Parsing JSON data in Java

Question

I want to parse the some data from this page: http://www.bbc.co.uk/radio1/programmes/schedules/england/2013/03/1.json

The data I want to parse is the titles however I am unsure how I can extract the data. This is what I have done so far:

 import java.io.BufferedReader;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.net.HttpURLConnection;
 import java.net.URL;
 import org.json.simple.JSONObject;
 import org.json.simple.parser.JSONParser;

 public class Test
 {
    public Test() { }

    public static void main(String[] args)
    {
            URL url;
            HttpURLConnection connection = null;
            InputStream is = null;
            JSONParser parser = new JSONParser();

            try
            {
                    url = new URL("http://www.bbc.co.uk/radio1/programmes/schedules/england/2013/03/1.json");
                    connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.connect();
                    is = connection.getInputStream();
                    BufferedReader theReader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
                    String reply;
                    while ((reply = theReader.readLine()) != null)
                    {
                            System.out.println(reply);
                            Object obj = parser.parse(reply);
                            JSONObject jsonObject = (JSONObject) obj;
                            String title = (String) jsonObject.get("time");
                            System.out.println(title);
                    }
            }
            catch (Exception e) {
                    e.printStackTrace();
            }
    }

}

This just returns null. Can anybody tell me what I need to change? Thanks.

Doesn't seem like there is a JSON object in your JSON with name time. — Sotirios Delimanolis
– Sotirios Delimanolis, Commented Nov 24, 2013 at 22:23
sorry that was an error on my part, time is meant to say title — user2104612
– user2104612, Commented Nov 24, 2013 at 22:37
You also assume that every line is a valid json object. I am unsure of how the results are returned from the server. But if the object is split out on many lines (which is valid json), your code will break — Oskar Kjellin
– Oskar Kjellin, Commented Nov 24, 2013 at 22:39
The JSON objects with name title are nested. You need to get every level above it (containing it) to retrieve it. — Sotirios Delimanolis
– Sotirios Delimanolis, Commented Nov 24, 2013 at 22:40

Sotirios Delimanolis · Accepted Answer · 2013-11-24 22:41:54Z

5

If you read the javadoc of JSONObject#get(String) which is actually HashMap.get(String), it states

Returns: the value to which the specified key is mapped, or null if this map contains no mapping for the key

Your JSON does not contain a mapping for the key time.

Edit:

If you meant title instead of time, take this extract of the JSON

{"schedule":{"service":{"type":"radio","key":"radio1","title":"BBC Radio 1",...

You need to first get schedule as a JSONObject, then service as a JSONObject, and then title as a normal String value. Apply this differently depending on the type of JSON value.

edited Nov 24, 2013 at 22:41

answered Nov 24, 2013 at 22:30

Sotirios Delimanolis

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Comments

Guy Gavriely · Accepted Answer · 2013-11-24 22:40:48Z

0

use something like JSONGen to better understand your data structures, maybe even map your data to the generated objects using google-gson library

answered Nov 24, 2013 at 22:40

Guy Gavriely

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2 Comments

Oskar Kjellin Over a year ago

Although this is helpful, it is not really an answer to his question

Guy Gavriely Over a year ago

it is clear that "time" field is not there, the question is what's there instead, I thought generating java objects will help him better understand what are the available fields

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