Nsryjdtyk

I am creating a Json format for my nav bar menu and menu items.. i have put some effort and have done some work for one loop but what i want is to be nested json

My database has Data like This

What i want is to create a Json format from this table like this

        var data = {

"India":

    [

        {  "Submenu": "delhi", "link" : "https://www.google.com" },

        {  "Submenu": "mumbai", "link" : "https://www.google.com" }

    ],

"USA":

    [

        {  "Submenu": "NY", "link" : "https://www.google.com" },

        {  "Submenu": "california", "link" : "https://www.google.com" }

    ],

    "England":

        [

            {  "Submenu": "London", "link" : "https://www.google.com" },

            {  "Submenu": "Menchester", "link" : "https://www.google.com" }

        ],



"logout":

    

};

Till now i have tried this

 LinkedHashMap<Object, Object> lhm = null;

        List<Map<Object, Object>> list = new ArrayList<Map<Object, Object>>();







        String sql="select menu,submenu and link from table_name";





        String name,link;

        String str = null;

        Gson gson = new Gson();



        try {



            resultSet = statement.executeQuery(sql);

            while(resultSet.next()){

            lhm=    new LinkedHashMap<Object, Object>();

            name=   resultSet.getString("submenu"); 

            link=   resultSet.getString("link");

            lhm.put("submenu", name);

            lhm.put("link", link);



            list.add(lhm);  

            str = gson.toJson(list);

            }

            System.out.println(str);

from this i am getting result like this

[{"submenu":"Delhi","link":"https://www.google.com"},{"submenu":"mumbai","link":"https://www.google.com"},{"submenu":"NY","link":"https://www.google.com"},{"submenu":"California","link":"https://www.google.com"},{"submenu":"London","link":"https://www.google.com"},{"submenu":"Mencherter","link":"https://www.google.com"}]

now i have got the sub menus and there link .. i am facing trouble on linking the submenus to there respective menus .. i am facing issue in looping the data acc to my requirement if anyone of you have any suggestion and idea please help me out

First retrieve required dat from DB:

select menu, sub-menu, link from table_name;

Then create a Map to hold a menu content:

Map<String, List<Map<String, String>> map = new LinkedHashMap<>();

Then read result sets and fill a map, using menu name as a key:

while(rs.next()) {

    map.compute(rs.getString("menu"), (menu, subMenus) -> {

        Map<String, String> mapSubMenu = new LinkedHashMap<>();

        mapSubMenu.put("Submenu", rs.getString("sub-menu"));

        mapSubMenu.put("link", rs.getString("link"));



        subMenus = subMenus != null ? subMenus : new ArrayList<>();

        subMenus.add(mapSubMenu);



        return subMenus;

    });

}

Try Using Map<String,List<Map<Object, Object>>> instead of List<Map<Object, Object>> so that you can give menu name to your main menu.

LinkedHashMap<Object, Object> lhm; //initiaze

Map<String,List<Map<Object, Object>>> map;

List<Map<Object, Object>> list;

while(rs.next())

{

    String menu = rs.getString("menu");

    String subMenu = rs.getString("sub-menu");

    String link = rs.getString("link");

        lhm.put("submenu", name);

        lhm.put("link", link);



       if (map.containsKey(menu))  //check if mainmenu already present

       {

         map.get(menu).add(lhm);  

       }

       else

        { 

         //initialize list here

         list.add(lhm);

         map.put(menu,list); 

        }



}

str = gson.toJson(list);  

Follow idea only and customize code as your need