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I've installed a version of Java. How can we set the $JAVA_HOME environment variable correctly?

kiri
  • 28,986
Gaurav Agarwal
  • 11,913

4 Answers4

536

You can set your JAVA_HOME in /etc/profile as Petronilla Escarabajo suggests. But the preferred location for JAVA_HOME or any system variable is /etc/environment.

Open /etc/environment in any text editor like nano or gedit and add the following line:

JAVA_HOME="/usr/lib/jvm/open-jdk"

(java path could be different)

Use source to load the variables, by running this command:

source /etc/environment

Then check the variable, by running this command:

echo $JAVA_HOME

Update

Usually most linux systems source /etc/environment by default. If your system doesn't do that add the following line to ~/.bashrc (Thanks @pje)

source /etc/environment
Zanna
  • 72,312
Manula Waidyanatha
  • 8,755
88

To set JAVA_HOME environment variable, do the following:

  1. Launch Terminal by pressing Ctrl+Alt+T on your keyboard.
  2. Enter the following command:
    $ gksudo gedit /etc/environment
  3. Depending on where you installed your Java, you will need to provide the full path. For this example, I installed Oracle JDK 7 in the /usr/lib/jvm/java-7-oracle directory.
    Scroll to the end of the file and enter the following:
    JAVA_HOME=/usr/lib/jvm/java-7-oracle
    export JAVA_HOME
  4. Save your file and exit gedit.
  5. Lastly, reload the system PATH with the following command:
    $ . /etc/environment

The above method will save you the hassle in having to run the commands every time you log in to your computer.

Petronilla Escarabajo
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52

If you do not know the path and you only have openJDK installed, you can type update-alternatives --config java and you should find the path. To set the variable you can write JAVA_HOME=<PATH> followed by export JAVA_HOME. Notice there's no space when declaring the variable. To check if the variable is stored you simply type echo $JAVA_HOME to verify.

Erro
  • 899
4

This is the best option if you always want to use the latest one installed.
Nowadays (Ubuntu 23.10) you should probably have it installed through apt like:

sudo apt install default-jdk # or default-jre

In this case, you should find it at /usr/lib/jvm/default-java.
It's a symlink that points to whichever the current JVM is on the same folder.
So, just run this to add the environment as a separate file:

sudo nano /etc/environment.d/90java.conf

Add this line and save:

JAVA_HOME="/usr/lib/jvm/default-java"

Then reboot or login again, or source /etc/environment.d/90java.conf to load it on the current shell.

geekley
  • 697