Java 7 for Gephi – Brief How To

Recurent issue with Gephi is the new Java 8 verison which Gephi does’nt really like. The simple alternative is to keep or reinstall Java 7, but with the high number of people asking for help, it needs to be demystificated.
The procedure I’ll explain is on Windows, but MacOS will be same and Linux user know how to do it

1 – Download Oracle Java

Oracle is actually playing with us, because most of search on google will redirect to the announcement of Java discontinuation and link to Java 8 download. Actually Java 7 is still downloadable, but you need to go to the archive part of the web site here :

Pro Tip :

  • Take the Java SE Runtime Environement 7u65, because it’s the latest one downloadable without login. (I got some feeback where people need to login, it’s free so if you don’t mind you can do it)
  • Don’t download Development Kit, Runtime is enought
  • Download *only* a .tar.gz image, I’ll explain you why it’s important after.

2 – Untar the file

When it’s on your computer, untar (7-zip for Windows, MacOS is native I think) and put somewhere (like C:\Program Files\Java\jre7 or MacOS equivalent)

3 – Specify Gephi which Java version to use

  • Open the file %GephiPath%\etc\gephi.conf
  • Be sure to have the line like this in the file :
jdkhome="C:\Program Files\Java\jre7"

(adapt the path to where you put java)

  • Save the file

Then should be good, launch Gephi and enjoy.


Why this method ?

The .tar.gz file is actually a « transportable » java runtime, it contain the binaries to run the software, and that’s it. No fancy service started for update and etc.

With this method, you can have a default Java 8 version for all your computer and all your applications, but Gephi only will rely on this Java 7.

If you are « reinstalling » Java 7 by replacing Java 8, the default Java version will be an out dated version of java, which expose your system to vulnerabilities & security flaws. And that’s bad.