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.

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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.

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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

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Step 2: Install JDK

Windows Installation

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

Default path:

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

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macOS Installation

Using Installer

1. Download .pkg file
2. Open and follow steps
3. Installation completes automatically

Default path:

/Library/Java/JavaVirtualMachines/

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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

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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.

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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

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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

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Set JAVA_HOME (macOS / Linux)

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

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Step 5: Verify JAVA_HOME

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

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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.

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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

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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

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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