🚀 go-pugleaf

Hi, I have the following problem:

Inside an application I call a method, wich reads a File via DataInputStream
(each bit is evaluated and changed), and then written to another File via
DataOutputStream.
Now I want to show the user the progress of the operation using the
jProgressBar.

(this is the methos called:
public static void kodiere(String quelldatei,String zieldatei) throws
IOException {
    FileInputStream quellenlaenge = new FileInputStream(quelldatei);
   int i,laenge= (int) quellenlaenge.available();
   DataInput quelle = new DataInputStream(new FileInputStream(quelldatei));
  DataOutput ziel = new DataOutputStream(new FileOutputStream(zieldatei));





for (i=0;i<laenge;i++){
byte b = (byte) quelle.readByte(); //Einlesen eines Bytes aus der Quelle
       b = (byte) ((b+3)%256);
ziel.writeByte(b);
    }
}

But I can reference the JProgressBar only outside the method, or ?
So can anyone help me how to handle that task?

Thanx
Marcel