Problems when trying to load a package in R due to rJava

Question

When I type require(xlsx) in order to load the package xlsx in R, the following messages is shown:

> require(xlsx)
Loading required package: xlsx
Loading required package: xlsxjars
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
Failed with error:  ‘package ‘rJava’ could not be loaded’

I've also tried to load the rJava package manually but got this error message:

require(rJava)
Loading required package: rJava
Error : .onLoad failed in loadNamespace() for 'rJava', details:
  call: fun(libname, pkgname)
  error: No CurrentVersion entry in Software/JavaSoft registry! Try re-installing Java and make sure R and Java have matching architectures.

Do you have any suggestion on how to solve the problem?

Answer 1

The reason is probably linked to the fact you are using a 64-bit OS and R version but do not have Java installed with the same architecture. What you have to do is to download Java 64-bit from this page: https://www.java.com/en/download/manual.jsp

After that just try to reload the xlsx package. You shouldn't need to re-start R.