Can't import my java class into Matlab

Question

I'm trying to import a custom Java class into matlab. I found this SO Question that I followed.

I have the following Java code

package mypackage.release;
public class TestArgu {
    public void addNumber(int aNumber){
        ansNumber = aNumber+5;
        chk = aNumber;
        System.out.println("input number = " + chk + ".\n");
        System.out.println("ans = " + ansNumber + ".\n");
    }

    public int ansChk(){
        return ansNumber;
    }

    private int ansNumber;
    private int chk;
}

Then I compile with

javac TestArgu.java

I make sure I add the folder that contains the TestArgu.class with javaaddpath('.') file and try to call it with matlab.

>> a = mypackage.release.TestArgu();
Undefined variable "mypackage" or class "mypackage.release.TestArgu".

>> import mypackage.release.*;
>> a = TestArgu();
Undefined function or variable 'TestArgu'.
>> a = mypackage.release.TestArgu.addNumber(1);
Undefined variable "mypackage" or class "mypackage.release.TestArgu.addNumber".

I'm using the same version of java to compile that matlab uses. (JDK 7, Matlab 2013b)

Where am I going wrong ?

Try it: > a = mypackage.release.TestArgu.addNumber(1); – Sergey Morozov Jun 03 '14 at 16:55 — Sergey Morozov, Jun 03 '14 at 16:55
Same thing, added it into the question. – Kassym Dorsel Jun 03 '14 at 17:07 — Kassym Dorsel, Jun 03 '14 at 17:07

score 3 · Accepted Answer · answered Jun 03 '14 at 18:29

I was able to reproduce the same behaviour with the code above. I think one problem is that there is no constructor for this class, so a=TestArgu() will fail. I suggest doing the following. Change the class definition by removing the package my package.release statement and adding a constructor to get

public class TestArgu {

        public TestArgu()
        {
            ansNumber = 0;
            chk       = 0;
        }  

        public void addNumber(int aNumber){
            ansNumber = aNumber+5;
            chk = aNumber;
            System.out.println("input number = " + chk + ".\n");
            System.out.println("ans = " + ansNumber + ".\n");
        }

        public int ansChk(){
            return ansNumber;
        }

        private int ansNumber;
        private int chk;
 }

Compile the code, as before

$ javac TestArgu.java

And then in MATLAB, add the path to wherever this compiled class exists

>> javaaddpath('/Users/geoff/Development/java'); % or wherever

Then instantiate the object

>> a = TestArgu

   a =
       TestArgu@2a307bb2

And try out the method

>> a.addNumber(37)
    input number = 37.

    ans = 42.

Can't import my java class into Matlab

1 Answers1