Installing the JDK

To start developing in Java you need to install the JDK — the Java Development Kit. It includes the javac compiler, the JVM, the standard library, and various utilities. Several JDK distributions are available — they all implement the same OpenJDK standard but differ in licensing and support.

ℹ️For learning purposes Eclipse Temurin (Adoptium) is recommended — it is free, has no licensing restrictions, and is available at adoptium.net.

Installing the JDK

Select your operating system — the instructions differ by platform.

Via winget (recommended — built into Windows 10/11)

bash

winget install EclipseAdoptium.Temurin.25.JDK

# Verify
java -version
javac -version

If winget is unavailable — download the .msi from adoptium.net and run it. The installer sets PATH automatically.

bash

# After manual install — verify in a new terminal
java -version
javac -version

Configuring JAVA_HOME

Many build tools and IDEs use the JAVA_HOME environment variable to locate the JDK. Without it Maven, Gradle and others may fail to start.

Add to ~/.bashrc or ~/.zshrc

bash

export JAVA_HOME=/usr/lib/jvm/temurin-25
export PATH=$JAVA_HOME/bin:$PATH

# Apply immediately
source ~/.bashrc

# Verify
echo $JAVA_HOME
java -version

Verifying the Installation

After installation open a new terminal and run through these verification steps:

bash

java -version
# openjdk version "25.0.x" ...
# OpenJDK Runtime Environment Temurin-25...

javac -version
# javac 25.0.x

which java   # Linux/macOS
where java   # Windows

⚠️If the java command is not found after installation — close and reopen your terminal. Changes to PATH only take effect for new sessions.

Managing Multiple JDK Versions

Real-world projects often require switching between Java versions. Dedicated version managers exist for this purpose.

bash

# SDKMAN! — usage examples
sdk install java 25-tem      # install Temurin 25
sdk install java 21-tem      # install Temurin 21
sdk use java 21-tem          # switch for current session
sdk default java 25-tem      # set global default
sdk current java             # show active version

✅SDKMAN! is the best choice for developers on Linux/macOS. It manages not only Java but also Maven, Gradle, Kotlin, Scala, and other JVM tools.