How do I overcome the Java MCR proxy library initialisation error in Ubuntu?

I would like to run a jar, which was built with Matlab's Java Builder on Windows 7 in Ubuntu 14.04 using the MCR libraries. However, I am receiving the following error when testing the MCR installation for an App built with Java Builder:

 sudo java -classpath "/opt/MCR/v84/toolbox/javabuilder/jar/javabuilder.jar:/media/sf_shared/for_testing/makesqr.jar" makesqr.Class1 5 

 java.lang.ExceptionInInitializerError
  at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration.getProxyLibraryDir(MCRConfiguration.java:260)
  at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration$MCRRoot.get(MCRConfiguration.java:71)
  58)
        ...
  at makesqr.Class1.main(Class1.java:112)
Caused by: java.lang.NullPointerException
  at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration$ProxyLibraryDir.get(MCRConfiguration.java:225)
  at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration$ProxyLibraryDir.<clinit>(MCRConfiguration.java:255)
  ... 10 more

In order to reproduce the error, or to discover where I went wrong, here are all the steps I have done:

Background: I have created an Ubuntu VirtualBox from LAPP stack and added the Ubuntu desktop (Unity: sudo apt-get install ubuntu-desktop). Now I am attempting to install the MCR.

• Download MCR zip and extract to MCR_SOURCE
• Go to my folder that contains the files: cd /media/sf_shared/MCR_ SOURCE
• Change installer_input.txt file:

 destinationFolder=/opt/MCR
 agreeToLicense=yes
 outputFile=/opt/install.log
 mode=silent
 product.MATLAB
 product.MATLAB_Builder_JA
 # Note: To find out the required toolboxes >> start Matlab >> run your code and find out which toolboxes were used with: license('inuse')

• Install MCR: sudo ./install -inputFile /media/sf_shared/MCR_SOURCE/installer_input.txt >> success
• Note changing the /etc/environment file removes the sidebar from my Ubuntu desktop (another issue), so instead I am exporting the variables directly to a terminal. (Note: X11/app-defaults folder does not exist)

 export LD_LIBRARY_PATH="/opt/MCR/v84/runtime/glnxa64:/opt/MCR/v84/bin/glnxa64:/opt/MCR/v84/sys/os/glnxa64:${LD_LIBRARY_PATH}"
 export XAPPLRESDIR="/opt/MCR/v84/X11/app-defaults"

• Change the ownership of the /opt/MCR folder to my user name: sudo chown -R my-user-name:root /opt/MCR/
• Relax file and folder permissions for the /opt/MCR/ folder: sudo find /opt/MCR -type f -exec chmod 775 {} \; and sudo find /opt/MCR -type d -exec chmod 775 {} \;
• Install Java on Ubuntu: sudo apt-get install openjdk-7-jre; check existence with java-version (see here for details).
• Create the Java package makesqr as explained in "Matlab's JavaBuilder tutorial". This step is done on my Windows 7 machine, which runs Matlab R2014b (asserted that this is in accordance with the downloaded MCR earlier on). Matlab ver states that Java Version: Java 1.7.0_11-b21 with Oracle Corporation Java HotSpot™ 64-Bit Server VM mixed mode is used, and MATLAB Builder JA (Version 2.3.2).
• Test that it runs in Windows:

C:\>java -classpath "C:\MATLAB\R2014b\toolbox\javabuilder\jar\javabuilder.jar";C:\MATLAB\R2014b\work\makesqr\for_testing\makesqr.jar makesqr.Class1 5

ans =

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9

• Make the package available to Ubuntu: I have copied the for_testing directory to a folder that my Ubuntu VM and Windows machine share. (double check ownership and permissions - similar to MCR folder step)
• Test MCR with Java:

   sudo java -classpath "/opt/MCR/v84/toolbox/javabuilder/jar/javabuilder.jar:/media/sf_shared/for_testing/makesqr.jar" makesqr.Class1 5

This is where the above mentioned error message occurs. The error message indicates that the MCRConfiguration$ProxyLibraryDir cannot be obtained.

• What is this MCR configuration library directory?
• Do I need to add "this folder" to the classpath?
• Is something wrong of how the LD_LIBRARY_PATH or XAPPLRESDIR were set?

Answer 1

[Wolfgang Garn]

Thanks to Martijn's (Mathworks) prompt response. We have now two solutions that work:

1. _"Please try running your application as normal user without sudo."
2. "Or alternatively use "sudo -i" to get an interactive su session, in there use "export LD_LIBRARY_PATH=…." and then try running the application from here."

The first one meant for me simply:

java -classpath "/opt/MCR/v84/toolbox/javabuilder/jar/javabuilder.jar:/media/sf_shared/for_testing/makesqr.jar" makesqr.Class1 5

The second solution:

sudo -i
export LD_LIBRARY_PATH="/opt/MCR/v84/runtime/glnxa64:/opt/MCR/v84/bin/glnxa64:/opt/MCR/v84/sys/os/glnxa64:${LD_LIBRARY_PATH}"
export XAPPLRESDIR="/opt/MCR/v84/X11/app-defaults"
java -classpath "/opt/MCR/v84/toolbox/javabuilder/jar/javabuilder.jar:/media/sf_shared/for_testing/makesqr.jar" makesqr.Class1 5

Both of them worked for me!

[David Clifford]

Hi, I was wondering how you might apply this solution to a Webapp (tomcat7) that uses Matlab created jar files? I get the exact same error on my Catalina.out. Can I start tomcat with the same parameters you used above (root, classpath,etc)?

Thanks in advance