Question

In a Java Class, I have three List as fields in a class.
So I believe I made them available to the whole class? and all inner classes?

However, this does not work:
(For the example, I will only show one list here, not all three)

class Items extends ListActivity {

List<String> items = null;  // field

Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

            // stuff

    items = new ArrayList<String>();

    new Task().execute();

    Log.d("Size", String.valueOf(items.size()));



 }

 class Task extends AsyncTask<String, String, Void> {

    // in this subclass, I parse items from JSON and add to List "items".

     items = add(item);

 }

Once I exit the task, I seem to lose the items in the List. It Logs “size 0”; if I do it inside the task, it shows the proper amount of items. Am I missing a very basic point about the scope of List variables here?

EDIT: Below is the complete Task class (slightly cleaned up for posting)

class Task extends AsyncTask<String, String, Void> {
    private InputStream is = null;
    private String result = "";


    @Override
    protected Void doInBackground(String... params) {
        String url_select = "items.php";

        param = new ArrayList<NameValuePair>();
        param.add(new BasicNameValuePair("category", Category));

        HttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url_select);

        try {
            httpPost.setEntity(new UrlEncodedFormEntity(param));

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();

            // read content
            is = httpEntity.getContent();

        } catch (Exception e) {

            Log.e("log_tag", "Error in http connection " + e.toString());
        }
        try {
            BufferedReader br = new BufferedReader(
                    new InputStreamReader(is));
            StringBuilder sb = new StringBuilder();
            String line = "";
            while ((line = br.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            result = sb.toString();

        } catch (Exception e) {
            // TODO: handle exception
            Log.e("log_tag", "Error converting result " + e.toString());
        }

        return null;

    }

    protected void onPostExecute(Void v) {

        try {

            JSONArray jArray = new JSONArray(result);
            JSONObject json_data = null;
            for (int i = 0; i < jArray.length(); i++) {
                json_data = jArray.getJSONObject(i);
                item = json_data.getString("item");

                items.add(item);

                Log.d("Items", item);
            }
        } catch (JSONException e1) {
            Toast.makeText(getBaseContext(), "No items!",
                    Toast.LENGTH_SHORT).show();
        } catch (ParseException e1) {
            e1.printStackTrace();
        }


    }
}

Answer 1

I am not Android developer but isn’t AsyncTask something like new Thread? If yes then you just see “size 0” because Log.d("Size", String.valueOf(items.size())); was executed before new task().execute(); updated your list.