I was originally using static it looked something like this

public class NativeLinker{

  public native static void SetVal(double a_newVal);   
  public native static double GetVal();   

  static
  {
    System.loadLibrary("tankDLL");
  }
}
   

It worked fine.
But I am now Trying to change it to something like This :

public class TankModel{
  public native void SetVal_LIB(double a_newVal);   
  public native double GetVal_LIB();   

  public TankModel(){
    System.loadLibrary("tankDLL");
  }

  public void SetVal(double d) {
    SetVal_LIB(d);
  }
  public double GetVal() {
    return GetVal_LIB();
  }
}
...
//Then I Make Some Tanks , at some point
TankModel tank_A = new TankModel();
TankModel tank_B = new TankModel();

tank_A.SetVal(1.23);
tank_B.SetVal(3.21);
System.out.println(tank_A.GetVal());
System.out.println(tank_B.GetVal());

I hope this makes it clear.
I am trying to make every Instance of TankModel hold its own state in a
separate library.
The original Fortran Code was made to be a command line exe that ran and
 only ever had 1 tank, and comunicated with the user with flat files.
So it only ever had to store a single tank state.

It is now a dll and We can dynamically change its current state in java.
But, I can't Get it to hold many different states.

In fact `TankModel` currently behaves exactly like`NativeLinker`, it
behaves like GetVal and SetVal are static functions.
I was hoping for a way around this..

Thanks again.

how

I am not so sure I want this.
I want to be able to communicate with the Model in a dynamic way.
I am not sure I/O streams would be efficient.

I thought the JNI was the best way to go.
I am open to other suggestions if you have some.

At any rate, the conversion to DLL is mostly already done.
and all the required access methods exist.
At this point I need a way to make several Instances of it.