public boolean equals(Object object) {
		if (object instanceof ActivityNode) {
			ActivityNode actNode = (ActivityNode) object;
			if ((this.activity == null || actNode.getActivity() == null) && 
					!(this.activity == null && actNode.getActivity() == null)) {
				return false;
			}
			if (this.nodeNr != actNode.nodeNr) {
				return false;
			}
			if (this.activity != null && actNode.getActivity() != null && 
					!this.activity.equals(actNode.getActivity())) {
				return false;
			}
			return true;
		}
		return false;
	}