Bewaaaaare of Gson! It's very cool, very great, but the second you want to do anything other than simple objects, you could easily need to start building your own serializers (which isn't that hard).

Also, if you have an array of Objects, and you deserialize some json into that array of Objects, the true types are LOST! The full objects won't even be copied! Use XStream.. Which, if using the jsondriver and setting the proper settings, will encode ugly types into the actual json, so that you don't loose anything. A small price to pay (ugly json) for true serialization.

Note that Jackson fixes these issues, and is faster than GSON.

Extending the answer added by @Deepak. Both approaches are feasible but I preferred Gson as I was already using it.

Using JSONObject

JSONObject jsonObject = new JSONObject(input);  


Set<String> keys =jsonObject.keySet();
for(String key:keys) {
    System.out.println("Key :: "+key +", Value :: "+jsonObject.get(key));;
}

Using Gson

public static void main(String[] args) {
        
    String json = "{\"Sample_01\":{\"class\":\"Tenant\",\"A1\":{\"class\":\"Application\",\"template\":\"http\",\"serviceMain\":{\"class\":\"Service_HTTP\",\"virtualAddresses\":[\"10.0.1.10\"],\"pool\":\"web_poolddd\"},\"web_poolddd\":{\"class\":\"Pool\",\"monitors\":[\"http\"],\"members\":[{\"servicePort\":80,\"serverAddresses\":[\"192.0.13.10\",\"192.0.14.11\"]}]}}},\"Sample_20\":{\"class\":\"Tenant\",\"A1\":{\"class\":\"Application\",\"template\":\"http\",\"serviceMain\":{\"class\":\"Service_HTTP\",\"virtualAddresses\":[\"10.2.2.2\"],\"pool\":\"web_pool_data\"},\"web_pool_data\":{\"class\":\"Pool\",\"monitors\":[\"http\"],\"members\":[{\"servicePort\":80,\"serverAddresses\":[\"192.0.10.10\",\"192.0.10.11\"]}]}}}}";
    
    Type listType = new TypeToken<Map<String, Object>>(){}.getType();
    Gson gson = new Gson();
    Map<String,Object> myList = gson.fromJson(json, listType);

    JsonParser parser = new JsonParser();

    for (Map.Entry<String,Object> m : myList.entrySet())
    {
        System.out.println("==============");
        if(m.getValue() instanceof String){
            // get String value
        }else{ // if value is an Object
            
            System.out.println("VIP Sec: Name: "+m.getKey());
            Map<String,Object> myList1 = gson.fromJson(m.getValue().toString(), listType);
            for (Map.Entry<String,Object> m1 : myList1.entrySet())
            {
                if(!( m1.getValue() instanceof String)){
                    Map<String,Object> myList2 = gson.fromJson(m1.getValue().toString(), listType);
                    for (Map.Entry<String,Object> m2 : myList2.entrySet())
                    {
                         if(!( m2.getValue() instanceof String)){
                            Map<String,Object> myList3 = gson.fromJson(m2.getValue().toString(), listType);
                            for (Map.Entry<String,Object> m3 : myList3.entrySet())
                            {
                                if(m3.getKey().equals("virtualAddresses")){
                                    System.out.println("VIP Sec: IP Address: "+m3.getValue());
                                }
                                else if(m3.getKey().equals("pool")){
                                    System.out.println("Pool Sec: Name: "+m3.getValue());
                                }else if(m3.getKey().equals("monitors")){
                                    JsonArray monitors = parser.parse(m3.getValue().toString()).getAsJsonArray();
                                    int count = 0;
                                    while(count < monitors.size()){
                                        String monitor = monitors.get(count).getAsString();
                                        System.out.println("Monitor: "+monitor);
                                        count++;
                                    }
                                }else if(m3.getKey().equals("members")){
                                    JsonArray members = parser.parse(m3.getValue().toString()).getAsJsonArray();
                                    int count = 0;
                                    while(count < members.size()){
                                        // Parsing as Object to key values by key directly
                                        JsonObject mem = members.get(count).getAsJsonObject();
                                        String port = mem.get("servicePort").getAsString();
                                        System.out.println("Port: "+port);
                                        JsonElement ipAddrs = mem.get("serverAddresses");
                                        if(ipAddrs.isJsonArray()){
                                            JsonArray ips = ipAddrs.getAsJsonArray();
                                            int c = 0;
                                            while(c < ips.size()){
                                                String ip = ips.get(c).getAsString();
                                                System.out.println("IP: "+ip);
                                                c++;
                                            }
                                        }
                                        count++;
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}



OUTPUT:

==============
VIP Sec: Name: Sample_01
VIP Sec: IP Address: [10.0.1.10]
Pool Sec: Name: web_poolddd
Monitor: http
Port: 80.0
IP: 192.0.13.10
IP: 192.0.14.11
==============
VIP Sec: Name: Sample_20
VIP Sec: IP Address: [10.2.2.2]
Pool Sec: Name: web_pool_data
Monitor: http
Port: 80.0
IP: 192.0.10.10
IP: 192.0.10.11

Read more about 2nd approach here

We would need your class structure for more details.

As far as I am aware, I think you will need to have some mappings defined somewhere (I used xml's) and then try to match json with one of the mappings to create objects.

Google gson is good. I did it in Jackson

Also, converting objects should be trivial. But since you might have variable fields like tech11 and tech12 , you might want to store the "network" value as a string and then extract fields out of it when required.

Hope I could help.

Edit : Sotirious nails it.

What about this approach:

Class dataPair {
 private HashMap<String, String> dt= new HashMap<String, String>();
}

Check out Google's Gson: http://code.google.com/p/google-gson/

From their website:

Gson gson = new Gson(); // Or use new GsonBuilder().create();
MyType target2 = gson.fromJson(json, MyType.class); // deserializes json into target2

You would just need to make a MyType class (renamed, of course) with all the fields in the json string. It might get a little more complicated when you're doing the arrays, if you prefer to do all of the parsing manually (also pretty easy) check out http://www.json.org/ and download the Java source for the Json parser objects.

Converting the JSONObject to Map and setting the map to the pojo field, solved the issue and didn't lead me to writing a custom deserializer.

Map<Long, Double> resultData = objectMapper.readValue(resultData.getJSONObject("result").toString(), Map.class);
FinalResultData finaResultData = new FinalResultData(resultData);