I recently installed Mars Eclipse. I took the default install directory, c:\users\myname\eclipse\java-mars. Everything is installed and some projects checked out and working.
But I now wish I had installed it in c:\eclipse\java-mars. I am wondering how to change it? Please note I did searches but they all are how to move your workspace, not how to change the installation directory. My workspace can stay where it is. I suppose I could uninstall and delete everything, and reinstall into a new directory, but that is a lot of hassle.
You just have to move the eclipse folder to the new location. There's no need to change anything in the PATH variable because this thing is only needed by eclipse itself to locate the java environment.
Note:
If you have any third-party librarys inside the eclipse folder that are used by eclipse during it's runtime there may be an error because eclipse only stores an absolute path to them in it's config files. So in that case, you have to change the path to such libraries in the eclipse settings, I think at the same point where you have added them.