How to Create a Maven Project: Archetype, Directory Layout and IntelliJ IDEA - Quiz

Creating a Maven project means getting a directory with a pom.xml file (coordinates groupId, artifactId, version) and the standard folder structure src/main/java, src/test/java and so on. The ways to do it:

• Command line - mvn archetype:generate from a template (an archetype). Requires installed Maven and a JDK; works everywhere, including on a server and in scripts, but the template may contain outdated settings, so check pom.xml.
• IntelliJ IDEA - the New Project wizard: the Java generator with Build system = Maven, or the Maven Archetype generator. Maven is bundled with the IDE, and the project is imported right away.
• Manually - write pom.xml and create the directories. Full control, nothing extra; this is how existing code is moved to Maven.

An archetype is not required: it is just a quick way to get a skeleton. What makes a directory a Maven project is pom.xml and the standard folder layout. The result is the same in every case - a project that builds with mvn package. Spring Boot projects are usually created with start.spring.io (Spring Initializr), which also produces a regular Maven project.

A Maven archetype is a project template published in a repository as a regular artifact: a draft pom.xml, directories and sample classes. Official archetypes (group org.apache.maven.archetypes): maven-archetype-quickstart (jar, an App class and an AppTest test - the default choice), maven-archetype-webapp (war, src/main/webapp), maven-archetype-simple, maven-archetype-archetype (a skeleton for your own archetype).

mvn archetype:generate runs the generate goal of maven-archetype-plugin and creates the project in a subdirectory named after the artifactId. Modes: interactive (a list of archetypes and questions in the console) and batch - -DinteractiveMode=false, all parameters passed with -D (archetypeGroupId, archetypeArtifactId, archetypeVersion, groupId, artifactId, version, package). In batch mode groupId and artifactId are required, version defaults to 1.0-SNAPSHOT, and package equals groupId. Always set the archetype version explicitly. In PowerShell wrap every -D argument in quotes.

After generating, check pom.xml: the Java version (a single maven.compiler.release property instead of the source/target pair - quickstart up to and including 1.4 sets 1.7), the JUnit version (old templates use JUnit 4 or 3.8.1, version 1.5 uses JUnit 5) and the encoding project.build.sourceEncoding = UTF-8.

• groupId - the organization or project group as a reversed domain name you own (or io.github.your-login); stick to lowercase Latin letters, digits and dots so that it is also a valid Java package name. Good: com.examclouds, org.example.shop; bad: MyCompany, com.my-company.
• artifactId - the project name in lowercase, words separated by hyphens, no spaces and no version: hello-maven, online-shop, but not Hello Maven or shop-1.0.
• version - a version number; the -SNAPSHOT suffix means a version in development (1.0-SNAPSHOT), no suffix means a released version (1.0.0).

By default the archetype derives the Java package name from groupId (classes end up in com/examclouds/). If groupId contains a hyphen or a segment that starts with a digit, the generated package will not compile - set a valid -Dpackage explicitly. The artifactId and version form the name of the built file: hello-maven-1.0-SNAPSHOT.jar.

Maven knows the standard paths by default, so you do not declare them in pom.xml - you only need to put files in the right place:

• src/main/java - source code in folders that mirror packages; compiled into target/classes and included in the jar/war.
• src/main/resources - configuration and data (.properties, .xml, .yml, templates, SQL); copied to target/classes, i.e. the classpath root and the jar.
• src/test/java - tests in the same packages as the code under test (so they can access package-private members); compiled into target/test-classes, not included in the jar.
• src/test/resources - files needed only by tests; not included in the jar.
• src/main/webapp - only for packaging = war (WEB-INF/web.xml, JSP, static files).
• target - the build output, nothing is kept there by hand; deleted by mvn clean and added to .gitignore.

Maven does not search the whole project for files: a resource in src/main/java does not reach the jar, a .java file in src/main/resources is never compiled, and a src/java folder is not seen at all (No sources to compile). Override the paths in pom.xml only for an old project that cannot be reorganized.

New project: File → New → Project, the Java generator with Build system = Maven (if you leave IntelliJ, the project has no pom.xml) or the Maven Archetype generator; enter Name, Location, JDK and GroupId/ArtifactId under Advanced Settings. The IDE creates pom.xml and the standard directories and imports the project immediately; there is no need to install Maven separately - it is bundled.

The Maven tool window shows Lifecycle (phases run with a double-click), Plugins and Dependencies. The IDE does not re-read pom.xml on every keystroke: after editing it, click Load Maven Changes (or Reload All Maven Projects in the Maven window), otherwise a new dependency stays red in the code.

Importing an existing project: File → Open → pom.xml → Open as Project; if a pom.xml in a subfolder is not recognized, right-click it → Add as Maven Project.

Settings (Build, Execution, Deployment → Build Tools → Maven): Maven home path - Bundled or your own installation, User settings file and Local repository, Runner - the JDK that runs Maven. The bundled Maven is not available in the Terminal tab, and the IDE and the terminal may run Maven on different JDKs - if the project builds in the IDE but not in the terminal, compare the Runner JDK with the mvn -version output.