Converting ArrayList to JSON - Android

Question

I have a Array List and a separate string. i want to convert these into JSON format and expect it below json format.

Expected format,

{ 
"last_sync_date": "2014-06-30 04:47:45",
"recordset": [
 {
 "contact_group": {
 "guid": "y37845y8y",
 "name": "Family", 
 "description": "Family members", 
 "isDeleted": 0 
 } 
 },
 {
 "contact_group": { 
 "guid": "gt45tergh4", 
 "name": "Office", 
 "description": "Office members", 
 "isDeleted": 0 
 } 
 } 
]
} 

i used this way bt it's wrong,

public void createGroupInServer(Activity activity, String lastSyncDateTime, ArrayList<ContactGroup> groups)
 throws JSONException {
 // create json object to contact group
 JSONObject syncDateTime = new JSONObject();
 syncDateTime.putOpt("last_sync_date", lastSyncDateTime);
 JSONArray jsArray = new JSONArray("recordset");
 for (int i=0; i < groups.size(); i++) {
 JSONObject adsJsonObject = new JSONObject("contact_group");
 adsJsonObject = jsArray.getJSONObject(i);
 adsJsonObject.put("guid", groups.get(i).getGroupId());
 adsJsonObject.put("name", groups.get(i).getGroupName());
 adsJsonObject.put("isDeleted", groups.get(i).getIsDeleted());
}

please help.

• Vincent Mimoun-Prat: Have you considered using Jackson or GSON to write less bugs? If not, you should. The above task will be simple.
• Stephen C: @ZhenxiaoHao - No. The Question is clearly about turning Java objects into JSON. The JSON he has supplied is clearly intended to be what the sample Java code generates.

Answer 1

You are mostly on the right track ... but there are a few mistakes:

public JSONObject createGroupInServer(
 Activity activity, String lastSyncDateTime,
 ArrayList<ContactGroup> groups)
 throws JSONException {
 JSONObject jResult = new JSONObject();
 jResult.putOpt("last_sync_date", lastSyncDateTime);
 JSONArray jArray = new JSONArray();
 for (int i = 0; i < groups.size(); i++) {
 JSONObject jGroup = new JSONObject();
 jGroup.put("guid", groups.get(i).getGroupId());
 jGroup.put("name", groups.get(i).getGroupName());
 jGroup.put("isDeleted", groups.get(i).getIsDeleted());
 // etcetera
 JSONObject jOuter = new JSONObject();
 jOuter.put("contact_group", jGroup);
 jArray.put(jOuter);
 }
 jResult.put("recordset", jArray);
 return jResult;
}

But I agree with the other Answers that suggest you use a "mapping" technology like GSON rather than coding this by hand. Especially if this gets more complicated.

Answer 2

parse to JSONArray?

JSONArray jsonArray = (JSONArray)new JSONParser().parse(your json string);

For your code

 JSONObject jsonObject = (JSONObject)new JSONParser().parse(your json string);
 JSONArray array = (JSONArray)jsonObject.get("recordset"); 

Answer 3

You could use GSON.

It provides a lot of functionality and its very simple to use.

Have a look at these examples.

http://kylewbanks.com/blog/Tutorial-Android-Parsing-JSON-with-GSON

http://www.techrepublic.com/blog/software-engineer/use-gson-to-work-with-json-in-your-android-apps/

Hope this helps.