Using Java 21 with VS Code: A Lightweight Workflow

Java 21 brings modern features that simplify development and improve performance. Whether you’re a student, hobbyist, or a developer tired of heavy IDEs like Eclipse or IntelliJ, Visual Studio Code (VS Code) offers a fast, lightweight, and highly productive setup for Java development.

In this guide, you’ll learn how to set up Java 21 with VS Code, write and run your first Java app, and use advanced features like virtual threads, all with minimal configuration.

🚀 Why Use VS Code for Java?

While Java has traditionally been used with heavyweight IDEs, VS Code is:

💨 Fast and lightweight — consumes fewer system resources
🔌 Highly extensible — thousands of extensions available
🎯 Focused — only install what you need
🧪 Great for experimentation — ideal for trying Java 21 features

🛠️ Step 1: Install Java 21

You need Java 21 installed on your system. Java 21 is a Long-Term Support (LTS) release, making it ideal for new projects.

👉 Download Options:

🔍 To verify installation:

java -version

Expected output:

java 21.0.x ...

Also check:

javac -version

🧩 Step 2: Install VS Code and Java Extensions

Download VS Code:
https://code.visualstudio.com
Install Java Extension Pack:
- Open VS Code
- Go to Extensions (Ctrl + Shift + X)
- Search for Java Extension Pack
- Click Install

📦 This includes:

Language support for Java™
Debugger for Java
Maven & Gradle support
Java Test Runner
IntelliSense and formatting

📁 Step 3: Create a Java Project

You can start small with a single .java file or set up a Maven/Gradle project.

📄 Option A: Simple Java file

Open a terminal:

mkdir HelloJava21

cd HelloJava21

code .

Inside VS Code, create a file Hello.java:

public class Hello {

public static void main(String[] args) {

System.out.println("Hello from Java 21!");

}

🔨 Option B: Use Maven (recommended for larger projects)

Open Command Palette (Ctrl + Shift + P)
Run: Java: Create Java Project
Choose Maven
Fill in details like Group ID and Artifact ID
VS Code sets up everything for you

▶️ Step 4: Run Your Java Code

For single files:

Click the Run button that appears above main() in the editor
OR use the terminal:

javac Hello.java

java Hello

If you’re using Maven:

mvn compile

mvn exec:java

🧠 Step 5: Explore Java 21 Features

Now you’re ready to use powerful features in Java 21!

✅ Record Patterns

record Person(String name, int age) {}

static void greet(Object obj) {

if (obj instanceof Person(String name, int age)) {

System.out.println("Hi " + name + ", age " + age);

}

✅ Virtual Threads (Project Loom)

Runnable task = () -> System.out.println("Running on " + Thread.currentThread());

Thread.startVirtualThread(task);

✅ Sequenced Collections

List<String> names = new ArrayList<>();

names.add("Alice");

names.add("Bob");

for (String name : names.reversed()) {

System.out.println(name);

}

You’ll get full IntelliSense, compile-time checking, and tooltips right in VS Code.

🐞 Debugging in VS Code

Debugging in VS Code is straightforward:

Add a breakpoint (click to the left of the line number)
Click the Run and Debug icon on the sidebar
Select Java
Use controls to step through the code, watch variables, and evaluate expressions

🧼 Formatting & Auto Compile

You can format code automatically:

File > Preferences > Settings > Java > Format
Add this to .vscode/settings.json:

{

"editor.formatOnSave": true,

"java.format.settings.profile": "GoogleStyle"

}

You can also enable auto-build so your code compiles as you save.

🧰 Integrating Build Tools

VS Code supports:

Maven (via pom.xml)
Gradle (via build.gradle)

Features include:

Lifecycle commands (clean, compile, test)
Dependency management
Integrated terminal

You’ll see a Maven or Gradle side panel for easy navigation.

🏁 Final Thoughts

VS Code + Java 21 gives you the best of both worlds:

Lightweight and fast tooling
Powerful new language features
Simpler setup than traditional IDEs

Whether you’re building REST APIs, microservices, or learning the language, this setup helps you move fast and stay productive.