Question

I’m calling a web service which gets the data from the database and outputs the following JSON :

{"eventId":"1","eventTitle":"opening ceremony","eventCategory":"store","eventSubCategory":"clothing","eventDescription":"This is an event description of some kid for the first event","eventDate":"13/05/2012","eventTime":"14:52","eventAddress":"49 somerset road","eventCity":"southsea","eventCountry":"UK","eventWebsite":"www.nxtldn.com","eventEmail":"[e-mail]","eventPhone":"07757491567","eventKeywords":"clothes, street, wear, heart, love"},{"eventId":"2","eventTitle":"cupcakes","eventCategory":"Store","eventSubCategory":"food","eventDescription":"This is an event description of some kid for the second event","eventDate":"17/05/2012","eventTime":"11:22","eventAddress":"12 cleveleys road","eventCity":"london","eventCountry":"UK","eventWebsite":"www.ashshort.com","eventEmail":"[e-mail]","eventPhone":"0778514562","eventKeywords":"cupcakes, store, london, hipster"}]

which I append (I have tested to see if the JSON is valid using http://jsonlint.com/):

{"Events":[{"eventId":"1","eventTitle":"opening ceremony","eventCategory":"store","eventSubCategory":"clothing","eventDescription":"This is an event description of some kid for the first event","eventDate":"13/05/2012","eventTime":"14:52","eventAddress":"49 somerset road","eventCity":"southsea","eventCountry":"UK","eventWebsite":"www.nxtldn.com","eventEmail":"[e-mail]","eventPhone":"07757491567","eventKeywords":"clothes, street, wear, heart, love"},{"eventId":"2","eventTitle":"cupcakes","eventCategory":"Store","eventSubCategory":"food","eventDescription":"This is an event description of some kid for the second event","eventDate":"17/05/2012","eventTime":"11:22","eventAddress":"12 cleveleys road","eventCity":"london","eventCountry":"UK","eventWebsite":"www.ashshort.com","eventEmail":"[e-mail]","eventPhone":"0778514562","eventKeywords":"cupcakes, store, london, hipster"}]}

I’m calling it using an AsyncTask

public class EventSync extends AsyncTask<String, Integer, EventsList> {

EventsList elist1 = new EventsList();

@Override
protected EventsList doInBackground(String... urls) {
    String tempurl = urls[0];
    String output = "";
    InputStream is = null;
    StringBuilder sb = new StringBuilder();
    EventsList list = new EventsList();
    try
    {
        URL url = new URL(tempurl);
        HttpURLConnection con = (HttpURLConnection) url.openConnection();
        con.connect();
        is = con.getInputStream();

        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        String line = null;

        while((line = reader.readLine()) != null)
        {
            sb.append(line + "\n");
        }

    }
    catch (Exception e)
    {
        e.printStackTrace();
    }
    finally
    {
        try
        {
            is.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }

    output = sb.toString();
    String json = "{\"Events\":" + output + "}";
    System.out.println(json);
    Gson gson = new Gson();
// When debugging this is the line I believe it fails on, It points to a bit of memory but the list is empty.
    EventsList jsonlist = gson.fromJson(json, EventsList.class);

    return jsonlist;
}

@Override 
protected void onPostExecute(EventsList list)
{

    System.out.println("in on post");
    for (Event event : list.getEvents())
    {
        System.out.println(event.getEventId());
    }
}}

public class EventsList {

public EventsList(){

}

private List<Event> events;

public List<Event> getEvents()
{
    return events;
}

public void setEventsList(List<Event> events)
{
    this.events = events;
}}

public class Event {

private String eventId;
private String eventTitle;
private String eventCategory;
private String eventSubCategory;
private String eventDescription;
private String eventDate;
private String eventTime;
private String eventAddress;
private String eventCity;
private String eventCountry;
private String eventWebsite;
private String eventEmail;
private String eventPhone;
private String eventKeywords;

public Event()
{

}

// ALL GETS AND SETS

At the moment I’m just trying to test it to see if it will return before I use a custom adapter to populate a listview. But unfortunate I am getting the following error:

11-10 23:37:08.315: E/AndroidRuntime(5592): FATAL EXCEPTION: main
11-10 23:37:08.315: E/AndroidRuntime(5592): java.lang.NullPointerException
11-10 23:37:08.315: E/AndroidRuntime(5592):     at com.nxtldn.trill.EventSync.onPostExecute(EventSync.java:71)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at com.nxtldn.trill.EventSync.onPostExecute(EventSync.java:1)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at android.os.AsyncTask.finish(AsyncTask.java:631)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at android.os.AsyncTask.access$600(AsyncTask.java:177)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at android.os.Looper.loop(Looper.java:137)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at android.app.ActivityThread.main(ActivityThread.java:4745)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at java.lang.reflect.Method.invokeNative(Native Method)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at java.lang.reflect.Method.invoke(Method.java:511)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-10 23:37:08.315: E/AndroidRuntime(5592):     at dalvik.system.NativeStart.main(Native Method)

I new to android so I’m not sure if there is a better way of doing this or what the correct way is.

Is it down the the structure of my JSON why the GSON wont accept and returns null pointers?

Many thanks in advance to anyone that can help 🙂

Answer 1

I found it was due to me adding “/n” to my string builder, creating the new line and chopping off the final } of the json. Thanks everyone