Why IntelliJ IDEA and Eclipse Differ: Project Structure, Maven, and Best Practices

Introduction

After many years of Java development, you may wonder why files such as xxx.iml and the .idea folder should not be committed to Git, how to migrate a project from Eclipse to IDEA without structural issues, and what a Maven project looks like in IDEA’s Project Structure.

Why are xxx.iml and the .idea folder important yet prohibited from Git commits?

If a project was created with Eclipse, can it be continued in IDEA without problems?

How does a Maven project imported into IDEA work, and what is its Project Structure?

If you have these questions, this article is for you.

Outline

Version Specification

IntelliJ IDEA: 2020.3.2

SpringToolSuite: 4.9.0.RELEASE

Main Content

We will explore the differences between IDEA and Eclipse project structures.

IntelliJ IDEA Project

Eclipse Project

Eclipse uses a workspace concept where all projects are managed together; a single window can open multiple projects simultaneously.

Creating a Project

Example of creating a Java project named hello in Eclipse:

File -> New -> Java Project...

The wizard is considered overly complex, showing many unnecessary options.

After finishing, the project appears as shown:

Project Settings

Select the project, right‑click, and choose Properties to configure it. Eclipse lacks a Module concept; hierarchy is expressed only by folder paths.

Eclipse Has No Module Concept

To create a sub‑project hello-client under hello, you must create a new project and place it in the desired folder.

The Project Explorer view shows the folder hierarchy, while the Package Explorer view displays the logical structure without modules.

Eclipse’s .classpath file defines the Java build path, and the .project file describes the project name, type, and build commands.

.classpath File

Stores the compile‑time classpath, referenced by $CLASSPATH.

.project File

Provides a complete project description, including name, comment, build command ( org.eclipse.jdt.core.javabuilder), and nature ( org.eclipse.jdt.core.javanature).

.settings Directory

Contains various configuration files, mostly .prefs or XML files, such as org.eclipse.core.resources.prefs (file encoding) and org.eclipse.jdt.core.prefs (Java compiler settings).

Structural Differences: IDEA vs Eclipse

The two IDEs manage projects differently: logical structure, metadata files, and file formats are not compatible. Maven solves this by providing a standard project layout that both IDEs can import.

Standardization with Maven

Using Maven, all developers can work with the same project structure regardless of IDE. When committing to Git, IDE‑specific files should be excluded via .gitignore:

# eclipse ignore
.settings/
.project
.classpath

# idea ignore
.idea/
*.ipr
*.iml
*.iws

Creating/Importing Maven Projects

Both IDEA and Eclipse fully support Maven. In IDEA, select Maven when creating a new project, configure the archetype, and finish.

After creating a parent module, add sub‑modules (e.g., hello-client and hello-service) and declare dependencies in pom.xml. IDEA automatically reflects these dependencies in its Project Structure.

Importing an existing Maven project in IDEA is as simple as opening the pom.xml or the project folder.

Maven Dominates Java Project Management

Maven provides a Project Object Model (POM), a standard directory layout, a lifecycle, and a powerful dependency management system, making it the de‑facto standard for medium and large Java projects.

Although Gradle is gaining traction, especially in Android development, Maven remains the stable backbone of the Java ecosystem.

Conclusion

This article clarified the differences between IDEA and Eclipse project management, explained why IDE‑specific files should not be committed to Git, and showed how Maven standardizes builds so developers no longer need to worry about IDE‑specific details.