How to avoid infinite loop in Observer pattern?

Question

I have only one class with many instances. Every instance is observer of couple of other instances. As well every instance can be observable by couple of another instances.<

Answer 1

If your system is single threaded, then you simply need a guard inside your notify method:

private boolean _notifying;

public void notify() {
  if(_notifying) {
    return;
  }
  _notifying = true;
  try {
    // ... do notifying here...
  } finally {
    _notifying = false;
  }
}