java - Parse JSON file using GSON -

i want parse json file in java using gson :

{     "descriptor" : {         "app1" : {             "name" : "mehdi",             "age" : 21,             "messages": ["msg 1","msg 2","msg 3"]         },         "app2" : {             "name" : "mkyong",             "age" : 29,             "messages": ["msg 11","msg 22","msg 33"]         },         "app3" : {             "name" : "amine",             "age" : 23,             "messages": ["msg 111","msg 222","msg 333"]         }     } } 

but don't know how acceed root element : descriptor, after app3 element , name element.

i followed tutorial http://www.mkyong.com/java/gson-streaming-to-read-and-write-json/, doesn't show case of having root , childs elements.

imo, best way parse json response gson creating classes "match" response , use gson.fromjson() method.
example:

class response {     map<string, app> descriptor;     // standard getters & setters... }  class app {   string name;   int age;   string[] messages;   // standard getters & setters... } 

then use:

gson gson = new gson(); response response = gson.fromjson(yourjson, response.class); 

where yourjson can string, reader, jsonreader or jsonelement.

finally, if want access particular field, have do:

string name = response.getdescriptor().get("app3").getname(); 

you can parse json manually suggested in other answers, think approach clearer, more maintainable in long term , fits better whole idea of json.