Call a java function from matlab script

Question

I'm trying to call a java function from a Matlab script, I tried all the solutions put in the website but I didn't get an issue. My class is simple:

  package testMatlabInterface;

public class TestFunction
{
  private double value;

  public TestFunction()
  {
      value=0;
  }

  public double Add(double v)
  {
      value += v;
      return value;
  }

  public static void main(String args[])
  {

  }
}

So I put .java file (also .class) in my workingspace C:\scriptsMatlab and I added this path to javaclasspath of Matlab, but when I try to call the function , it tells me that there's no class with this name in javaclasspath of Matlab.

EDIT: Here's the version of java that Matlab uses:

Java 1.6.0_17-b04 with Sun Microsystems Inc. Java HotSpot(TM) Client VM mixed mode

And this is the version on jdk which I used to compile my class :

But when I try to execute this commande from matlab

>> javaaddpath 'C:\scriptsMatlab'
>> obj = TestFunction

it tells me:

Undefined function or variable 'TestFunction'.

Probably need single quotes for the argument. What happens if you try `import MyFunction.*`? — mhopeng, May 02 '16 at 18:27
I tried to follow the answer of macduff here http://stackoverflow.com/questions/9520503/calling-java-from-matlab but i get stuck in ' methodsview testMatlabInterface.TestFunction' it says that 'No class testMatlabInterface.TestFunction can be located or no methods for class' — Eadhun Di, May 02 '16 at 18:50
which java version did you use to compile your class? It's best to use the same major version as your Matlab uses, otherwise it may not work. — nirvana-msu, May 02 '16 at 19:57
It's the same version, you can see my question after editing it — Eadhun Di, May 03 '16 at 18:16

score 0 · Accepted Answer · edited Jun 20 '20 at 09:12

0

Option 1

Check if same JRE/JDK is being used to compile your JAVA file. Execute on Matlab:
```
version -java
```
Compie your MyFunction.java with same jdk as above , and locate your MyFunction.class
Locate your Matlab classpath.txt. Type following into matlab cmd.
```
which classpath.txt
```
Open your classpath.txt as administrator.Add the full path for the directory with the MyFunction.class to the end of the 'classpath.txt' file as a single line and save the file.
Restart Matlab.
To run in Matlab . Create object of MyFunction.
```
obj = MyFunction
```
To run main() method in matlab.
```
javaMethod('main', obj, '')
```

Option 2

Follow Steps 1-2.

Execute following command in Matlab

JAVAADDPATH PATH/to/Directoryof MyFunction.class.

No need to restart Matlab here. Just run using

obj = MyFunction;
javaMethod('main', obj);

From MathWorks :

javaMethod(MethodName,JavaObj,x1,...,xN) calls the method in the class of the Java® object array with the signature matching the arguments x1,...,xN.

javaMethod(StaticMethodName,ClassName,x1,...,xN) calls the static method in class ClassName.

edited Jun 20 '20 at 09:12

Community

1
1

answered May 02 '16 at 20:58

Sid

115
1
12

Should you not call obj = MyFunction . What is TestFunction ? – Sid May 06 '16 at 20:54
Sorry I just changed the test function with another – Eadhun Di May 08 '16 at 17:36
did you follow option 1 ? add testfunction.class with package directory to your matlab cp ? – Sid May 08 '16 at 19:45
1

Classpath is not being added properly . Check javaclasspath. also try following javaaddpath('directory where the .class file resides'); a = TestFunction(); //Creates an object of the java class. methodsview(a); // displays all the methods. a.Add() ; calls the Java method Add(). After you add classpath check classpath.txt of matlab , does it have the cp of .class file. Also remove the .java in the directory. only keep the .class in the classpath – Sid May 08 '16 at 21:01
It's bizarre that there isn't something more convenient than this. – Dave C Sep 18 '17 at 18:26

Call a java function from matlab script

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