // 👉 the standard public repo: mavenCentral
}

dependencies {
    // A normal compile-time library:
    ___ 'org.apache.commons:commons-lang3:3.14.0'   // 👉 use: implementation

    // A test-only library:
    ___ 'org.junit.jupiter:junit-jupiter:5.10.2'    // 👉 use: testImplementation
}

// ✅ Expected: './gradlew build' downloads both jars from Maven Central and
//    prints BUILD SUCCESSFUL. commons-lang3 is on the main classpath;
//    junit-jupiter is on the test classpath only.

// 🎯 MINI-CHALLENGE: add a JSON library to a Gradle build
//
// Starting from a build.gradle that already has the 'java' plugin and
// mavenCentral():
//   1. Add Google's Gson as a COMPILE dependency.
//        coordinates -> com.google.code.gson:gson:2.11.0
//   2. Add JUnit 5 as a TEST-ONLY dependency.
//        coordinates -> org.junit.jupiter:junit-jupiter:5.10.2
//   3. Run './gradlew dependencies' to confirm Gson resolved.
//
// ✅ Expected: BUILD SUCCESSFUL, and the dependency report lists
//    com.google.code.gson:gson:2.11.0 on the compileClasspath.

// your build.gradle dependencies { } block here