03 — Environment Setup

Part of: docs/00-INDEX.md

Previous: 02 Learning Path · Next: 02-learn/01 Getting Started

Goal: By the end of this page you can run your first Java program from this project — on your machine, in an IDE or terminal — without hunting for install guides elsewhere.

0. What you are setting up

Project link: https://github.com/srinivasraoravinuthala/JavaMastery

1. Install JDK 21 (Eclipse Temurin)

We recommend Eclipse Temurin (from Adoptium) — free, open source, widely used in tutorials.

Download: https://adoptium.net/temurin/releases/?version=21

Pick JDK 21, your operating system, and x64 (most PCs). Download the .msi (Windows), .pkg (macOS), or .tar.gz / package manager (Linux).

Windows

1. Run the Temurin .msi installer.
2. Keep “Set JAVA_HOME variable” and “Add to PATH” checked (default).
3. Finish the installer.

macOS

1. Run the .pkg installer and follow the prompts.
2. Temurin is usually installed under /Library/Java/JavaVirtualMachines/.

Or with Homebrew:

1brew install temurin@21

Linux (Debian/Ubuntu example)

1sudo apt update2sudo apt install temurin-21-jdk

For other distros, use the .tar.gz from Adoptium or your package manager.

2. Verify Java in the terminal

Open Terminal (macOS/Linux) or Command Prompt / PowerShell (Windows).

1java -version2javac -version

You should see version 21 (or higher — 25 also works). Example:

1openjdk version "21.0.x" ...

Optional — set JAVA_HOME (if IDEs pick the wrong Java):

Add %JAVA_HOME%\bin (Windows) or $JAVA_HOME/bin (macOS/Linux) to PATH.

3. Get the JavaMastery project

Choose one method.

Option A — Git clone (recommended if you use Git)

1git clone https://github.com/srinivasraoravinuthala/JavaMastery.git2cd JavaMastery

Option B — Download ZIP (no Git required)

1. Open https://github.com/srinivasraoravinuthala/JavaMastery
2. Click green Code → Download ZIP
3. Extract the ZIP to a folder you will remember (e.g. Documents/JavaMastery)
4. Open a terminal in that folder — all run commands below assume you are in the project root (you should see folders like pkg0intro, pkg1core, docs)

4. Pick an IDE (choose one)

Both are free. You only need one.

5a. IntelliJ IDEA — open and run

1. Install IntelliJ IDEA Community Edition.
2. File → Open → select your JavaMastery folder → Trust Project.
3. In the Project tree, open pkg0intro/intro1AboutJava.java.
4. Click the green Run arrow next to main, or right-click the file → Run 'intro1AboutJava.main()'.
5. You should see output in the Run panel at the bottom.

Terminal fallback (same folder):

1java pkg0intro/intro1AboutJava.java

If IntelliJ says “No JDK”: File → Project Structure → Project → SDK → add Temurin 21.

5b. Eclipse — import and run

1. Install Eclipse IDE for Java Developers.
2. File → Open Projects from File System… → Directory → select your JavaMastery folder → Finish.
   • If prompted for Maven: you can import as a general Java project; Maven is not required for pkg0 / pkg1 single-file runs.
3. In Package Explorer, open pkg0intro → intro1AboutJava.java.
4. Right-click the file → Run As → Java Application.
5. Output appears in the Console view.

Terminal fallback:

1cd path/to/JavaMastery2java pkg0intro/intro1AboutJava.java

If Eclipse uses the wrong JRE: Window → Preferences → Java → Installed JREs → add Temurin 21.

6. Run from the terminal (project root)

All examples in this course assume you run commands from the JavaMastery root (where pkg0intro lives).

1cd JavaMastery          # skip if already there2java pkg0intro/intro1AboutJava.java3java pkg1core/core1HelloWorld.java

No separate javac step — Java 11+ compiles and runs single files in one command.

7. Install Maven (when you need it)

You do not need Maven for chapters 01–35. Single-file java pkg…/….java is enough.

Install Maven when you reach multi-module build examples (build/) or chapter 36 — Performance & Build.

Verify after install:

1mvn -version

8. How this website fits in

1. Read tutorials here (Orientation → Learn chapters in order).
2. Run the matching .java files locally (steps above) or use Examples → View source → Run online on this site.
3. Learning order:
   • 01 Tutorial & History
   • 02-learn/01 Getting Started
   • pkg0intro → pkg1core (see Learning Path)

9. Ready checklist

Before chapter 02 — Variables & Types, confirm:

• java -version shows 21+
• JavaMastery project is on your machine (clone or ZIP)
• You ran java pkg0intro/intro1AboutJava.java successfully (IDE or terminal)
• You ran java pkg1core/core1HelloWorld.java successfully
• You know where the project root folder is on disk

Troubleshooting

Next → 02-learn/01 Getting Started