how to create json object with multiple array within it using org.json.JSONObject package in java?

Question

I want to create json object as, {"jsonName":[{"id":"1","name":"abc"},{"id":2,"name":"pqr"}]} "jsonName" fetch the data from database and I want to create the object from that data. and I want to update some value from that json object with "id" after we created that.

Suppose I run the query from java..

String selectStr = "select * from emp";
ResultSet rs = ps.executeQuery ();
while(rs.next())
{
.....
}

I'm fetching data like this and wants to create and json object that store all the data rows. can someone please help me .. I'm new to json object.

MTroy · Accepted Answer · 2017-05-11 00:17:19Z

1

Using org.json library:

JSONArray elements  = new JSONArray();
JSONObject rootJson = new JSONObject();
String selectStr    = "select * from emp";
try
{
    JSONArray elements  = null; // to prevent query returning empty resultset
    JSONArray el        = new JSONArray();

    ResultSet rs = ps.executeQuery();
    while(rs.next())
    {
        JSONObject el = new JSONObject();
        el.put("id", rs.getInt(1));
        el.put("name", rs.getString(2));
        elements.put(element);
    }

    rootJson.put("jsonName", elements);

}catch(Exception e)
{
    e.printStackTrace();
}

edited May 11, 2017 at 0:17

answered May 10, 2017 at 23:58

MTroy

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Comments

Abhilash · Accepted Answer · 2017-05-10 09:32:01Z

0

You can try quick-json. Which can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. quick-json can work with any arbitrary Java objects.

answered May 10, 2017 at 9:32

Abhilash

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Comments

nbokmans · Accepted Answer · 2017-05-10 10:35:11Z

0

When using a library such as gson (see: https://github.com/google/gson) doing this becomes a trivial task. You can simply define a structure in the shape of classes such as this:

public class JsonObj {
    public List<JsonItem> jsonName;
}

public class JsonItem {
    public int id;
    public String name;
}

Then, you can use gson to serialize your object into json (exhaustive example, but you get the point):

Gson gson = new Gson();
JsonObj obj = new JsonObj();
obj.jsonName = new ArrayList<String>();

String selectStr = "select * from emp";
ResultSet rs = ps.executeQuery();
while(rs.next())
{
    JsonItem item = new JsonItem();
    item.id = rs.getInt(1); //or whatever column index goes here
    item.name = rs.getString(2); //or whatever column index goes here
    obj.jsonName.Add(item);
}
String json = gson.toJson(obj);

json object will now contain the serialized json in String format.

edited May 10, 2017 at 10:35

answered May 10, 2017 at 9:32

nbokmans

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7 Comments

abc12345 Over a year ago

You are creating JsonItem two times, If we have data 100 times then? can we create this using loop? please tell me

nbokmans Over a year ago

Of course you can, you can make it as wild as you want. Althought at that point it's better to substitute the array for a list (both serialize to an array, but working with an arraylist is easier than creating an array of all the objects). I'll update my code in the post accordingly.

abc12345 Over a year ago

Thanks @nbokmans for your help. but if we are going to fetch the data from database for id,name then what will be the changes to do ? can you please give me some code.

nbokmans Over a year ago

Well that depends on how you fetch data from the database. That's a separate problem/piece of functionality. Can you update your question to show some example data from the database and how you fetch it?

abc12345 Over a year ago

hey I have updated my question can you please look it into that?

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