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Java Installation Guide

OpenJDK installation and configuration for development

Quick Install

Ubuntu/Debian

# Update package list
sudo apt-get update

# Install OpenJDK 17 (LTS)
sudo apt-get install openjdk-17-jdk

# Verify installation
java -version
javac -version

Other Versions

# Java 11 (LTS)
sudo apt-get install openjdk-11-jdk

# Java 21 (LTS)
sudo apt-get install openjdk-21-jdk

# List available versions
apt-cache search openjdk | grep -E "^openjdk-[0-9]+-jdk"

Version Management

Switch Between Versions

# List installed Java versions
sudo update-alternatives --config java

# Select by entering the number
# Example output:
#   0    /usr/lib/jvm/java-17-openjdk-amd64/bin/java   1711  auto mode
#   1    /usr/lib/jvm/java-11-openjdk-amd64/bin/java   1111  manual mode
# * 2    /usr/lib/jvm/java-17-openjdk-amd64/bin/java   1711  manual mode

# Also switch javac
sudo update-alternatives --config javac

Environment Configuration

Set JAVA_HOME

# Find Java installation path
which java
# /usr/bin/java

# Find actual path (follows symlinks)
readlink -f $(which java)
# /usr/lib/jvm/java-17-openjdk-amd64/bin/java

# JAVA_HOME should be the directory above 'bin'
# /usr/lib/jvm/java-17-openjdk-amd64

Configure System-Wide

Edit /etc/environment:

sudo nano /etc/environment

Add line:

JAVA_HOME="/usr/lib/jvm/java-17-openjdk-amd64"

Apply changes:

source /etc/environment

# Verify
echo $JAVA_HOME

Configure for Current User

Add to ~/.bashrc or ~/.zshrc:

export JAVA_HOME="/usr/lib/jvm/java-17-openjdk-amd64"
export PATH="$JAVA_HOME/bin:$PATH"

Apply:

source ~/.bashrc

Arch Linux

# Install OpenJDK 17
sudo pacman -S jdk17-openjdk

# Switch versions
sudo archlinux-java set java-17-openjdk

# List installed
archlinux-java status

CentOS/RHEL

# Install OpenJDK 17
sudo dnf install java-17-openjdk-devel

# Set default
sudo alternatives --config java

Verification

# Check Java version
java -version

# Check compiler version
javac -version

# Check JAVA_HOME
echo $JAVA_HOME

# Test compilation
echo 'public class Test { public static void main(String[] args) { System.out.println("Hello!"); } }' > Test.java
javac Test.java
java Test
rm Test.java Test.class

Common Paths

Distribution JAVA_HOME Path
Ubuntu/Debian /usr/lib/jvm/java-17-openjdk-amd64
Arch Linux /usr/lib/jvm/java-17-openjdk
CentOS/RHEL /usr/lib/jvm/java-17-openjdk