using Gee;
class Sas : GLib.Object {
    public int a {set;get;}
    //  public ArrayList<int> arr {set;get;}
    public Sas(int a) {
        this.a = a;
    }
}

string serialize_ArrayList(Value val){
    if (val.type ().is_a (typeof (Gee.ArrayList))) {
        unowned Gee.ArrayList<GLib.Object> arraylist_value = val as Gee.ArrayList<GLib.Object>;

        if (arraylist_value != null) {
            var array = new Json.Array.sized (arraylist_value.size);

            foreach (var item in arraylist_value) {
                //message(@"$(Json.gobject_serialize (item))");
                array.add_element (Json.gobject_serialize (item));
            }

            var node = new Json.Node (Json.NodeType.ARRAY);
            node.set_array (array);
            return node.get_string();
        }
        else return "Error";
    }
    else return "Error";
}

public static int main(string[] args) {
    var arrlist = new ArrayList<Sas>.wrap({new Sas(1),new Sas(2),new Sas(4)});
    foreach (var item in arrlist) {
        message(@"$(item.a)\n");
    }
    Value arristVal = Value(typeof(ArrayList<Sas>));
    arristVal = arrlist;
    string strResult = serialize_ArrayList(arristVal);
    message(strResult);
    return 0;
}