Run a java program inside Matlab with a input file.

Hi, I'm tring to run a java program from a matlab code. I already added the .jar file in the system static variables and I achived to lounch the progam. However I need to use a input file wrote inside matlab as a .txt file (or .dat dosen't matter). I'm using the system function:

system('java -jar mhclasses.jar');

system('java -jar javafoil.jar' );

where i can put the input file?

[Kojiro Saito]

It depends on the jar files. Do your jar files allow input argments for a file?

You can check the jar input argments using "--help", possibly.

system('java -jar mhclasses.jar --help')

[luigi ventre]

I'll try thanks!

[luigi ventre]

nothing changes... I recive this message every time i run the script: 'no main manifest attribute, in mhclasses.jar'. The mhclasses.jar is a .jar file that i need to load to run javafoil.jar. On the user guide of this program (javafoil) looks like there is the possibility to run a main script (there are some exemple of java script to run)...

this is one of them:

//

// A simple JavaFoil example which creates a two element

// airfoil for downforce generation.

//

// switch to US country settings

Options.Country(0)

// create a cambered NACA airfoil for starting

Geometry.CreateAirfoil(0;61;15;30;6;40,000;0;0;1)

//

// create a copy of this first airfoil element to be used later

Modify.Select(1)

Modify.Duplicate()

// now select the first element again

Modify.Select(1)

// ... flip it upside down

Modify.Flip(25;0)

// ... scale it to 75%

Modify.Scale(75)

// ... rotate it 5 degrees trailing edge up around its nose (0;0)

Modify.Rotate(0;0;-5)

//

// now select the second element

Modify.Select(2)

// ... flip it upside down

Modify.Flip(25;0)

// ... scale this copy to 30%

Modify.Scale(30)

// ... move it back so that there is 5% overlap

Modify.Move(70.0;12)

// ...rotate it by 30 degrees around a point at (70%/12%)

Modify.Rotate(70;12;-30)

// finally: (THIS IS OMPORTANT!)

// select both elements again for all further analyses

// if only one element is selected on the modify card, only this element

// will be considered during the calculation of polars etc.!

Modify.Select(1;2)

// and move both elements up by 25% for ground clearance

// (note that the airfoil may not cross the y=0 line which is the ground

plane)

Modify.Move(0.0;25)

//

// switch ground effect simulation ON

Options.GroundEffect(1)

//

// prepare for analysis

Options.MachNumber(0)

Options.StallModel(0)

Options.TransitionModel(1)

Options.AspectRatio(0)

// velocity versus x/c should show no strong suction peaks in the

// nose region of 2nd element

Velocity.Analyze(0;0;1;0)

//

// polar for Re=500'000, alfa=-15 to +10 degrees

// with ground present a string suction force is generated

// (even for single element airfoils)

// therefore a Cl_min in the order of -5 to -6 can be seen.

Polar.Analyze(500000;500000;500000;-15;10;1;100;100;0;0)

//

// finally: export coordinates in XML format

Geometry.Save("Z:\groundforce-example.xml")

Onestly this is my first time with java....

Answer 1

[Kojiro Saito]

It might be better to read JavaFoil document.

I'm not familiar with JavaFoil, but it seems that "Script" option allows input files. If you want to input data.txt, try this.

!java.exe -cp "java\mhclasses.jar" -jar "java\javafoil.jar" Script="data.txt"

Alternatively, JavaFoil has embedded sample java code in Embedding and you can use it in MATLAB.

javaFoilPath = "C:\Path\To\MH AeroTools\JavaFoil\java";
javaaddpath(fullfile(javaFoilPath, 'mhclasses.jar'))
javaaddpath(fullfile(javaFoilPath, 'javafoil.jar'))
import MH.JavaFoil.*;
jf = JavaFoil;
% Start JavaFoil embedding
jf.startEmbedded ;
jf.runScriptLine("Options.Country(0)");

% You can input using CreateAirfoil
%jf.runScriptLine("Geometry.CreateAirfoil(0,121,12,30,0.000,40.000,0,0,1)");

% It seems that you can input txt file
jf.runScriptLine("Geometry.Open('data.txt')")

jf.runScriptLine("Polar.Analyze(500000,500000,100000,-5,15,1,100,100,0,0)");
jf.runScriptLine("Polar.Save('polar.txt')"); % Save the result

% Close JavaFoil embedding
jf.exitEmbedded;
clear jf

Again, I'm not familiar with JavaFoil, and it is rather JavaFoil specific question than MATLAB, so if you have further question, I think it's better to ask in JavaFoil community.

[luigi ventre]

you have perfectly answered to my question eaven if you are not practise! thaks!!

I was looking for a method to use javafoil on matlab and save the polars.