Use MATLAB Class in Java Application

Overview

This example shows you how to create a Java^® application that calls MATLAB^® wrapper functions for a MATLAB class.

In this example, you perform the following steps:

1. Use MATLAB Compiler SDK™ to create a package that uses MATLAB wrapper functions to access a MATLAB class.

2. Call the MATLAB wrapper functions in a Java application.

3. Build and run the application.

Procedure

1. In MATLAB, examine the MATLAB code that you want to package. For this example, create a MATLAB class named MyMATLABClass.m using the following code:

   classdef MyMatlabClass < handle
       
       properties (Access = private)
           x % input variable
           y % input variable
           z % result variable
       end
       
       methods
           function this = MyMatlabClass()
               this.x = []; this.y = [];
           end
           
           function setInput(this, input)
               input = input(:);           
               if isnumeric(input) && numel(input) == 2
                   this.x = input(1);
                   this.y = input(2);
               end
           end
           
           function result = getResult(this)
               result = this.z;
           end
           
           function status = compute(this)
               try
                   this.z = (this.x.^2 + this.y.^2)^0.5;
                   status = true;
               catch
                   status = false;
               end
           end
       end
       
   end

2. Create four MATLAB wrapper functions for the class: CreateMyMATLABClass.m, SetInput.m, Compute.m, and GetResult.m.

   CreateMyMATLABClass.m.  

   function instance = CreateMyMATLABClass()
       instance = MyMATLABClass();
   end

3. Build the Java package with the Library Compiler app or compiler.build.javaPackage using the following information:

   Field	Value
   Library Name	MyMATLABClass1
   Class Name	Class1
   Files to Compile	CreateMyMATLABClass.m SetInput.m Compute.m GetResult.m

   For example, if you are using compiler.build.javaPackage, type:

   buildResults = compiler.build.javaPackage(["CreateMyMATLABClass.m", ...
   "SetInput.m","Compute.m","GetResult.m"], ...
   'PackageName','MyMATLABClass1', ...
   'ClassName','Class1');

   For more details, see the instructions in Generate Java Package and Build Java Application.

   Note

   You do not need to manually add the MyMATLABClass.m file to the package, as the compiler automatically includes it during dependency analysis.

4. Navigate to the folder that contains the generated MyMATLABClass1.jar package. If you used the Library Compiler, the package is in the for_testing folder.

5. Write source code for an application that accesses the MATLAB functions. The code for this example is provided below.

    javadriver.java

   /* Necessary package imports */
   import com.mathworks.toolbox.javabuilder.*;
   import java.util.*;
   import MyMATLABClass.*;
   
   class javadriver
   {
   	public static void main(String[] args)
   	{
   		try
   		{			
   			System.out.println("--- USE: Constructors ---");
   			/* Instantiate a new Java object */
   			/* This should only be done once per application instance */
   			MyMATLABClass1.Class1 obj = new MyMATLABClass1.Class1();
   			
   			Object[] a = obj.CreateMyMATLABClass(1);
   			obj.SetInput(a[0],new double[]{1,2});
   			Object[] b = obj.Compute(1,a[0]);
   			System.out.println( (MWLogicalArray) b[0]);
   			Object[] c = obj.GetResult(1, a[0]);
   			System.out.println((MWNumericArray)c[0]);        
   			System.out.println("--- Done. ---");
   		}
   		catch (Exception e)
   		{
   		System.out.println("Exception: " + e.toString());
   		}    	
   		finally
   		{
   		}
   	}
   }

6. Open a command prompt window and navigate to the folder that contains javadriver.java and MyMATLABClass.jar.

7. Compile the javadriver.java application using javac.

   • On Windows^®, type:

     javac -classpath "matlabroot\toolbox\javabuilder\jar\javabuilder.jar";.\MyMATLABClass.jar javadriver.java

   • On UNIX^®, type:

     javac -classpath "matlabroot/toolbox/javabuilder/jar/javabuilder.jar":./MyMATLABClass.jar javadriver.java

   Replace matlabroot with the path to your MATLAB or MATLAB Runtime installation folder. For example, on Linux^®, the path may be /usr/local/MATLAB/R2024b.

8. Run the javadriver application.

   On Windows, type:

   java -classpath .;"matlabroot\toolbox\javabuilder\jar\javabuilder.jar";.\MyMATLABClass.jar javadriver

   On Linux, type:

   java -classpath .:"matlabroot/toolbox/javabuilder/jar/javabuilder.jar":.\MyMATLABClass.jar javadriver

   Note

   If you are running the application on the Mac 64-bit platform, you must add the -d64 flag in the Java command.

The javadriver program displays the following output:

--- USE: Constructors --- 
1 
2.2361 
--- Done. ---