Convert Json array "[{}]" to "[]" in Java

Question

I want to convert my Blank Json array to the Null Json array.

For ex., My Json array is like "[{}]" and if I got this array then automatically converts to "[]".

My code is like as below :

JsonObject jo = FetchData.getAllItemsAvg(request.getParameter("where"), request.getParameter("lastNum"),request.getParameter("limitAvgNum"));
JsonArray ja = new JsonArray();
ja.add(jo); // Some times ja like "[{}]" .

It's not an empty array, it is an array containing a single object with no properties. — Boris the Spider
– Boris the Spider, Commented Apr 12, 2016 at 12:35
Proper answer depends on what is your input (is it string or instance of some kind of JSONArray class) and what JSON library you are using. If it is string then maybe simply replace each {} with empty string. — Pshemo
– Pshemo, Commented Apr 12, 2016 at 12:58
Hi, My code is like : JsonArray ja = new JsonArray(); ja.add(jo); ja.toString().replace("{}", ""); jo = Json Object. I have tried with this but still not working. Thank you. — yogesh jalodara
– yogesh jalodara, Commented Apr 12, 2016 at 13:02

marthursson · Accepted Answer · 2016-04-12 13:23:05Z

2

Check if the object is empty before adding it to the array. (assuming you're using JsonObject):

JsonObject jo = FetchData.getAllItemsAvg(
                          request.getParameter("where"),
                          request.getParameter("lastNum"),
                          request.getParameter("limitAvgNum"));
JsonArray ja = new JsonArray();
if(!jo.isEmpty()){
    ja.add(jo);
}

For com.google.gson.JsonObject:

JsonObject jo = FetchData.getAllItemsAvg(
                          request.getParameter("where"),
                          request.getParameter("lastNum"),
                          request.getParameter("limitAvgNum"));
JsonArray ja = new JsonArray();
if(!jo.entrySet().isEmpty()){
    ja.add(jo);
}

edited Apr 12, 2016 at 13:23

answered Apr 12, 2016 at 13:11

marthursson

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4 Comments

yogesh jalodara Over a year ago

Can you tell me how to check? Because I have tried with following but i'm fail : stackoverflow.com/questions/19170338/… stackoverflow.com/questions/12585492/… And so on..

yogesh jalodara Over a year ago

Yea, i have already tried with this but i'm getting "The method isEmpty() is undefined for the type JsonObject" error.

marthursson Over a year ago

Which JsonObject are you using (link to API preferred)?

yogesh jalodara Over a year ago

Yea got my answer. Thank you for helping me. I have use "jo.entrySet().size() > 0" instead of "!jo.isEmpty()"

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