Problem installing Java package

[Joao Rodrigues]

I want to use package io which I tried to install as (inside the 
interpreter):

pkg install -forge io

But then when I tried to use xlsread no interfaces were founded. 
Googling suggested that the java package should also be installed and 
load before the io one. I promptly typed:

pkg install -forge java

And got a lot of errors starting with:

Error while trying to install Java package:
environment variable 'JAVA_HOME' has not been set.
  use 'setenv ("JAVA_HOME", "/full/path/to/javaJDK")'
  Hint:
  JAVA_HOME should usually be set such that either:
  (on *nix:)
    <JAVA_HOME>/jre/lib/<arch>/client/ contains libjvm.so (file or symlink)

I went to the root in another terminal and did:

sudo find . -name 'libjvm.so'

and found:

./usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/server/libjvm.so
./usr/lib/jvm/java-1.5.0-gcj-4.9-amd64/lib/libjvm.so
./usr/lib/x86_64-linux-gnu/gcj-4.9-15/libjvm.so

Then back at the interpreter:

setenv ("/usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/server/", 
"/full/path/to/javaJDK")
pkg install -forge java

or

setenv ("/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64/lib/", 
"/full/path/to/javaJDK")
pkg install -forge java

or

setenv ("/usr/lib/x86_64-linux-gnu/gcj-4.9-15/", "/full/path/to/javaJDK")
pkg install -forge java

But I always got the same error. Is the "/full/path/to/javaJDK" also a 
place holder to be replaced with something else? Some other dependency 
missing?

System: Ubuntu 14.10

Help appreciated