Question

I installed iplots and rjava packages. When I do this library(iplots), I get the following error. I do have JDK installed on my pc.

Loading required package: rJava
Error : .onLoad failed in loadNamespace() for 'rJava', details:
call: fun(libname, pkgname)
error: JAVA_HOME cannot be determined from the Registry

Error: package ‘rJava’ could not be loaded

Answer 1

The error is telling you that there is no entry in your Registry that tells R where Java is located on your machine. Either your registry is corrupt, but more likely you haven’t installed Java. You can install either the Java Runtime Environment or the Java Development Kit.

(You can download Java here.)

If you installed Java, try reinstalling it. This should put the entries back in your Registry.

If that doesn’t work, you can start looking at exactly where R is looking for your Registry entries. The function that rJava uses to find Java is in the rJava:::.onLoad function. Within that function there is a subfunction called find.java. I copy the contents here:

    find.java <- function() {
        for (root in c("HLM", "HCU")) for (key in c("Software\\JavaSoft\\Java Runtime Environment", 
            "Software\\JavaSoft\\Java Development Kit")) {
            hive <- try(utils::readRegistry(key, root, 2), 
              silent = TRUE)
            if (!inherits(hive, "try-error")) 
              return(hive)
        }
        hive
    }

Copy and paste this into your R window, and then run it find.java(). rJava is looking for an entry for JavaHome. If that isn’t listed, then it is missing from your registry.

You could also manually set the directory of your Java location by setting it before loading the library:

Sys.setenv(JAVA_HOME='C:\\Your\\Java\\Directory')
library(rJava)