I have Libre Office installed on Mac OS X installed and it only found the old Java 6 installation. No matter which path I enter it is not a valid Java installation directory.
It is of course. The test used is just to strict.
So what is a valid Java installation? Which test are performed?
I would like to know, too, because I recently installed Java 7 and wondered how I could change to it in LibreOffice, on OS X 10.8.
It does not take the Java 7 path because it’s 64bit and LibO 4.1 does not support 64bit yet. It will be available in 4.2, see this answer
For what it’s worth, I just installed JRE 1.8.0u5 and LibreOffice 4.2.5 on my Mac running OS X 10.9. The Oracle 1.8.0_05 JRE and the Apple 1.6.0_65 JRE both appear in the list of JREs in Preferences → LibreOffice → Advanced. I don’t have a way to give it a good workout but at least I can choose the new JRE.