private String getActiveModels() {
        String s = "";
        int modelNumber = 0;
        int num = 0;
        while (modelNumber < models.size()) {
            if (models.get(modelNumber).getIsComplex()) {
                ComplexModel c = (ComplexModel) models.get(modelNumber);
                for (int i = 0; i < c.getSize(); i++) {
                    if (c.getModel(i).getIsActive())
                        s += num + ",";
                    num++;
                }
                modelNumber++;
            } else {
                if (models.get(modelNumber).getIsActive())
                    s += num + ",";
                num++;
                modelNumber++;
            }
        }
        if (s.length() > 0)
            s = s.substring(0, s.length() - 1);
        return s;
    }