Problem with Java Mac

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Hi,

I'm having problems installing Deducer for R on my Mac. I need it for my college stats course. 

I'm running macOS Catalina 10.15.2

I've downloaded R and followed the instructions:

• Download and install R from here
• Open R and install Deducer by entering:

install.packages(c("JGR","Deducer","DeducerExtras"))

Which gives me

There are binary versions available but the source versions are
  later:
         binary source needs_compilation
mvtnorm  1.0-11 1.0-12              TRUE
multcomp 1.4-11 1.4-12             FALSE

Do you want to install from sources the package which needs compilation? (Yes/no/cancel) No
trying URL 'https://cran.ma.imperial.ac.uk/bin/macosx/el-capitan/contrib/3.6/mvtnorm_1.0-11.tgz'
Content type 'application/x-gzip' length 261813 bytes (255 KB)
==================================================
downloaded 255 KB

trying URL 'https://cran.ma.imperial.ac.uk/bin/macosx/el-capitan/contrib/3.6/JGR_1.8-6.tgz'
Content type 'application/x-gzip' length 1150184 bytes (1.1 MB)
==================================================
downloaded 1.1 MB

trying URL 'https://cran.ma.imperial.ac.uk/bin/macosx/el-capitan/contrib/3.6/Deducer_0.7-9.tgz'
Content type 'application/x-gzip' length 3245379 bytes (3.1 MB)
==================================================
downloaded 3.1 MB


The downloaded binary packages are in
	/var/folders/jn/6jk4gspj13db33flb93qsyjh0000gn/T//Rtmp7pdPOy/downloaded_packages
installing the source package ‘multcomp’

Then in Packages & Data > Package manager > choosing Deducer I get:

trying URL 'https://cran.ma.imperial.ac.uk/src/contrib/multcomp_1.4-12.tar.gz'

Content type 'application/x-gzip' length 609805 bytes (595 KB)

==================================================

downloaded 595 KB

* installing *source* package ‘multcomp’ ...

** package ‘multcomp’ successfully unpacked and MD5 sums checked

** using staged installation

** R

** data

*** moving datasets to lazyload DB

** demo

** inst

** byte-compile and prepare package for lazy loading

Error in loadNamespace(i, c(lib.loc, .libPaths()), versionCheck = vI[[i]]) : 

  there is no package called ‘zoo’

Calls: <Anonymous> ... loadNamespace -> withRestarts -> withOneRestart -> doWithOneRestart

Execution halted

ERROR: lazy loading failed for package ‘multcomp’

* removing ‘/Library/Frameworks/R.framework/Versions/3.6/Resources/library/multcomp’

The downloaded source packages are in

‘/private/var/folders/jn/6jk4gspj13db33flb93qsyjh0000gn/T/Rtmp7pdPOy/downloaded_packages’

Warning messages:

1: package ‘DeducerExtras’ is not available (for R version 3.6.2) 

2: In install.packages(c("JGR", "Deducer", "DeducerExtras")) :

  installation of package ‘multcomp’ had non-zero exit status

Loading required package: JGR

Loading required package: rJava

Error: package or namespace load failed for ‘rJava’:

 .onLoad failed in loadNamespace() for 'rJava', details:

  call: dyn.load(file, DLLpath = DLLpath, ...)

  error: unable to load shared object '/Library/Frameworks/R.framework/Versions/3.6/Resources/library/rJava/libs/rJava.so':

  dlopen(/Library/Frameworks/R.framework/Versions/3.6/Resources/library/rJava/libs/rJava.so, 6): Library not loaded: /Library/Java/JavaVirtualMachines/jdk-11.0.1.jdk/Contents/Home/lib/server/libjvm.dylib

  Referenced from: /Library/Frameworks/R.framework/Versions/3.6/Resources/library/rJava/libs/rJava.so

  Reason: image not found

Error: package ‘rJava’ could not be loaded

In addition: Warning message:

In system("/usr/libexec/java_home", intern = TRUE) :

  running command '/usr/libexec/java_home' had status 1

Unable to find any JVMs matching version "(null)".

No Java runtime present, try --request to install.

I've already updated Java and can't figure out how to resolve this. I've looked through previous posts but really don't understand the different coding that people have posted for a fix. I'm definitely not coding literate.

Can anyone help? Do I need to somehow revert to an older pre-Oracle version of Java?

Thanks for your time.