How to construct a JSON from this Map data

Question

I have a Map with a key and value as linked List as shown below

{Ice creams=[Cone,KoolCool(21), Stick,KoolCool(25)]}

With this i need to construct a following json

{
    "name": "Ice creams",
    "T2": [
        {
            "name": "Cone",
            "T3": [
                {
                    "name": "KoolCool",
                    "leaf": []
                }
            ]
        },
        {
            "name": "Stick",
            "T3": [
                {
                    "name": "KoolCool",
                    "leaf": []
                }
            ]
        }
    ]
}

Every comma seperated value will increment the T value

I am trying to apprach this with the below

1. For every key in the Map Access its value as LinkedList
2. From that LinkedList access split it and construct the json

Could anybody please let me know if there is a better way of doing this ??

package com.util;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.Map;
public class Test {
    public static void main(String args[]) {
        Map<String, LinkedList<String>> consilatedMapMap = new LinkedHashMap<String, LinkedList<String>>();
        LinkedList<String> values = new LinkedList<String>();
        values.add("Cone,KoolCool(21)");
        values.add("Stick,KoolCool(25)");
        consilatedMapMap.put("Ice creams", values);

        /*
         * for (Map.Entry<String, LinkedList<String>> consilMap :
         * consilatedMapMap.entrySet()) {
         * 
         * String t1Category = consilMap.getKey(); LinkedList<String>
         * consiladatedList = consilMap.getValue();
         * 
         * 
         * for(int i=0;i<consiladatedList.size();i++) { String result =
         * consiladatedList.get(i);
         * 
         * String spliter[] = result.split(",");
         * 
         * for(int j=0;j<spliter.length;j++) { System.out.println(spliter[j]); }
         * 
         * }
         * 
         * }
         */


    }

}

Answer 1

I believe you're overcomplicating this - autoincremented names... The JSON structure doesn't match the Java structure... JSON generated partly by object structure, partly by parsing strings within it... even though you say "Every comma seperated value will increment the T value" this is obviously not true from the example.

Nevertheless... this is possible - even just using org.json (not sure why people keep suggesting GSON as a fix all to this...)

The primary idea here is to make a method for each part you need to generate, and pass the "level" around to generate the appropriate "Tn" property when you need it.

public class Test {

    private static JSONObject processString(String data, int level) throws JSONException {
        JSONObject json = new JSONObject();
        int index = data.indexOf(',');
        String name = data;
        String remainder = "";
        if (index < 0) {
            index = name.indexOf('(');
            if (index > 0) {
                name = data.substring(0, index);
            }
        } else {
            name = data.substring(0, index);
            remainder = data.substring(name.length() + 1);
        }
        json.put("name", name);

        JSONArray a = new JSONArray();
        if (remainder.length() > 0) {
            a.put(processString(remainder, level + 1));
            json.put("T" + level, a);
        } else {
            json.put("leaf", a);
        }
        return json;
    }  

    private static JSONArray processList(List<String> list, int level) throws JSONException {
        JSONArray json = new JSONArray();
        for (String data : list) {
            json.put(processString(data, level));
        }
        return json;
    }  

    private static JSONObject processMap(Map<String>, List<String>> map, int level) throws JSONException {
        JSONObject json = new JSONObject();
        for (String key : map.keySet()) {
            json.put("name", key);
            json.put("T" + level, processList(map.get(key), level + 1));
        }
        return json;
    }        

    public static void main(String args[]) {
        Map<String, List<String>> consilatedMapMap = new LinkedHashMap<String, List<String>>();
        List<String> values = new LinkedList<String>();
        values.add("Cone,KoolCool(21)");
        values.add("Stick,KoolCool(25)");
        consilatedMapMap.put("Ice creams", values);

        try {
            int level = 2;
            JSONObject json = processMap(consilatedMapMap, level);
        } catch(JSONException x) {
            x.printStackTrace();
            System.exit(-1);
        }
}

Answer 2

There is a utility library called Gson on Google code.You can check it out here

For some simple examples visit this

Answer 3

Look at folowing code:

     Map<String, LinkedList<String>> consilatedMapMap = new LinkedHashMap<String, LinkedList<String>>();
     LinkedList<String> values = new LinkedList<String>();
     values.add("Cone,KoolCool(21)");
     values.add("Stick,KoolCool(25)");
     consilatedMapMap.put("Ice creams", values);

     Gson gson=new Gson();
     String jsonElement=gson.toJson(consilatedMapMap);
    System.out.println(jsonElement);

Output

{"Ice creams":["Cone,KoolCool(21)","Stick,KoolCool(25)"]}

As you can see from the code and it's output, Gson library would convert your data structure to a json string.

All you need is this Gson library.