Comment exécuter un programme C++ à partir d'une interface Java?

Bonjour,

Je commence à programmer en C++. J'ai écrit un programme Java, et je lance un programme C++. Ma question est la suivante une fois les variables définies dans l'interface Java, quelle écriture dans le programme Java va permettre de recopier ces valeurs dans le programme C++
Ci-joint mon programme.
Je vous remercie par avance.

import java.awt.*;  //file gui.java
import java.io.*;
import java.awt.event.*;

public class gui extends Dialog implements MouseListener
{
    String dfname = "project.txt", gridname ;
    int offset = 80, hmax =380 , vmax =180, downoffset = 40 + offset;
    Button loadtriau, runjob;
    boolean mesh=false;
    TextField textfield0,textfield1,textfield2,textfield3;
    Label rhs, temper ;
    String rhsval="x+y", temperval="200";
    Checkbox checkbox0, checkbox1;
    CheckboxGroup pbcheckboxes;
    int dwhat0=1;
       
public  gui(Frame parent) {
        super(parent, "Project Data Input Interface", false);
        this.setSize(hmax+2*offset, vmax+4*offset);
}

public class  getfilename extends Frame{
  FileDialog fd;
  public String fname;
    public getfilename() { }
    public String getthename(){  
        fd = new FileDialog(this, "Choose a mesh",FileDialog.LOAD);
        fd.setVisible(true);
        fname = fd.getFile();
        return fname;
    }
}

public void myinterface(){
        this.setLayout(new FlowLayout());       
        loadtriau = new Button("Load Mesh");this.add(loadtriau);
        runjob = new Button("Run Job");      this.add(runjob);
        rhs = new Label("f =");
        textfield0 = new TextField(rhsval,20) ;
        this.add(rhs);                      this.add(textfield0);
        temper = new Label("rho =");
        textfield3 = new TextField(temperval,20) ;
        this.add(temper);             this.add(textfield3);
        pbcheckboxes = new CheckboxGroup();
        checkbox0 = new Checkbox("Explicite",pbcheckboxes,dwhat0==1);
        checkbox1 = new Checkbox("Implicit",pbcheckboxes,dwhat0==0);
        this.add(checkbox0);               
        this.add(checkbox1);
        this.pack();       
        Graphics g = this.getGraphics();   
        loadtriau.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){ 
                getfilename ff = new getfilename();
                gridname = ff.getthename();
                mesh = true;
            }
        }); 
        runjob.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
               savemyparam();
            String line;
            Runtime rt = Runtime.getRuntime();
                    try{
            System.out.println("exec : on lance la partie C++");
            Process  ax = rt.exec("./a.out");
            InputStream ao = ax.getInputStream() ;
            BufferedReader br = new BufferedReader(new InputStreamReader(ao));
              while (( line= br.readLine()) != null) {
                System.out.println(line);
              }
            }
                        catch (IOException Ex){
                System.out.println("catch execption exec ");
                                System.out.println(Ex.getMessage());
                System.exit(1);            
                }
                System.out.println(" Exit normal  ");
                    System.exit(0);            
              }
        });
        this.addMouseListener(this);
        addMouseListener(this);
}

public void savemyparam()
    {   String rhsval = textfield0.getText();
        String temperval = textfield3.getText();
        try{
            FileOutputStream filename=
            new FileOutputStream(dfname);
            PrintStream ffile = new PrintStream(filename);
            ffile.println(rhsval);
            ffile.println(temperval);
            if(checkbox0.getState()) ffile.println("0");
                else ffile.println("1");
            if(mesh) ffile.println(gridname);
         }
        catch (IOException Ex)
        {
            System.out.println(Ex.getMessage());
        }
    }  
   
public void paint( Graphics g ) {;}          
public void mousePressed(MouseEvent e) {;}
public void mouseReleased(MouseEvent e){;}         
public void mouseEntered(MouseEvent e) {;}
public void mouseClicked(MouseEvent e) {;}
public void mouseExited(MouseEvent e)  {;}

public static void main(String[] args){
        Frame f = new Frame("Java Project Interface");
        gui b = new gui(f);
        b.myinterface();
        b.setSize(840,300);
        b.setVisible(true);
       
    }
}