JRE not found, windows

[Nicholas Jankowski]

I have been using Octave on a WInodws 10 PC that didn't have Java
installed. Octave is v5.1.0, zip-package-distribution.

I installed 64bit JRE (not JDK) from here:
https://www.java.com/en/download/

reboot.  java is in the path, CLI version check gives:
C:\>java -version
java version "1.8.0_231"
Java(TM) SE Runtime Environment (build 1.8.0_231-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.231-b11, mixed mode)

checking registry, I see the following is there:
HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment
CurrentVersion --> 1.8

but in Octave I get:

>> version -java
ans = no Java available

>> system("java -version")
java version "1.8.0_231"
Java(TM) SE Runtime Environment (build 1.8.0_231-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.231-b11, mixed mode)
ans = 0


I have deleted and unzipped a fresh copy of Octave. re-ran
'post-install.bat' in case that did something.  No change.  I checked
my other computers where Java works fine, and things seem identical
from what I can see (same reg keys, same install path, etc.) The only
difference is that Octave reports:

octave:1> version -java
ans = Java 1.8.0_231-b11 with Oracle Corporation Java HotSpot(TM)
64-Bit Server VM mixed mode

what am I missing?

nickj