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.

Answer 1

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.

Answer 2

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.

Answer 3

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();
}