无法在 Octave 中使用 Java

Question

I'm using Octave 4.2.1 on Windows 10. When I type in the Octave console:

>> __have_feature__ JAVA
ans = 1

So java is enabled. Using the Command Prompt on Windows I found that I have java version "1.1.0_71". So java is present and running. But when I try to call a java fuction in Octave I get:

cp = javaclasspath
error: unable to find Java Runtime Environment: software\javasoft\java runtime environment::Currentversion

And when I just type 'java -version':

>> java -version
error: 'java' undefined near line 1 column 1

I checked the environment variable for java:

>> getenv JAVA_HOME
ans = C:\Program Files\Java\jdk1.7.0_71

Again, this looks fine. FInally I even tried to install Octave from scratch, but this did not solve the issue. My guess is that it has something to do with the 'software\\javasoft\\java runtime environment::CurrentVersion' but I'm unable to figure out what it is.

Answer 1

This is likely connected to the difference of the bitness of Octave and your JRE. This post raises the same issue. That one was resolved by bringin the Octave bitness into line with JRE bitness. Make sure your Octave installation is 64-bit.

It is also worth checking you have the following variable specified:

Answer 2

I suppose you run the 64-bit version of Octave and you have the 64 bit version of JDK 11.0.5

In file octave.vbs write after line

Set wshShell = CreateObject( "WScript.Shell" )

the line

wshShell.Environment("SYSTEM")("JAVA_HOME") = "c:\program files\java\jdk-11.0.5"

Then merge the following registry lines with your registry

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment]
"CurrentVersion"="11.0.5"

[HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment\11.0.5]
"JavaHome"="C:\\Program Files\\Java\\jdk-11.0.5"
"RuntimeLib"="C:\\Program Files\\Java\\jdk-11.0.5\\bin\\client\\jvm.dll"

*** EDIT: The code above, is for Windows 7. If you run Windows 10, change "client" with "server":

    "RuntimeLib"="C:\\Program Files\\Java\\jdk-11.0.5\\bin\\server\\jvm.dll"