MATLAB: How to overcome the Java MCR proxy library initialisation error in Ubuntu

java builderlibrary directorymcrUbuntu

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?

Best Answer

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!
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