Calling matlab from java, java.lang.UnsatisfiedLinkError

I am trying to call a matlab function I have from java (developing in Eclipse). I can get it to run just fine with R2019b, but when I change the java build path to R2019a (engine.jar - C:\Program Files\MATLAB\R2019a\extern\engines\java\jar), I get an error:

Caused by: java.lang.UnsatisfiedLinkError: com.mathworks.mvm.MvmFactory.nativeSetJavaEngine(Z)V
	at com.mathworks.mvm.MvmFactory.nativeSetJavaEngine(Native Method)
	at com.mathworks.mvm.MvmImpl.setJavaEngineMode(MvmImpl.java:203)
	at com.mathworks.engine.MatlabEngine.<clinit>(MatlabEngine.java:69)
	at MyController.onRunSimClick(MyController.java:190)
	... 62 more

I have added both C:\Program Files\MATLAB\R2019b\bin\win64 and C:\Program Files\MATLAB\R2019a\bin\win64 to my PATH variable.

The start of the stack trace is:

java.lang.NoSuchMethodError: Method com.mathworks.mvm.MvmFactory.nativeCreateFactory(IIZ[Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;[Ljava/lang/String;[Ljava/lang/String;)J not found

I am happy to provide the rest, but don't want to create clutter. Thanks in advance!

I cannot comment yet, so putting this in as an answer. The first thing you might want to do is run:

java -XshowSettings:properties -version

to see what your java.library.path is.

I found a workaround, where I can just compile and run my code from the command line. I had to add C:\Program Files\MATLAB\R2019a\bin\win64; to my path before any other matlab version. Then, as per the matlab documentation I could just do:

> javac -classpath matlabroot\extern\engines\java\jar\engine.jar MyJavaCode.java
> java -classpath .;matlabroot\extern\engines\java\jar\engine.jar MyJavaCode

I'm still not sure why this wouldn't work in Eclipse, but this workaround will work for the short term.