Converting array list object to jsonarray

Question

I have arraylist that needs to be converted to json array to post in the server

the format of json should be like this:

{
   p:1,
   s:["a":1,"b":2],["a":2,"b":3],["a":3,"b":4]
}

Let say I have:

List<MyObject> objectList = new ArrayList<MyObject>();
MyObject myObject = new MyObject();
myObject .setA(1);
myObject .setB(2);

myObject .setA(2);
myObject .setB(3);

myObject .setA(3);
myObject .setB(4);

objectList.add(myObject);

My current code is:

   for (int i = 0; i < objectList.size(); i++) {
        JSONArray ar = new JSONArray();
        ar.put("a:"+objectList.get(i).getA());
        ar.put("b:"+objectList.get(i).getB());

        jOuter.put("s",ar);
    }

but this doesnt work, the current return is:

{"p":1,"s":["a:20","b:10.0"]}

Thanks.

That json you show is far from valid. Keys must be strings, values can be lists [ ], but lists cannot contain key value pairs, those go in objects { } — Tim
– Tim, Commented Sep 29, 2015 at 8:47
you are putting to your JSONArray a String, while you should put JSONObject — user902383
– user902383, Commented Sep 29, 2015 at 8:58
how about putting it in a hashmap then add it to json? i just need the json format above. — Cris
– Cris, Commented Sep 29, 2015 at 9:01
do you think {"p":1, "s"[{"a":1,"b":2},{"a":2,"b":3}] are valid and the same that i need? — Cris
– Cris, Commented Sep 29, 2015 at 9:03

Prexx · Accepted Answer · 2015-09-29 09:18:44Z

2

Shouldn't it be something like this?

JSONArray ar = new JSONArray();
for (int i = 0; i < objectList.size(); i++) {

        JSONObject objects = new JSONObject();
        objects.put("a", objectlist.get(i).getA();
        objects.put("b", objectlist.get(i).getB();

        ar.put(objects);

    }
        jOuter.put("s",ar);

edited Sep 29, 2015 at 9:18

answered Sep 29, 2015 at 8:49

Prexx

2,9795 gold badges33 silver badges49 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Cris Over a year ago

return is {"p":1,"s":[{"a":1,"b":2},{}]}

Prexx Over a year ago

Someone already did it: the JSON array has to be outside the for loop

kyleruss · Accepted Answer · 2015-09-29 09:20:23Z

2

Your s entry is actually a JsonArray, while your p is just a property. Here I am using Gson but you could easily apply it to whichever library you are using. So you can do the following:

JsonObject jObj = new JsonObject();
jObj.addProperty("p", 1);

JsonArray sArr  = new JsonArray();

 for (int i = 0; i < objectList.size(); i++)
 {
        JsonObject innerObj = new JsonObject();
        innerObj.addProperty("a:"+objectList.get(i).getA());
        innerObj.addProperty("b:"+objectList.get(i).getB());

        sArr.add(innerObj);
 }

 jObj.addProperty("s", sArr);

The output is:

{
  "p":1,
  "s":[{"a":1,"b":2},{"a":3,"b":4}]
}

answered Sep 29, 2015 at 9:20

kyleruss

4973 silver badges9 bronze badges

Comments

Kunu · Accepted Answer · 2015-09-29 09:08:43Z

1

Your required format is invalid. I think you are looking for something like this

{
  "p": 1,
  "s": [
    {
      "a": 1,
      "b": 2
    },
    {
      "a": 2,
      "b": 3
    },
    {
      "a": 3,
      "b": 4
    }
  ]
}

For this code will be like as below

JSONArray jArray = new JSONArray();
for (int i = 0; i < objectList.size(); i++) {
        JSONObject job= new JSONObject();
        job.put("a",objectList.get(i).getA());
        job.put("b",objectList.get(i).getB());

        jArray .put(job);
}

try {
        jOuter.put("s", jArray );
} catch (JSONException e) {
        e.printStackTrace();
}

answered Sep 29, 2015 at 9:08

Kunu

5,1826 gold badges35 silver badges65 bronze badges

Comments

Diksha Dhiman · Accepted Answer · 2015-09-29 09:17:58Z

Please check following code: This will make the proper formatting:

JSONObject jo = new JSONObject();
    try {
        jo.put("p", "1");

        JSONArray jarr = new JSONArray();
        for (MyObject listItem : objectList) {
            JSONObject inner = new JSONObject();
            inner.put("a", listItem.getA());
            inner.put("b", listItem.getB());

            jarr.put(inner);
        }
        jo.put("s", jarr);
    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

It will return output like:

{
  "p":1,
  "s":[{"a":1,"b":2},{"a":2,"b":3},{"a":3,"b":4}]
}

This makes a proper json, which I think you need! Do let me know, if I am wrong somewhere.

Collectives™ on Stack Overflow

Converting array list object to jsonarray

4 Answers 4

2 Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related