public class Schreiber extends Thread {
  Figur f;
  public Schreiber (Figur f) {
    this.f = f;
  }
  public void run () {
    while (true) {
      int  z = (int) (Math.random() * 8); // 0 .. 7
      char x = (char) ('A' + z);          // A .. H
      int  y = 1 + z;                     // 1 .. 8
      f.setPosition(x,y);
    }
  }
}