Exercise-4

5. Practical Exercise: Build and Run a Java Application with Maven, Migrate the Same Application to Gradle

Part 1: Build and Run a Java Application Using Maven

Step 1: Create a Maven Project

Open a terminal and run:

mvn archetype:generate -DgroupId=com.example -DartifactId=myapp -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

Then, navigate into the project folder:

cd myapp

OUTPUT:


Step 2: Verify Project Structure

After running the command, your project will have this structure:

myapp
│── src
│   ├── main
│   │   └── java
│   │       └── com.example
│   │           └── App.java
│   ├── test
│   │   └── java
│   │       └── com.example
│   │           └── AppTest.java
│── pom.xml

OUTPUT:

Step 3: Update App.java (Main Application)

Modify src/main/java/com/example/App.java:

package com.example;

public class App {
    public static void main(String[] args) {
        System.out.println("Hello from Maven!");
    }
}

OUTPUT:


Step 4: Configure pom.xml for JUnit and Plugins

Modify pom.xml:

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
         http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>myapp</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.2.0</version>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>com.example.App</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

OUTPUT:

Step 5: Build and Run the Application with Maven

Compile and Build the JAR

mvn clean package

OUTPUT:

Run the Application

java -jar target/myapp-1.0-SNAPSHOT.jar

Expected Output:

Hello from Maven!

OUTPUT:

Part 2: Migrate the Same Application to Gradle

Step 1: Create a New Gradle Project

Navigate outside your Maven project folder and run:

mkdir myapp-gradle
cd myapp-gradle
gradle init

Step 2: Copy Java Files from Maven to Gradle

Manually copy the src folder from myapp (Maven project) to myapp-gradle.

(Note: replace myapp-gradle src folder with myapp src folder)

Step 3: Modify build.gradle.kts (Kotlin DSL)

Edit build.gradle.kts:

plugins {
    java
    application
}

repositories {
    mavenCentral()
}

dependencies {
    implementation("org.springframework.boot:spring-boot-starter-web:2.7.0")
    testImplementation("junit:junit:4.13.2")
}

application {
    mainClass.set("com.example.App")
}

OUTPUT:

Step 4: Build and Run the Application with Gradle

Compile and Build the JAR

gradle clean build

OUTPUT:

Run the Application

gradle run

Expected Output:

Hello from Maven!

OUTPUT:

---

Summary

Step	Maven Command	Gradle Command
Create Project	mvn archetype:generate	gradle init
Compile Code	mvn compile	gradle build
Run Tests	mvn test	gradle test
Build JAR	mvn package	gradle jar
Run Application	java -jar target/myapp-1.0-SNAPSHOT.jar	gradle run