Maven Java Project

You could create the folders and the pom.xml for a Maven project by hand, but nobody does that. Maven can generate a ready-made project from a template with one command. In this lesson we generate a simple standalone Java project on Windows and look at what Maven created. (If you are working on the Linux VM, the next lesson does the same thing there.)

The command

mvn archetype:generate -DgroupId=com.telusko -DartifactId=telusko-app -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.5 -DinteractiveMode=false

It is long, but every part has a simple job.

Running it

Create an empty folder for your practice projects, for example D:\Maven Projects, open it in File Explorer, type cmd in the address bar and press Enter. That opens a Command Prompt in that folder. Check Maven, then paste the command:

mvn -v
mvn archetype:generate -DgroupId=com.telusko -DartifactId=telusko-app -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.5 -DinteractiveMode=false

The first time you run this, Maven downloads the Archetype plugin and its own dependencies, plus a catalog of templates. You will see many Downloading from central lines. This can take a minute. The next time it finishes in a few seconds, because everything is cached on your machine. It ends with:

[INFO] BUILD SUCCESS

mvn archetype:generate ^
  -DgroupId=com.telusko ^
  -DartifactId=telusko-app ^
  -DarchetypeArtifactId=maven-archetype-quickstart ^
  -DarchetypeVersion=1.5 ^
  -DinteractiveMode=false

mvn archetype:generate "-DgroupId=com.telusko" "-DartifactId=telusko-app" "-DarchetypeArtifactId=maven-archetype-quickstart" "-DarchetypeVersion=1.5" "-DinteractiveMode=false"

mvn archetype:generate \
  -DgroupId=com.telusko \
  -DartifactId=telusko-app \
  -DarchetypeArtifactId=maven-archetype-quickstart \
  -DarchetypeVersion=1.5 \
  -DinteractiveMode=false

What Maven created

A new folder named after the artifactId appears: telusko-app. Inside it there are two important things: a pom.xml file and a src folder.

telusko-app/
├── .mvn/                      <- small Maven config folder (archetype 1.5 only)
├── pom.xml
└── src/
    ├── main/
    │   └── java/
    │       └── com/
    │           └── telusko/
    │               └── App.java
    └── test/
        └── java/
            └── com/
                └── telusko/
                    └── AppTest.java

There is no src/main/resources folder yet. You can create it yourself whenever you need configuration files, and Maven will pick it up automatically because that path is part of its standard layout.

Open App.java in any editor and you will see the classic starter:

package com.telusko;

/**
 * Hello world!
 */
public class App {
    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}

Nobody told Maven to create these folders. The archetype did it, and the same structure appears whether you use the terminal, IntelliJ IDEA or Eclipse. That predictability is the whole point.

Common problems

Try It Yourself

1. Generate telusko-app with the command above and open the folder in File Explorer.
2. Generate a second project with your own groupId (for example com.yourname) and artifactId (for example hello-maven). Check how the package folders change.
3. Run the command once with -DinteractiveMode=true (or without it) and answer the prompts yourself, so you see what the batch mode was skipping.
4. Open the generated pom.xml and find the groupId, artifactId and version you passed (or got as defaults).

Official references

• Apache Maven: Maven in 5 Minutes
• Apache Maven: Quickstart Archetype
• Apache Maven: Introduction to the Standard Directory Layout

Written By: Shramik Masti