How to parse JSON object into `Map<String, HashSet<String>>`

Question

I'd like to parse this JSON object:

"{
  \"Rao\":[\"Q7293658\",\"\",\"Q7293657\",\"Q12953055\",\"Q3531237\",\"Q4178159\",\"Q1138810\",\"Q579515\",\"Q3365064\",\"Q7293664\",\"Q1133815\"],
  \"Hani Durzy\":[\"\"],
  \"Louise\":[\"\",\"Q1660645\",\"Q130413\",\"Q3215140\",\"Q152779\",\"Q233203\",\"Q7871343\",\"Q232402\",\"Q82547\",\"Q286488\",\"Q156723\",\"Q3263649\",\"Q456386\",\"Q233192\",\"Q14714149\",\"Q12125864\",\"Q57669\",\"Q168667\",\"Q141410\",\"Q166028\"],
  \"Reyna\":[\"Q7573462\",\"Q2892895\",\"Q363257\",\"Q151944\",\"Q3740321\",\"Q2857439\",\"Q1453358\",\"Q7319529\",\"Q733716\",\"Q16151941\",\"Q7159448\",\"Q5484172\",\"Q6074271\",\"Q1753185\",\"Q7319532\",\"Q5171205\",\"Q3183869\",\"Q1818527\",\"Q251862\",\"Q3840414\",\"Q5271282\",\"Q5606181\"]
}"

and with that data generate a Map<String, HashSet<String>>.

Essentially I want to reverse this procedure.

All the code for this project can be found on my github page here, it's quite short.

---

update

        File f = new File("/home/matthias/Workbench/SUTD/nytimes_corpus/wdtk-parent/wdtk-examples/JSON_Output/user.json");

        String jsonTxt = null;

        if (f.exists())
        {
            InputStream is = new FileInputStream("/home/matthias/Workbench/SUTD/nytimes_corpus/wdtk-parent/wdtk-examples/JSON_Output/user.json");
            jsonTxt = IOUtils.toString(is);


        }
        //System.out.println(jsonTxt);


        Gson gson=new Gson(); 


        Map<String, HashSet<String>> map = new HashMap<String, HashSet<String>>();
        map=(Map<String, HashSet<String>>) gson.fromJson(jsonTxt, map.getClass());

        //// \\ // ! PRINT IT ! // \\ // \\ // \\ // \\ // \\ // \\
       for (Map.Entry<String, HashSet<String>> entry : map.entrySet()) 
       {
           System.out.println(entry.getKey()+" : " + Arrays.deepToString(map.entrySet().toArray()) );
       }

Answer 1

Using Gson

Gson gson = new Gson(); 
String json = "<YOUR_JSON_STRING_HERE>";
Map<String, HashSet<String>> map = new HashMap<String, HashSet<String>>();
map = (Map<String, HashSet<String>>) gson.fromJson(json, map.getClass());

---

Update:

Use TypeToken

Type type = new TypeToken<Map<String, HashSet<String>>>(){}.getType();
map = (Map<String, HashSet<String>>) gson.fromJson(json, type);

---

Or you could parse it...

• Create an object of JSONObject
• Create an object of HashMap
• Iterate over jsonObj.keys() and for every key get value like jsonObj.getString(key).
• Put it in the map like map.put(key, value).