如何在Servlet中发布Json数据？

Question

I have a json data which can be something like:

1st json data   
[
  {
    "id_form_delegate": "1",
    "nama_merchant": "MATAHARI BARU SERASI",
    "kota_merchant": "BALI",
    "alamat_merchant": "JL PAKUBUWONO 2D",
    "province_merchant": "BALI",
    "mid_merchant": [
      "112000902755",
      "112000902754"
    ],
    "tid_merchant": [
      "2431002547",
      "2531016215"
    ]
  }
]

or something like

2nd json data
[
  {
    "id_form_delegate": "1",
    "nama_merchant": "MATAHARI BARU SERASI",
    "kota_merchant": "BALI",
    "alamat_merchant": "JL PAKUBUWONO 2D",
    "province_merchant": "BALI",
    "mid_merchant": "112000902755",
    "tid_merchant": "2431002547"
  }
]

This my servlet code

JSONArray arrMid = jsonObject.getJSONArray("mid_merchant");
 mid = new String[arrMid.size()];
 JSONArray arrTid = jsonObject.getJSONArray("tid_merchant");
 tid = new String[arrTid.size()];

//            
                System.out.println("nama_merchant: " + nama_merchant);
                System.out.println("kota_merchant: " + kota_merchant);
                System.out.println("alamat_merchant: " + alamat_merchant);
                System.out.println("province_merchant: " + province_merchant);
                System.out.println("mid: " + mid.length);
                System.out.println("tid: " + tid.length);

if post 1st data result success, but if I post 2nd data I've Got error

this my error logs

net.sf.json.JSONException: JSONObject["mid_merchant"] is not a JSONArray. net.sf.json.JSONException: JSONObject["tid_merchant"] is not a JSONArray.

how to get value mid_merchant.length & tid_merchant.length using JSONArray

Thanks

Answer 1

The problem is that mid_merchant isn't an array in the second case, so you can't use JSONArray to get it's length because it has no length, it's just a String. You could send an array with only one value:

"mid_merchant": ["112000902755"],

or, if that's not what you want, you can check if it is an array (or even capture that exception) and get the String value with the getString method if it's not an array:

String stringMid = jsonObject.getString("mid_merchant");

Answer 2

You can use method get(String field) and check type of result:

Object node = jsonObject.get("mid_merchant");

String[] mid;
if (node instanceof JSONArray) {
   mid = new String[((JSONArray) node).size()];
} else {
   mid = new String[1];
}

or one-liner:

String[] mid = new String[node instanceof JSONArray ? ((JSONArray) node).size() : 1];

Answer 3

Try the following code

JSONArray arrMid=json.getJSONArray("mid_merchant");
String mid=arrMid.getJSONOBJECT.getJSONObject(0).getString("mid_merchant");

JSONArray tidMid=json.getJSONArray("tid_merchant");
String mid=tidMid.getJSONOBJECT.getJSONObject(0).getString("tid_merchant");