Install JDK (17 / 21 / 23)

The Java Development Kit (JDK) is required to develop and run Spring Boot applications.

Without JDK, you cannot compile Java code, run Spring Boot projects, or use tools like Maven and Gradle.

Spring Boot works best with LTS (Long-Term Support) Java versions.

Which JDK Version Should You Choose?

JDK Version	Type	Recommendation
JDK 17	LTS	Most recommended for Spring Boot
JDK 21	LTS	Latest stable & future-ready
JDK 23	Non-LTS	For learning & testing only

? Best choice:

Beginners & production apps → JDK 17
New modern projects → JDK 21

⚠ Avoid using non-LTS versions in production.

Step 1: Download JDK

You can download JDK from trusted providers:

Oracle JDK
OpenJDK
*Eclipse Temurin (Adoptium) Recommended
Amazon Corretto

? Why Eclipse Temurin?

Free & open-source
Production-ready
Widely used in Spring Boot projects

Choose:

OS: Windows / macOS / Linux
Architecture: x64 (most common)
Version: 17 or 21

Step 2: Install JDK

Windows Installation

Download .msi or .exe file
Double-click and install
Use default options
Finish installation

Default path:

C:\\Program Files\\Java\\jdk-17

macOS Installation

Using Installer

Download .pkg file
Open and follow steps
Installation completes automatically

Default path:

/Library/Java/JavaVirtualMachines/

Linux Installation (Ubuntu Example)

For Java 17:

sudo apt update
sudo apt install openjdk-17-jdk

For Java 21:

sudo apt install openjdk-21-jdk

Step 3: Verify JDK Installation

Run these commands in terminal / command prompt:

java -version
javac -version

Example output:

java version "17.0.10"

If both commands work → JDK is installed correctly.

Step 4: Set JAVA_HOME Environment Variable

Why JAVA_HOME is Important?

Required by Maven & Gradle
Required by IDEs (IntelliJ, Eclipse)
Used internally by Spring Boot

Set JAVA_HOME (Windows)

Open Environment Variables
Add new System Variable:

JAVA_HOME = C:\\Program Files\\Java\\jdk-17

Edit Path → Add:

%JAVA_HOME%\\bin

Set JAVA_HOME (macOS / Linux)

export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk-17.jdk/Contents/Home
export PATH=$JAVA_HOME/bin:$PATH

Step 5: Verify JAVA_HOME

echo %JAVA_HOME%     # Windows
echo $JAVA_HOME      # macOS / Linux

Spring Boot & Java Compatibility

Spring Boot Version	Java Requirement
Spring Boot 2.x	Java 8 / 11
Spring Boot 3.x	Java 17+ (mandatory)

? Spring Boot 3 will NOT work with Java 8 or 11.

Common Mistakes to Avoid

Installing JRE instead of JDK
Not setting JAVA_HOME
Using Java 8 with Spring Boot 3
Multiple Java versions without proper PATH

Best Practices

Always use LTS versions (17 or 21)
Verify installation before starting project
Match Java version with Spring Boot version
Keep JAVA_HOME correctly configured

Conclusion

Installing the correct JDK is the foundation of Spring Boot development.

For modern Java applications in 2025:

Use JDK 17 or JDK 21
Set JAVA_HOME properly
Verify installation using terminal

Once JDK is installed, your system is ready for Spring Boot, Maven, Gradle, REST APIs, Microservices, and Enterprise applications