The fix above works on Windows too but an attempt by the Java runtime to add a key to the Windows registry when Groovy is first launched may give a warning.

Adding the key manually following http://www-01.ibm.com/support/docview.wss?uid=swg21496098 solved that for me (Windows 10 with R2016a).

I have found a relatively simple solution.

If this is an issue with dependencies, we might fix the problem by installing groovy-all-2.4.6.jar at MATLAB startup.

On MATLAB R2016a (on Mac El Capitan for the test) this works if we load either:
1. via a javaclasspath.txt file or
2. by editing classpath.txt

Yair has written about this here.

So, adding Groovy on MATLAB’s static javaclasspath rather than the dynamic path resolves the problem.

An issue may remain with the resolution of dependent jars. If Groovy and MATLAB ship with different versions of a jar file, which gets loaded and which will get used?

Adding Groovy as the first entry in classpath.txt is probably the most robust – but the least attractive – solution. I’d suggest using a javaclasspath.txt file and only editing classpath.txt if problems arise.

Note that if a newer jar file is being loaded and used via Groovy there could be knock-on effects for any code running in the JVM. You will be using a jar file that TMWs production tests have not been run against.

Update:

A quick check with JRE8 shows it does not fix the issue.

Groovy now uses Grape for dependency management:
http://docs.groovy-lang.org/latest/html/documentation/grape.html

The code is fine and works in an external GroovyConsole session so the problem is running it within MATLAB.

Tracking down the problem would likely be difficult and time-consuming.

I’d probably start by swapping to an earlier groovy version.

Then maybe by swapping to the latest JRE 8 release for MATLAB because it’s relatively simple to do and might (but only might) work. There are known issues with some earlier releases of Java 7 and groovy.

If not, a clash between versions of dependencies within groovy and the jars bundled with MATLAB might be the issue.

Example:

>> loader = groovy.lang.GroovyClassLoader();
>> clazz = loader.parseClass('class Foo { }');
>> object = clazz.newInstance();
One or more output arguments not assigned during call to "newInstance".

What could be the problem?

@Donn

There are two sets of jars for Groovy: the “indy” set is for the Java 7 feature users. AFAIK, the standard set should be OK back to Java 5.

It looks like Groovy 2.0 was implemented to take advantage of enhancements in Java 7 while MATLAB through R2012a uses Java 6. This may be why there is trouble using Groovy 2.0 with MATLAB.