@Amaury – this seems to be something specific to the MongoClient class. You should probably ask about this in the MongoDB forums.

javaaddpath(Obj.MongoDBPath)
import java.util.ArrayList;
import java.lang.String;
import com.mongodb.*;

credentialsList = ArrayList();
credentials = MongoCredential.createCredential(Username, 'admin' , password);
credentialsList.add(credentials);
mongoClient = MongoClient(ServerAddress(IP,Port), credentialsList);

The failing java class is ServerAdress and is part of the mongodb package.
Other java classes run fine immediately.
This error doesn’t occur on all computers, so I’m giving you my specs.
Windows 10 (previously windows 8), Matlab R2013a with Java 1.6.0_17-b04 (also tried with Java 1.8.0_25-b18 when adding it as environment variable).
It worked on a Mac with Matlab R2015b with Java 1.7, but also failed on another Mac with Matlab R2014a and java 1.8.
Thanks in advance

The class loader will only load one copy of a specific package/class combination. A newer version will not replace the older one even if you have called javaaddpath (hence the NoSuchFieldError which implies you have created an instance using the old code). This is a Java class loader feature: if you load a jar that has dependencies on other jars (e.g. in a /dist/lib folder), and some of those jars are already loaded, the already loaded versions will continue to be used.

In general, open source projects with the Apache brand will maintain backwards compatibility – deprecating, but not removing, old fields/methods. If backwards compatibility is not maintained Apache projects will usually alter the package names so both versions can be used simultaneously. This being the case, replacing the jar file shipped with MATLAB with the newer version should produce no problems. But, anyone else using your code will need to do that too. Buyer beware.

If you wish me to help you debug your specific installation, contact me by mail for a private consulting.

in regard to the first… it shows up on the bottom when I type javaclasspath in the workspace, so I assume it can’t be the wrong file, and that path is what i get when i type prefdir… I definitely restarted Matlab…. and I’m using the same exact file string in the Dynamic path, that I use in the javaclasspath.txt, i just copied it straight from terminal. I’ve done this with no problem on 3 other installs, so it’s a bit strange.

Perhaps one or more of the following happened:

* you edited the wrong classpath.txt file
* you forgot to restart Matlab after editing the classpath.txt file
* you mistyped the class’s full path in the file
* you used a relative path in the file