How to Install Java on Debian

Java on Debian usually means OpenJDK packages in main—free, maintained with the distribution, and integrated with update-java-alternatives. Current LTS lines (21) and newer releases (25 on Trixie) install with apt. Older majors (8, 11, 17) depend on your Debian release; when Debian drops a version, Eclipse Temurin from Adoptium fills the gap.

This guide covers install Java on Debian for Debian 11 (Bullseye), 12 (Bookworm), and 13 (Trixie): default-jdk, versioned openjdk-*-jdk packages, Temurin (summary—full steps in install Temurin on Debian), Oracle manual installs, JAVA_HOME, version switching, and uninstall. I ran the commands on Debian 13 and kept real terminal output below.

Tested on: Debian 13 (trixie); kernel 6.12.94+deb13-amd64; amd64; OpenJDK 21.0.11, OpenJDK 25.0.3, and Temurin 21.0.11+10.

Choose an install method

Most readers should use openjdk-<version>-jdk from Debian when that version exists in their suite. Add Temurin when apt-cache policy openjdk-17-jdk (or your target) shows no Candidate.

What each Debian release ships

Per Debian Wiki — Java and package names in main:

Always confirm on your host:

. /etc/os-release && echo "$PRETTY_NAME"
apt-cache policy default-jdk default-jre | head -12
apt-cache search '^openjdk-[0-9]+-jdk'

On Trixie:

Debian GNU/Linux 13 (trixie)
default-jdk:
  Candidate: 2:1.21-76
openjdk-21-jdk - OpenJDK Development Kit (JDK)
openjdk-21-jdk-headless - OpenJDK Development Kit (JDK) (headless)
openjdk-25-jdk - OpenJDK Development Kit (JDK)
openjdk-25-jdk-headless - OpenJDK Development Kit (JDK) (headless)

Prerequisites

• Debian 11, 12, or 13 on amd64 (arm64 OpenJDK packages exist for many releases).
• sudo for apt installs.
• Enough disk space—each full JDK is roughly 200–400 MB with dependencies.

Check existing Java:

java -version 2>&1 || echo "java: not installed"
javac -version 2>&1 || echo "javac: not installed"
update-java-alternatives --list 2>/dev/null || true

Install OpenJDK with apt (recommended)

Install the suite default

sudo apt update
sudo apt install -y default-jdk
java -version
javac -version

default-jdk is a metapackage—on Trixie it depends on OpenJDK 21, not Java 25.

Install a specific OpenJDK major

When you need an explicit version (for example 25 on Trixie):

sudo apt install -y openjdk-25-jdk
apt-cache policy openjdk-25-jdk | head -8

openjdk-25-jdk:
  Installed: 25.0.3+9-2~deb13u1
  Candidate: 25.0.3+9-2~deb13u1

Install 21 the same way:

sudo apt install -y openjdk-21-jdk

ii  openjdk-21-jdk  21.0.11+10-1~deb13u2  amd64  OpenJDK Development Kit (JDK)

JDK, JRE, and headless variants

Example for a minimal server:

sudo apt install -y openjdk-21-jre-headless

Install Eclipse Temurin (Adoptium)

When Debian main does not ship your Java major—common for Java 21 on Bookworm or Java 8 on newer suites—use Eclipse Temurin:

sudo apt install -y wget gpg
sudo install -d -m 0755 /etc/apt/keyrings
wget -qO - https://packages.adoptium.net/artifactory/api/gpg/key/public \
  | gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/adoptium.gpg > /dev/null
echo "deb [signed-by=/etc/apt/trusted.gpg.d/adoptium.gpg] https://packages.adoptium.net/artifactory/deb \
  $(awk -F= '/^VERSION_CODENAME/{print$2}' /etc/os-release) main" \
  | sudo tee /etc/apt/sources.list.d/adoptium.list
sudo apt update
sudo apt install -y temurin-21-jdk
java -version

openjdk version "21.0.11" 2026-04-21 LTS
OpenJDK Runtime Environment Temurin-21.0.11+10 (build 21.0.11+10-LTS)

Temurin 17 on Trixie (when Debian main has no openjdk-17-jdk):

temurin-17-jdk:
  Candidate: 17.0.19.0.0+10-1

See install Temurin on Debian for tarball installs, update-alternatives, and uninstall.

Install Oracle JDK manually

Oracle JDK is not in Debian apt (apt-cache search oracle-java returns nothing useful on Trixie). Download from Oracle Java downloads or use the legacy java.com Linux x64 installer for the JRE.

Typical workflow:

1. Download the .tar.gz or .deb from Oracle for your architecture.
2. Extract to /opt/jdk-XX or install the .deb with apt on a local package.
3. Register with update-alternatives or set JAVA_HOME in /etc/profile.d/.

Most open-source workloads on Debian should prefer OpenJDK or Temurin (OpenJDK install guide).

Switch between installed JDKs

After multiple JDK packages are installed:

update-java-alternatives --list

java-1.21.0-openjdk-amd64      2111       /usr/lib/jvm/java-1.21.0-openjdk-amd64
java-1.25.0-openjdk-amd64      2511       /usr/lib/jvm/java-1.25.0-openjdk-amd64
temurin-21-jdk-amd64           2111       /usr/lib/jvm/temurin-21-jdk-amd64

Set the active default:

sudo update-java-alternatives --set java-1.25.0-openjdk-amd64
java -version 2>&1 | head -2

openjdk version "25.0.3" 2026-04-21
OpenJDK Runtime Environment (build 25.0.3+9-2-deb13u1-Debian)

Switch to Debian OpenJDK 21:

sudo update-java-alternatives --set java-1.21.0-openjdk-amd64
java -version 2>&1 | head -2

openjdk version "21.0.11" 2026-04-21
OpenJDK Runtime Environment (build 21.0.11+10-1-deb13u2-Debian)

Installing OpenJDK 25 does not automatically change the default when Temurin 21 shares the same priority—explicitly --set the JDK you want.

Set JAVA_HOME

Point JAVA_HOME at the JVM root (parent of bin):

export JAVA_HOME=$(dirname $(dirname $(readlink -f $(which java))))
export PATH="$JAVA_HOME/bin:$PATH"
echo "$JAVA_HOME"
java -version

Examples after selecting each alternative:

Persist system-wide:

echo 'export JAVA_HOME=/usr/lib/jvm/java-21-openjdk-amd64' | sudo tee /etc/profile.d/java.sh
echo 'export PATH="$JAVA_HOME/bin:$PATH"' | sudo tee -a /etc/profile.d/java.sh

Note: update-java-alternatives names like java-1.21.0-openjdk-amd64 differ from directory names like java-21-openjdk-amd64—use readlink or the path from --list.

Verify with a sample program

mkdir -p ~/javatest
cat > ~/javatest/Hello.java <<'EOF'
public class Hello {
  public static void main(String[] args) {
    System.out.println("Hello, Java on Debian");
  }
}
EOF
javac ~/javatest/Hello.java
java -cp ~/javatest Hello

Hello, Java on Debian

If javac: command not found, you installed a JRE only—install openjdk-*-jdk.

Check the manual page:

MANPAGER=cat man java 2>/dev/null | head -6

Update Java

sudo apt update
sudo apt install --only-upgrade 'openjdk-*-jdk' 'temurin-*-jdk'
java -version

List installed JDK packages with list installed packages on Debian:

dpkg -l 'openjdk-*-jdk' 'temurin-*' 2>/dev/null | grep ^ii

Uninstall Java

Remove specific packages—keep the JDK your apps still need:

sudo apt remove --purge openjdk-25-jdk
sudo apt remove --purge temurin-21-jdk
sudo apt autoremove

Remove the Adoptium repository when you no longer use Temurin (see install Temurin on Debian).

After removal, confirm alternatives:

update-java-alternatives --list
java -version 2>&1 || echo "no default java"

Troubleshooting

References

• Debian Wiki — Java
• OpenJDK — install
• DigitalOcean — install Java with apt on Debian
• Oracle Java downloads
• On-site: install Temurin on Debian, install a .deb file, install sudo, apt command, list installed packages

Summary

Install Java on Debian with sudo apt install default-jdk or an explicit openjdk-21-jdk / openjdk-25-jdk when your suite ships it. On Trixie, main provides 21 and 25; use Eclipse Temurin for older majors or when Debian lacks your version. Switch defaults with update-java-alternatives, set JAVA_HOME to the JVM directory, verify with java -version and a javac compile, and remove unused JDK packages with apt remove --purge.