Here is a range of possible solutions for you to explore:
Install the latest rJava version.
Earlier versions may not work! Mirrors are not up-to-date, so go to the source at www.rforge.net: http://www.rforge.net/rJava/files/. Note the advice there
“Please use install.packages('rJava',,'http://www.rforge.net/')
to install.”
That is almost correct. This actually works:
install.packages('rJava', .libPaths()[1], 'http://www.rforge.net/')
Watch the punctuation! The mysterious “.libPaths()[1],”
just tells R to install the package in the primary library directory. For some reason, leaving the value blank doesn’t work, even though it should default.
Tell R about the updated java version
If you just changed your java version, make R aware of this by running R CMD javareconf from terminal.
Add jvm.dll to your PATH and have it in the proper directory
rJava, the R<->Java bridge, needs jvm.dll, but R will have trouble finding it. It resides in a folder like
C:\Program Files\Java\jdk1.6.0_25\jre\bin\server
or
C:\Program Files\Java\jre6\jre\bin\client
Wherever yours is, add that directory to your windows PATH variable. (Windows -> "Path" -> "Edit environment variables to for your account" -> PATH -> edit the value.)
You may already have Java on your PATH. If so you should find the client/server directory in the same Java "home" dir as the one already on your PATH.
It seems that rJava searches for jvm.dll in ~\Java\jre6\bin\client. However this folder didn´t exist on my system (jvm.dll was in ~\bin\server). So one workaround is to make a copy of jvm.dll in a folder ~\bin\client\ and added this to the path.
Define the path for R to find java
options(java.home="C:/Program Files/Java/jre7/")
Change it appropriately
Make sure your architectures match.
If you have Java in Program Files, it is 64-bit, so you ought to run R64. If you have Java in Program Files (x86), that's 32-bit, so you use plain 32-bit R.
Re-launch R from the Windows Menu
If R is running, quit.
From the Start Menu , Start R / RGUI, RStudio. This is very important, to make R pick up your PATH changes.