JSON is a handy format while dealing with data in front end. However, we can't directly obtain JSON array if we are using Java querying data from database via JDBC. The default return type of querying data via JDBC is ResultSet.

Fortunately, below is an approach I found to convert SQL ResultSet to JSON array.

 
Remember to import.

import org.json.JSONArray;
import org.json.JSONObject;
import java.sql.ResultSet;

The convert method.

public static JSONArray convert(ResultSet resultSet) throws Exception {

	JSONArray jsonArray = new JSONArray();

	while (resultSet.next()) {

		int columns = resultSet.getMetaData().getColumnCount();
		JSONObject obj = new JSONObject();

		for (int i = 0; i < columns; i++)
			obj.put(resultSet.getMetaData().getColumnLabel(i + 1).toLowerCase(), resultSet.getObject(i + 1));

		jsonArray.put(obj);
	}
	return jsonArray;
}

where I found the code