MATLAB: How do you access a single value returned from a JA builder jar

builder jaMATLAB Compiler SDKmwnumericarray

I have a matlab function that returns a single value (or a 1×1 Double)

I have built it into a Jar using JA builder and am calling it from a test java program.

The return type when called from Java is a java.lang.Object[1] – fine so far

When I convert it to using ((MWNumericArray)retVal[0]).getDoubleData() I get a double[0] array!!

There is no value

What am I doing wrong?

Best Answer

I figured out why it was happening - I was passing in my input parameters as java types and assuming that they would be converted.

If I do the conversion myself then the I get a sensible return value that I can access using ((MWNumbericArray)retVal[0]).getDouble()

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MATLAB: How to convert an MWArray returned by the MATLAB Builder NE component to a native .NET array in Visual Basic

ToArray() is a method that is valid only for the MWNumericArray, MWLogicalArray, and MWCharArray types. An element of an MWArray object must be cast to one of these types first before a ToArray() may be issued.

Use the CTYPE Visual Basic function to cast each element of the MWArray array into an MWNumericArray, MWLogicalArray, or MWCharArray, and then call ToArray() on the result. For example, if 'foo' is the MWArray object that contains the various output arguments, the following statement converts the first output argument into a native .NET Double array by way of the MWNumericArray type:

Dim nativeArray(,) As Double = CType(foo(1), MWNumericArray).ToArray(MWArrayComponent.Real)

Refer to the MATLAB Builder NE MWArray Class Library Reference for more details:

https://www.mathworks.com/help/compiler_sdk/cxx/mwarray.html

MATLAB: Help using getmcruserdata and setmcruserdata with JAVA

Hi, Try to create two functions in Matlab that contain getmcruserdata and setmcruserdata:

   function  SetMCRUserData (Value, Key)
   setmcruserdata(Key, Value)
   end %function

and:

   function  Value=GetMCRUserData (Key)
   Value=getmcruserdata(Key);
   end %function

Then, when building the .jar file add these two functions to your class as two methods. (Not in the "Shared Resources" section but in the upper one.)

In Java use them in this way:

   String Key = "MyValue";  
   MyClass.SetMCRUserData(Value, Key);
   Object[] Value =null;  
   Value=MyClass.GetMCRUserData(1, Key);
   System.out.println(((MWNumericArray) Value[0]).getDouble());

This solution worked for me, hope it will help you too.

Best Answer

Related Solutions

MATLAB: How to convert an MWArray returned by the MATLAB Builder NE component to a native .NET array in Visual Basic

MATLAB: Help using getmcruserdata and setmcruserdata with JAVA

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