Convert from LinkedHashMap to Json String

Question

I'm Workin with Mongo using Jongo, when I do a query I receive a LinkedHashMap as result.

Iterator one = (Iterator) friends.find(query).projection("{_id:0}").as(Object.class);
while (one.hasNext()) {
 LinkedHashMap data = new LinkedHashMap();
 data = (LinkedHashMap) one.next();
 String content = data.toString();
}

the problem is that if the json is {"user":"something"} content will be {user=something}, it is not a json is only toString method from HashMap.

How I can get the original JSON?

I don't have a class to map the response and it isn't a solution create a map class, that is why I use a Object.class.

• Dancrumb: What is the type of datos?

Answer 1

If you have access to some JSON library, it seems like that's the way to go.

If using org.json library, use public JSONObject(java.util.Map map):

String jsonString = new JSONObject(data).toString()

If Gson, use the gson.toJson() method mentioned by @hellboy:

String jsonString = new Gson().toJson(data, Map.class);

• nommer: for JSONObject(), only works for a Map<String, String>! (stackoverflow.com/questions/12155800/…)
• pkanane: you can use String jsonString = new JSONObject(data).toJSONString() if that helps

Answer 2

You can use Gson library from Google to convert any object to JSON. Here is an example to convert LinkedHashMap to json -

Gson gson = new Gson();
String json = gson.toJson(map,LinkedHashMap.class);

Answer 3

One of the com.mongodb.BasicDBObject constructors takes a Map as input. Then you just have to call the toString() on the BasicDBObject object.

Iterator one = (Iterator) friends.find(query).projection("{_id:0}").as(Object.class);
 while (one.hasNext()) {
 LinkedHashMap data= new LinkedHashMap();
 data= (LinkedHashMap) one.next();
 com.mongodb.BasicDBObject bdo = new com.mongodb.BasicDBObject(data); 
 String json = bdo.toString();
 }

Answer 4

I resolved the problem using the following code:

 Iterator one = (Iterator) friends.find(query).projection("{_id:0}").as(Object.class);
 while (one.hasNext()) {
 Map data= new HashMap();
 data= (HashMap) one.next();
 JSONObject d = new JSONObject();
 d.putAll(data);
 String content=d.toString();
 }

Answer 5

if(data instanceof LinkedHashMap){
 json=new Gson.toJson(data,Map.class).toString();
}
else{
 json=data.toString();
}
return Document.parse(json);