Overview

Packages
Package	Description
com.mathworks.extern.java	This package provides classes that represent MATLAB struct and cell array datatypes.
com.mathworks.toolbox.javabuilder	This package provides classes that define the rules for data conversion between Java and MATLAB programming environment.
com.mathworks.toolbox.javabuilder.remoting	Contains utilities for exporting MATLAB components over RMI.
com.mathworks.toolbox.javabuilder.web	Contains utilities for writing Java Servlets and JSP pages that use MWArray and WebFigure.
com.mathworks.toolbox.javabuilder.webfigures	Contains classes related to MATLAB WebFigures.

The packages included in javabuilder.jar allow Java programmers to incorporate Java classes created using MATLAB Builder JA in their own JAVA applications. Using MATLAB Builder JA, you can wrap MATLAB functions, from the MATLAB product, into one or more Java classes. Each MATLAB function is encapsulated as a method of a Java class.

NOTE:MATLAB Builder JA is an add-on product to MATLAB that allows conversion of MATLAB code into Java classes. To use MATLAB Builder JA, one also needs MATLAB Compiler which is another add-on product to MATLAB. For more information on these products, please visit www.mathworks.com.

Functionality overview

The packages included in javabuilder.jar, bridge the gap between JAVA and the MATLAB programming environment. These packages provide following important functionalities:

Data conversion between Java and MATLAB data types and vice versa
Utility classes to enable usage of classes created using MATLAB Builder JA in Java RMI based applications
Porting certain aspects of MATLAB graphics in Web based Java applications

MATLAB Compiler Runtime (MCR)

MCR is the collection of platform specific native libraries required to execute MATLAB functions exported by the classes created using MATLAB Builder JA
It can be made available by running MCRInstaller executable. If you install MATLAB, MATLAB Compiler and MATLAB Builder JA, you get MCR automatically. MCRInstaller executable is only needed when these products are not installed
javabuilder.jar is part of MCR and can be found in the $MCR/toolbox/javabuilder/jar directory ($MCR is the root of either MCRInstaller or MATLAB installation)

For more information on MCR, please search the knowledge base at the MathWorks support web site.

MCR, javabuilder.jar and native resources

Though not all, most of the classes included in javabuilder.jar have either direct or indirect dependency on the native libraries included in MCR. Creating the first instance of one of these classes is more time consuming than creating subsequent instances since the native libraries from the MCR get loaded the first time; the subsequent instances of classes are created more quickly since they use the already loaded native libraries. If the underlying MATLAB code is using any graphics functionality offered by MATLAB, there will be additional overhead involved with loading the graphics libraries during the first instantiation of one of the classes.

The operating system uses the native library path to locate native libraries from MCR. See the following list of environment variable names according to operating system:

Operating System	Environment Variable
Windows	PATH
Linux	LD_LIBRARY_PATH
Solaris	LD_LIBRARY_PATH
Macintosh	DYLD_LIBRARY_PATH

For more information on how to set these environment variables to correctly point to MCR, please contact the person who has provided you with javabuilder.jar or visit the MathWorks support web site

Memory management

Due to the dependency on the native resources, special attention should be provided to the memory management associated with the instances of classes from javabuilder.jar. Most of these classes are wrappers that encapsulate some native resources. The JAVA wrapper is smaller in size as compared to the native resources. These native resources exist outside the control of the Java Virtual Machine (JVM). As a result, the JVM memory manager may not call the garbage collector before the native memory becomes exhausted or badly fragmented. So, instances of these classes should be explicitly disposed of as soon as possible by using the appropriate methods provided by those classes. Please refer the Javadoc for the individual packages for more information on the native memory management.

Programming Tips and Techniques

For more information about topics describing advanced integration of MATLAB Builder JA components, see the Programming chapter in the MATLAB Builder JA User’s Guide.