Question: I built a Map and serialized it into a JSON object, my code below:

```
Map<String,List<String>> mapTypeSubType= new Map<String,List<String>>();
if(actionPlanB2C.size()>0){
            for(OCTO_Action_Plan__c pl:actionPlanB2C){
               if(!mapTypeSubType.containskey(pl.OCTO_Type_Label__c)){
                    mapTypeSubType.put(pl.OCTO_Type_Label__c,new List<String> {pl.OCTO_Type_SubLabel__c});
               }else{
                    mapTypeSubType.get(pl.OCTO_Type_Label__c).add(pl.OCTO_Type_SubLabel__c);
               }
            }

        }
System.debug(mapTypeSubType);
String jsonMap=JSON.serialize(mapTypeSubType);
System.debug(jsonMap);

```

This code create the JSON : `{"TEST":["TEST"]}`

but I need the JSON object have the form: `{"type":"TEST","subtypes":["TEST"]}`. How can I serialize a map into a specific JSON object?

Answer: 
Here how you can achieve it.

```
map<string, object> mapToSerialize = new map<string, object>();
mapToSerialize.put('type', 'TEST');
//add you subtype like this
mapToSerialize.put('subtypes', new list<string>{'TEST'});
string jsonstring = JSON.serialize(mapToSerialize);

```
May be the following sample code helps:

```
Map<Object,List<Object>> mapTypeSubType= new Map<Object,List<Object>>();
for(Integer i=0; i<3; i++){
    if(!mapTypeSubType.containskey('"type":"TEST"')){
        mapTypeSubType.put('"type":"TEST"',new List<Object> {'"subtypes":"TEST"'});
    }else{
        mapTypeSubType.get('"type":"TEST"').add('TEST');
    }
}

System.debug(mapTypeSubType);
String jsonMap=JSON.serialize(mapTypeSubType);
System.debug(jsonMap);

//Here's the debug response:
{"\"type\":\"TEST\"":["\"subtypes\":\"TEST\"","TEST","TEST"]}

```