public SubCategory(int id, String naam, int datatype, float weight, int red, int green, int blue, boolean selected)
  {
    this.id = id;
    this.naam = naam;
    this.datatype = datatype;
    this.weight = weight;
    this.selected = selected;
    this.red = red;
    this.green = green;
    this.blue = blue;
    this.periods = new ArrayList<Period>();
  }