My problem is very basic, however I can't see the solution to it. That's my 3rd project on Android.
So far I was using fragments with a ListView declared in it, onCreateView where I was inflating my ListView and onActivityCreated to initialize the layout. Now I want to do the same but using ListFragment.
I was using this exmaple as reference: http://developer.android.com/training/basics/fragments/creating.html
Below is modified code that I used for Fragment with a ListView. I have changed this to work with a ListFragment but without success. Can someone help me out? Thank you in advance.
public class PlayersListFragment extends ListFragment {
OnPlayerSelectedListener mCallback;
// URL to make request
private static String URL = Utils.URL;
private static int userID;
ArrayList<HashMap<String, Object>> playersList;
ListView playerView;
private Dialog pDialog;
// The container Activity must implement this interface so the frag can
// deliver messages
public interface OnPlayerSelectedListener {
/** Called by HeadlinesFragment when a list item is selected */
public void onPlayerSelected(int position);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// We need to use a different list item layout for devices older than
// Honeycomb
int layout = Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB ? android.R.layout.simple_list_item_activated_1
: android.R.layout.simple_list_item_1;
// Create an array adapter for the list view, using the Ipsum headlines
// array
setRetainInstance(true);
new PlayersLoadTask().execute();
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initLayout();
}
public boolean onOptionsItemSelected(MenuItem item) {
return false;
}
private void initLayout() {
if(getActivity().getIntent()!=null) {
userID = getActivity().getIntent().getIntExtra("id", 0);
} else {
return;
}
playerView = (ListView) getActivity().findViewById(R.id.list);
playersList = new ArrayList<HashMap<String, Object>>();
int[] colors = {0, 0xFFFF0000, 0}; // red for the example
}
@Override
public void onStart() {
super.onStart();
// When in two-pane layout, set the listview to highlight the selected
// list item
// (We do this during onStart because at the point the listview is
// available.)
if (getFragmentManager().findFragmentById(R.id.playerDetailFragment) != null) {
getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
}
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
// This makes sure that the container activity has implemented
// the callback interface. If not, it throws an exception.
try {
mCallback = (OnPlayerSelectedListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnPlayerSelectedListener");
}
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
// Notify the parent activity of selected item
mCallback.onPlayerSelected(position);
// Set the item as checked to be highlighted when in two-pane layout
getListView().setItemChecked(position, true);
}
class PlayersLoadTask extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
pDialog = ProgressDialog.show(getActivity(), "",
"Loading. Please wait...", true);
}
@Override
protected String doInBackground(String... params) {
try {
ArrayList<BasicNameValuePair> parameters = new ArrayList<BasicNameValuePair>();
parameters.add(new BasicNameValuePair("request", "getPlayers"));
parameters.add(new BasicNameValuePair("clubid", Integer
.toString(userID)));
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(URL);
httpPost.setEntity(new UrlEncodedFormEntity(parameters,
("ISO-8859-1")));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
// if this is null the web service returned an empty page
if (httpEntity == null) // response is empty so exit out
return null;
String jsonString = EntityUtils.toString(httpEntity);
if (jsonString != null && jsonString.length() != 0)
{
JSONArray jsonArray = new JSONArray(jsonString);
for (int i = 0; i < jsonArray.length(); i++) {
HashMap<String, Object> map = new HashMap<String, Object>();
JSONObject jsonObject = (JSONObject) jsonArray.get(i);
int id = jsonObject.getInt("id");
String name = jsonObject.getString("name");
map.put("id", id);
map.put("name", name);
playersList.add(map);
}
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} catch (Exception e) {
Log.e("ERROR SOMEWHERE!!!! ", e.toString());
}
return null;
}
@Override
protected void onPostExecute(String file_url) {
if (pDialog.isShowing())
pDialog.dismiss();
if (playersList.size() == 0) {
Toast.makeText(getActivity(), "No players in a list",
Toast.LENGTH_SHORT).show();
} else {
playerView.setAdapter(new PlayerListAdapter( // <<== EXCEPTION HERE
getActivity(), R.id.player_list_id,
playersList));
}
}
}
}
And off course a stacktrace from a LogCat which points on this line : playerView.setAdapter(new PlayerListAdapter(
12-18 11:34:30.181: E/AndroidRuntime(16436): FATAL EXCEPTION: main
12-18 11:34:30.181: E/AndroidRuntime(16436): java.lang.NullPointerException
12-18 11:34:30.181: E/AndroidRuntime(16436): at com.statsports.statisticalandroid.PlayersListFragment$PlayersLoadTask.onPostExecute(PlayersListFragment.java:199)
12-18 11:34:30.181: E/AndroidRuntime(16436): at com.statsports.statisticalandroid.PlayersListFragment$PlayersLoadTask.onPostExecute(PlayersListFragment.java:1)
12-18 11:34:30.181: E/AndroidRuntime(16436): at android.os.AsyncTask.finish(AsyncTask.java:631)
12-18 11:34:30.181: E/AndroidRuntime(16436): at android.os.AsyncTask.access$600(AsyncTask.java:177)
12-18 11:34:30.181: E/AndroidRuntime(16436): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
12-18 11:34:30.181: E/AndroidRuntime(16436): at android.os.Handler.dispatchMessage(Handler.java:99)
12-18 11:34:30.181: E/AndroidRuntime(16436): at android.os.Looper.loop(Looper.java:137)
12-18 11:34:30.181: E/AndroidRuntime(16436): at android.app.ActivityThread.main(ActivityThread.java:5103)
12-18 11:34:30.181: E/AndroidRuntime(16436): at java.lang.reflect.Method.invokeNative(Native Method)
12-18 11:34:30.181: E/AndroidRuntime(16436): at java.lang.reflect.Method.invoke(Method.java:525)
12-18 11:34:30.181: E/AndroidRuntime(16436): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
12-18 11:34:30.181: E/AndroidRuntime(16436): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
12-18 11:34:30.181: E/AndroidRuntime(16436): at dalvik.system.NativeStart.main(Native Method)
That's how I solved my problem. Seem's you must include setListAdapter() in either onCreate() or onActivityCreated(). Code for future reference:
public class PlayersListFragment extends ListFragment {
OnPlayerSelectedListener mCallback;
// URL to make request
private static String URL = Utils.URL;
private static int userID;
ArrayList<HashMap<String, Object>> playersList;
ListView playerView;
private ProgressDialog pDialog;
// The container Activity must implement this interface so the frag can
// deliver messages
public interface OnPlayerSelectedListener {
/** Called by HeadlinesFragment when a list item is selected */
public void onPlayerSelected(int position);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
initLayout();
new PlayersLoadTask().execute();
int layout = Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB ?
android.R.layout.simple_list_item_activated_1 : android.R.layout.simple_list_item_1;
setListAdapter(new PlayerListAdapter(getActivity(), layout, playersList));
}
public boolean onOptionsItemSelected(MenuItem item) {
return false;
}
private void initLayout() {
if(getActivity().getIntent()!=null) {
userID = getActivity().getIntent().getIntExtra("id", 0);
} else {
return;
}
playerView = getListView();
playersList = new ArrayList<HashMap<String, Object>>();
}
@Override
public void onStart() {
super.onStart();
// When in two-pane layout, set the listview to highlight the selected
// list item
// (We do this during onStart because at the point the listview is
// available.)
if (getFragmentManager().findFragmentById(R.id.playerDetailFragment) != null) {
playerView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
}
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
// This makes sure that the container activity has implemented
// the callback interface. If not, it throws an exception.
try {
mCallback = (OnPlayerSelectedListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnPlayerSelectedListener");
}
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
// Notify the parent activity of selected item
mCallback.onPlayerSelected(position);
// Set the item as checked to be highlighted when in two-pane layout
playerView.setItemChecked(position, true);
}
class PlayersLoadTask extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
pDialog = ProgressDialog.show(getActivity(), "",
"Loading. Please wait...", true);
}
@Override
protected String doInBackground(String... params) {
try {
ArrayList<BasicNameValuePair> parameters = new ArrayList<BasicNameValuePair>();
parameters.add(new BasicNameValuePair("request", "getPlayers"));
parameters.add(new BasicNameValuePair("clubid", Integer
.toString(userID)));
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(URL);
httpPost.setEntity(new UrlEncodedFormEntity(parameters,
("ISO-8859-1")));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
// if this is null the web service returned an empty page
if (httpEntity == null) // response is empty so exit out
return null;
String jsonString = EntityUtils.toString(httpEntity);
if (jsonString != null && jsonString.length() != 0)
{
JSONArray jsonArray = new JSONArray(jsonString);
for (int i = 0; i < jsonArray.length(); i++) {
HashMap<String, Object> map = new HashMap<String, Object>();
JSONObject jsonObject = (JSONObject) jsonArray.get(i);
int id = jsonObject.getInt("id");
String name = jsonObject.getString("name");
map.put("id", id);
map.put("name", name);
playersList.add(map);
}
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} catch (Exception e) {
Log.e("ERROR SOMEWHERE!!!! ", e.toString());
}
return null;
}
@Override
protected void onPostExecute(String file_url) {
if (pDialog.isShowing())
pDialog.dismiss();
if (playersList.size() == 0) {
Toast.makeText(getActivity(), "No players in a list",
Toast.LENGTH_SHORT).show();
} else if(playerView != null) {
setListAdapter(new PlayerListAdapter(getActivity(), R.id.player_list_id, playersList));
/*playerView.setAdapter(new PlayerListAdapter(
getActivity(), R.id.player_list_id,
playersList));*/
}
}
}