385

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

Improve this question

3 Answers 3

Reset to default
520

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
Improve this answer
13
  • 2
    When i tried to run Android Studio (that has IntelliJ IDEA as a base), i had an error message very similar to @advocate's: "'tools.jar' seems to be not in Android Studio classpath." After fiddling a lot with JAVA_HOME without success, i decided to take a look at studio.sh, the shellscript that starts Android Studio. As a wild guess, i set JDK_HOME to the same value expected for JAVA_HOME, and voila! It installed without great problems.
    – Hilton Fernandes
    Mar 7, 2015 at 23:20
  • 6
    For those doing software development, don't put your JAVA_HOME in /etc/environment unless you want to reboot everytime you switch JDK versions.
    – Dave
    Sep 20, 2016 at 19:03
  • 3
    This is a temporary solution, as others pointed out. No one would want to run source every time they restart their bash.
    – yuranos
    Feb 19, 2017 at 21:49
  • 7
    As others have pointed out, this doesn't stick between terminal sessions. What I did to address this is just added the line source /etc/environment to the top of my bash config file ~/.bashrc so that it loads all my environment settings on startup. Working for me so far.
    – pje
    Mar 11, 2017 at 22:31
  • 2
    @sedulam I updated the answer
    – Manula Waidyanatha
    Apr 20, 2017 at 6:20
86

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.

Improve this answer
6
  • 7
    How does . /etc/environment work?
    – Sudip Bhandari
    Sep 13, 2016 at 13:36
  • 1
    Is the addition of the export command necessary in the /etc/environment ?
    – pkaramol
    Nov 23, 2016 at 10:01
  • @pkaramol I've had to add export JAVA_HOME on 16.04LTS to make it load at startup.
    – adeen-s
    Jan 20, 2017 at 6:20
  • 4
    @adeen-s You added export to a line in /etc/environment and it helped? That file contains variable definitions parsed as =-delimited name-value pairs; its contents are not executed as commands. (See man pam_env.) So unless you're separately treating the file as though it were a script (such as by passing /etc/environment to bash's ./source builtin), I wouldn't expect that to work.
    – Eliah Kagan
    Aug 17, 2017 at 16:02
  • 1
    > How does . /etc/environment work? -- . (dot) loads commands from a file askubuntu.com/a/232938/189965
    – Roman Bekkiev
    Sep 22, 2018 at 7:32
50

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.

Improve this answer
5
  • 1
    This seems like it would be static. If I remove openjdk-7 and install openjdk-9, won't the JAVA_HOME then point to the wrong place? How can it be made dynamic?
    – DavidJ
    Jul 20, 2016 at 18:49
  • 3
    By you manually changing it. Once again, YOU are the way it becomes dynamic....
    – Dave
    Sep 20, 2016 at 19:04
  • What @HDave means is that In certain cases, you may want JAVA_HOME to point to a specific java version, so making the update of JAVA_HOME dynamic may not be what you want.
    – Maciej
    Oct 9, 2016 at 15:31
  • i like this answer. I tested with echo and see my path. However, I am confused why I am still getting JAVA_HOME environment variable is not set when I run mvn -version
    – Winnemucca
    Apr 11, 2017 at 22:19
  • 3
    I wrote this answer back when I was more ignorant. Setting the variable as described will only affect your current terminal session, and will not be persisted. The correct way is to run update-alternatives --install <link> <name> <target> <priority> for example: update-alternatives --install /usr/bin/java java /usr/lib/jvm/default-runtime/bin/java 1
    – Erro
    May 14, 2017 at 12:26

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .