Develop Reference

NullPointerException: Google Spreadsheet, doInBackground

I get the NullPointerException and I can't figure out what's wrong. I've tried only to bring the necessary code.
I have 3 classes: MainActivity, GoogleCommunicator and CustomAdapter.
The error is caused by following in CustomAdapter:
mActivity.updateBought(position, "1");
The errors I get are line 283 and 277 which are:
283: URL listFeedUrl = mWorksheet.getListFeedUrl();
277: private class UpdateBought extends AsyncTask<Void, Void, String>
The logcat:
3011-3026/com.example.andb.apop_l6_google_communicator_app E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
Process: com.example.andb.apop_l6_google_communicator_app, PID: 3011
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:300)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.net.URL com.google.gdata.data.spreadsheet.WorksheetEntry.getListFeedUrl()' on a null object reference
at com.example.andb.apop_l6_google_communicator_app.GoogleCommunicator$UpdateBought.doInBackground(GoogleCommunicator.java:283)
at com.example.andb.apop_l6_google_communicator_app.GoogleCommunicator$UpdateBought.doInBackground(GoogleCommunicator.java:277)
at android.os.AsyncTask$2.call(AsyncTask.java:288)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
          
MainActivity
public class MainActivity extends ActionBarActivity implements AdapterView.OnItemClickListener{
public GoogleCommunicator mGCom = new GoogleCommunicator(this,"torprode#gmail.com");
TextView tvStatus;
EditText etAdd;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tvStatus = (TextView) findViewById(R.id.tvStatus);
doSomeGoogleStuff();
buttonListener();
update();
}
private void doSomeGoogleStuff(){
mGCom.setupFeed("mandatoryProject","BuyMe");
}
private void drawListview() {
ListAdapter listAdapter = new CustomAdapter(this, mGCom.listItem, mGCom.listBought);
ListView listView = (ListView) findViewById(R.id.lv_items);
listView.setAdapter(listAdapter);
}
public void updateBought(int name, String bought) {
mGCom.updateBought(name, bought);
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
}
}
GoogleCommunicator
public class GoogleCommunicator {
//Spreadsheet communication
private static final String mScope = "oauth2:https://www.googleapis.com/auth/userinfo.profile https://spreadsheets.google.com/feeds https://docs.google.com/feeds";
private MainActivity mActivity;
private SpreadsheetService mSpreadSheetService;
private SpreadsheetFeed mFeed;
private String mSpreadsheetName;
private String mWorksheetName;
private SpreadsheetEntry mSpreadsheet;
private WorksheetEntry mWorksheet;
private String itemName;
private int itemNameIndex;
private String itemBought;
//Constructor
public GoogleCommunicator(MainActivity activity, String email) {
mEmail = email;
mActivity = activity; //possibility for callback to method in activity class
}
//Method to be called from your application.
//Creates an instance of SetupFeedTask (an AsyncTask) and executes it
public void setupFeed(String spreadsheet_name, String worksheet_name){
mSpreadsheetName = spreadsheet_name;
mWorksheetName = worksheet_name;
new SetupFeedTask().execute();
}
public void updateBought(int name, String bought) {
itemNameIndex = name;
itemBought = bought;
new UpdateBought().execute();
}
//AsyncTask that handles network comminucation e.t.c.
private class SetupFeedTask extends AsyncTask<Void, Void, String> {
//Executes in its own "worker thread" and doesnt block the main UI thread
#Override protected String doInBackground(Void... params) {
// Do work
mToken = fetchToken();
mSpreadSheetService = new SpreadsheetService("MySpreadsheetService");
mSpreadSheetService.setAuthSubToken(mToken);
URL feed_url;
try {
feed_url = new URL("https://spreadsheets.google.com/feeds/spreadsheets/private/full");
mFeed = mSpreadSheetService.getFeed(feed_url, SpreadsheetFeed.class);
}catch(MalformedURLException e){
//TODO: handle exception
Log.v(TAG, "MalformedURLException");
return null;
}catch(ServiceException e){
//TODO: handle exception
Log.v(TAG, "ServiceException");
return null;
}catch(IOException e){
//TODO: handle exception
Log.v(TAG, "IOException");
return null;
}
try{
List<SpreadsheetEntry> spreadsheets = mFeed.getEntries();
// Iterate through all of the spreadsheets returned
for (SpreadsheetEntry spreadsheet : spreadsheets) {
if (spreadsheet.getTitle().getPlainText().equals(mSpreadsheetName)) {
List<WorksheetEntry> worksheets = spreadsheet.getWorksheets();
//Iterate through worksheets
for (WorksheetEntry worksheet : worksheets) {
if (worksheet.getTitle().getPlainText().equals(mWorksheetName)) {
mSpreadsheet = spreadsheet;
mWorksheet = worksheet;
Log.v(TAG,"Spreadsheet and Worksheet is now setup.");
}
}
}
}
}catch(ServiceException e){
//TODO: handle exception
Log.v(TAG, "Service Exception");
return null;
}catch(IOException e){
//TODO: handle exception
Log.v(TAG, "IO Exception");
return null;
}
//Just for the example.. mToken not important to return
return mToken;
}
//Call back that is called when doInBackground has finished.
//Executes in main UI thread
#Override protected void onPostExecute(String result) {
//TODO: Notify rest of application, e.g.:
// * Send broadcast
// * Send message to a handler
// * Call method on Activity
}
//Helper method
private String fetchToken(){
try {
return GoogleAuthUtil.getToken(mActivity, mEmail, mScope);
} catch (UserRecoverableAuthException userRecoverableException) {
// GooglePlayServices.apk is either old, disabled, or not present, which is
// recoverable, so we need to show the user some UI through the activity.
//TODO:
if(mActivity instanceof MainActivity){
((MainActivity)mActivity).handleException(userRecoverableException);
if(D) Log.e(TAG,"UserRecoverableAuthException");
}
} catch (GoogleAuthException fatalException) {
//TODO:
//onError("Unrecoverable error " + fatalException.getMessage(), fatalException);
if(D) Log.e(TAG,"GoogleAuthException");
} catch (IOException ioException){
if(D) Log.e(TAG,"IOException");
}
return null;
}
}
private class UpdateBought extends AsyncTask<Void, Void, String> {
#Override
protected String doInBackground(Void... params) {
try {
URL listFeedUrl = mWorksheet.getListFeedUrl();
ListFeed listFeed = mSpreadSheetService.getFeed(listFeedUrl, ListFeed.class);
ListEntry row = listFeed.getEntries().get(itemNameIndex);
row.getCustomElements().setValueLocal("bought", itemBought);
row.update();
} catch (IOException e) {
e.printStackTrace();
} catch (ServiceException e) {
e.printStackTrace();
}
return null;
}
}
}
CustomAdapter
class CustomAdapter extends ArrayAdapter<String> {
ArrayList boughtList;
MainActivity mActivity = new MainActivity();
CustomAdapter(Context context, ArrayList<String> item, ArrayList<String> bought) {
super(context, R.layout.custom_listview, item);
boughtList = bought;
}
#Override
public View getView(final int position, View convertView, final ViewGroup parent) {
LayoutInflater listViewInflater = (LayoutInflater.from(getContext()));
final View customView = listViewInflater.inflate(R.layout.custom_listview, parent, false);
final String foodItem = getItem(position);
TextView foodText = (TextView) customView.findViewById(R.id.tv_Item);
final CheckBox checkBox = (CheckBox) customView.findViewById(R.id.cb_checked);
foodText.setText(foodItem);
String foodBought = String.valueOf(boughtList.get(position));
int foodBoughtInt = Integer.parseInt(foodBought);
if (foodBoughtInt == 1) {
checkBox.setChecked(true);
} else {
checkBox.setChecked(false);
}
checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if (checkBox.isChecked()) {
System.out.println("Jep");
mActivity.updateBought(position, "1");
} else {
System.out.println("Nope");
mActivity.updateBought(position, "0");
}
}
});
return customView;
}
}

You are encountering a race condition. You have to asynchronous tasks that execute, and the second asynchronous task depends on the first task to be done for it to work correctly. Because both tasks are done asynchronously, they are done in the background, on separate threads. Your setupFeed method is not done working, and then you start your updateBought method on a new thread. What happens is that updateBought begins while mWorksheet is still null. You will have to reorganize your code logic to avoid this race condition. What I have done in the past when I have two async tasks is to put the second asynchronous task in onPostExecute() of the first async task, because onPostExecute only occurs once doInBackground is finished.
Here is an execellent article on AsyncTasks and Threads from the developer guides.

ProgressDialog Android

I am trying to use ProgressDialog. when i run my app the Progress Dialog box show and disappear after 1 second. I want to show it on completion of my process.. Here is my code:
public class MainActivity extends Activity {
android.view.View.OnClickListener mSearchListenerListener;
private ProgressDialog dialog;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new YourCustomAsyncTask().execute(new String[] {null, null});
}
private class YourCustomAsyncTask extends AsyncTask <String, Void, Void> {
protected void onPreExecute() {
dialog = new ProgressDialog(MainActivity.this);
dialog.setMessage("Loading....");
dialog.setIndeterminate(true);
dialog.setCancelable(true);
dialog.show(); //Maybe you should call it in ruinOnUIThread in doInBackGround as suggested from a previous answer
}
protected void doInBackground(String strings) {
try {
// search(strings[0], string[1]);
runOnUiThread(new Runnable() {
public void run() {
// updateMapWithResult(); //Or call it onPostExecute before progressDialog's dismiss. I believe this method updates the UI so it should run on UI thread
}
});
} catch(Exception e) {
}
}
#Override
protected void onPostExecute(Void params) {
dialog.dismiss();
//result
}
#Override
protected Void doInBackground(String... params) {
// TODO Auto-generated method stub
return null;
}
}
}
Updated Question:
#Override
public void onCreate(SQLiteDatabase db) {
mDatabase = db;
Log.i("PATH",""+mDatabase.getPath());
mDatabase.execSQL(FTS_TABLE_CREATE);
loadDictionary();
}
/**
* Starts a thread to load the database table with words
*/
private void loadDictionary() {
new Thread(new Runnable() {
public void run() {
try {
loadWords();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}).start();
}
private void loadWords() throws IOException {
Log.d(TAG, "Loading words...");
for(int i=0;i<=25;i++)
{ //***//
final Resources resources = mHelperContext.getResources();
InputStream inputStream = resources.openRawResource(raw_textFiles[i]);
//InputStream inputStream = resources.openRawResource(R.raw.definitions);
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
try {
StringBuilder sb = new StringBuilder();
while ((word = reader.readLine()) != null)
{
sb.append(word);
// Log.i("WORD in Parser", ""+word);
}
String contents = sb.toString();
StringTokenizer st = new StringTokenizer(contents, "||");
while (st.hasMoreElements()) {
String row = st.nextElement().toString();
String title = row.substring(0, row.indexOf("$$$"));
String desc = row.substring(row.indexOf("$$$") + 3);
// Log.i("Strings in Database",""+title+""+desc);
long id = addWord(title,desc);
if (id < 0) {
Log.e(TAG, "unable to add word: " + title);
}
}
} finally {
reader.close();
}
}
Log.d(TAG, "DONE loading words.");
}
I want to show ProgressDialogue box untill all words are not entered in the database. This code is in inner calss which extends SQLITEHELPER. so how to can i use ProgressDialogue in that inner class and run my addWords() method in background.

You cannot have this
runOnUiThread(new Runnable() {
public void run() {
// updateMapWithResult(); //Or call it onPostExecute before progressDialog's dismiss. I believe this method updates the UI so it should run on UI thread
}
});
in your doInBackground().
Progress dialog doesn't take priority when there is some other action being performed on the main UI thread. They are intended only when the actions are done in the background. runonUIthread inside doInBackground will not help you. And this is normal behavior for the progressdialog to be visible only for few seconds.

You have two doInBackground() methods inside your AsyncTask Class. Remove the runOnUiThread() from First doInBackground() and move it to second doInBackground() which has #Override annotation.
I don't know whether you wantedly written two doInBackground() methods or by mistake but it is not good to have such confusion between the Method. Your AsyncTask is not calling the first doInBackground() and it will call doInBackground() which has #Override annotation. So your ProgressDialog is dismissed in 1 second of time as it returns null immediately.

Performing data loading unitl succesfull or user break

In my app I performing loading data from web and then displaying it to user. Before loading data app shows progress dialog. I have problem if user locks phone in the middle of loading operation, or server is overloaded and can't respond in time my application freezes, because it doesn't dismiss progress dialog, or in some cases it crashes because lack on needed data.
If some error happened while loading data I want show some dialog to user to let him know about error and ask him should application repeat last request. I tried to use AlertDialog for it, but I haven't succeed.
Here is code of one activity (There is no progress dialog here, but it demonstrates how I loading data):
#EActivity(R.layout.layout_splash)
#RoboGuice
public class SplashScreenActivity extends Activity {
#Inject
private AvtopoiskParserImpl parser;
#Bean
BrandsAndRegionsHolder brandsAndRegionsHolder;
#ViewById(R.id.splash_progress)
ProgressBar progressBar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
loadData();
}
#Background
protected void loadData() {
publishProgress(10);
LinkedHashMap<String, Integer> brands = null;
try {
brands = parser.getBrands();
} catch (IOException e) {
Log.e(e.getMessage());
}
publishProgress(50);
LinkedHashMap<String, Integer> regions = null;
try {
regions = parser.getRegions();
} catch (IOException e) {
Log.e(e.getMessage());
}
publishProgress(70);
populateData(brands, regions);
}
#UiThread
protected void populateData(LinkedHashMap<String, Integer> brands, LinkedHashMap<String, Integer> regions) {
Intent intent = new Intent(SplashScreenActivity.this, SearchActivity_.class);
brandsAndRegionsHolder.brandsMap = brands;
brandsAndRegionsHolder.regionsMap = regions;
publishProgress(100);
startActivity(intent);
finish();
}
#UiThread
void publishProgress(int progress) {
progressBar.setProgress(progress);
}
}
parser.getBrands() and parser.getRegions() are loading data from the web.
I want to do something like this:
boolean repeatRequest = true;
while (repeatRequest) {
try {
brands = parser.getBrands();
repeatRequest = false;
} catch (IOException e) {
Log.e(e.getMessage());
repeatRequest = showErrorDialog();
}
}
But I didn't manage to do so because this code executes in background thread, but dialog should be shown in UI thread.
I believe that it should be standard approach of doing so, but didn't manage to find it.
Any ides how can I implement this?

The best way is to use AsyncTask.
private class LoadDataTask extends AsyncTask<Void, Integer, Object> {
private ProgressDialog mProgress;
protected Object doInBackground(Void... params) {
// This method runs in background
Object result = null;
try {
result = parser.parse();
} catch (Exception e) {
result = e.getMessage();
}
return result;
}
protected void onProgressUpdate(Integer... progress) {
// This method runs in UI thread
mProgress.setProgress(progress[0]);
}
protected void onPreExecute() {
// This method runs in UI thread
mProgress = new ProgressDialog(context);
mProgress.show();
}
protected void onPostExecute(Object result) {
// This method runs in UI thread
mProgress.dismiss();
if (result instance of String) {
// Here you can launch AlertDialog with error message and proposal to retry
showErrorDialog((String) result);
} else {
populateData(result);
}
}
}

Updating main thread tablelayout from async thread

I have a problem with updating my table-layout from my async class.
MY async class is fetching XML data so I don't block the main thread. My logs show the XML data is coming through but I don't know how to update my view with the data.
So I am attempting to put the data in tablerows and add the rows to the TableLayout but the logs show errors suggesting the Async class is not allowed to update my TableLayout view.
My code is as follows:
public class RemotePrimary extends Activity {
private static String SERVER_PATH = "http://test2.icerge.com/";
private static String XML_FILE1 = "samplexml";
//private static String SERVER_PATH = "http://tqs.mamlambo.com/";
//private static String XML_FILE1 = "scores.jsp";
private String[] data = new String[10];
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
TableLayout datatable = (TableLayout)findViewById(R.id.TableLayout_data);
Downloader downloader = new Downloader();
downloader.execute(SERVER_PATH + XML_FILE1, datatable);
}
private class Downloader extends AsyncTask<Object, String, Boolean>{
TableLayout table;
#Override
protected Boolean doInBackground(Object... params) {
// TODO Auto-generated method stub
String path = (String)params[0];
table = (TableLayout)params[1];
XmlPullParser xmldata = null;
try {
URL serverPath = new URL(path);
xmldata = XmlPullParserFactory.newInstance().newPullParser();
xmldata.setInput(serverPath.openStream(), null);
addRecord(xmldata, table);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return true;
}
#Override
protected void onProgressUpdate(String... values) {
// TODO Auto-generated method stub
//super.onProgressUpdate(values);
}
private boolean addRecord(XmlPullParser data, TableLayout table){
int eventType = -1;
boolean bFoundScores = false;
//find some records from xml
while(eventType != XmlResourceParser.END_DOCUMENT){
if( eventType == XmlResourceParser.START_TAG ){
//get the name of the tag(eg scores or score)
String strName = data.getName();
if( strName.equals("node") ){
bFoundScores = true;
String scoreValue = data.getAttributeValue(null, "Title");
String scoreRank = data.getAttributeValue(null, "Type");
String scoreUserName = data.getAttributeValue(null, "Nid");
Log.e("ADDING: ", scoreValue);
//Log.e("RETRIEVED", "collected : "+scoreValue+", "+scoreRank+", "+scoreUserName);
//publishProgress(scoreValue, scoreRank, scoreUserName);
TableRow newRow = new TableRow(RemotePrimary.this);
TextView rowText = new TextView(RemotePrimary.this);
rowText.setText(scoreValue);
newRow.addView(rowText);
table.addView(newRow);
}
}
try {
eventType = data.next();
} catch (XmlPullParserException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return true;
}
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
}
#Override
protected void onPostExecute(Boolean result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
}
}//close Downloader class
}//close RemotePrimary class
It's a bit much I know but I'll appreciate any help.
Thanks a great deal :-)

You can only make changes from the UI on the UI thread. The AsyncTask gives you an easy place to do this via onPostExecute. As it says in the docs, onPostExecute is always performed on the UI thread.
In doInBackground, do all of the hard work of building up the structured data that wish to display. Return that data so that it will be passed into onPostExecute, then in there add the appropriate table rows.

Android: How do I make a ListView update itself periodically?

I never got this working in a straightforward manner. Sorry if I'm being a little vague. I'll try to elaborate on what I'm trying to do. I am trying to build a listview that grabs its data from a webservice. Once I initialize a listview, I want to keep polling the webserver periodically and update the contents of the listview. For this I am doing something like this:
public class SampleAutoUpdateList extends Activity {
//Autoupdate handler
private Handler handler = new Handler();
private Runnable updater = new Runnable() {
public void run() {
/*
* Update the list
*/
try {
Log.i("UPDATE", "Handler called");
searchAdapter = getFeed(URL);
searchAdapter.notifyDataSetChanged();
handler.postDelayed(this, Configuration.REFRESH_INTERVAL);
} catch(Exception e) {
Log.e("UPDATE ERROR", e.getMessage());
}
}
};
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.linearmode);
this.context = this;
searchAdapter = getFeed(URL);
LinearLayout l2 = (LinearLayout) findViewById(R.id.secondaryLayout);
ListView list = new ListView(context);
l2.addView(list);
// display UI
UpdateDisplay(list);
updater.run();
}
private SearchAdapter getFeed(String URL) {
try
{
SearchHandler handler = new SearchHandler();
URL url = new URL(URL);
String data = convertStreamToString(url.openStream());
data = data.substring(data.indexOf('['), data.length()-1);
handler.parseJSON(data);
return handler.getFeed();
}
catch (Exception ee)
{
// if we have a problem, simply return null
Log.e("getFeed", ee.getMessage());
return null;
}
}
private void UpdateDisplay(View searchView) {
// TODO Auto-generated method stub
// TODO Auto-generated method stub
searchList = (ListView) searchView;
myProgressDialog = ProgressDialog.show(this,
"Please wait...", "Loading search....", true);
new Thread() {
public void run() {
try{
Thread.sleep(2000);
} catch (Exception e) { }
runOnUiThread(new Runnable() {
#Override
public void run() {
if (searchAdapter == null)
{
Log.e("ERROR", "No Feed Available");
return;
}
searchAdapter.setContext(context);
searchList.setAdapter(searchAdapter);
searchList.setSelection(0);
}
});
// Dismiss the Dialog
myProgressDialog.dismiss();
}
}.start();
}
}
And the SearchHandler class is simple:
public class SearchHandler extends DefaultHandler {
SearchAdapter _adapter;
SearchItem _item;
public SearchHandler()
{
}
public SearchAdapter getFeed()
{
return _adapter;
}
public void parseJSON(String data) {
// TODO Auto-generated method stub
_adapter = new SearchAdapter();
JSONArray parseArray;
try {
parseArray = new JSONArray(data);
for (int i=0; i < parseArray.length(); i++) {
SearchItem item = new SearchItem();
JSONObject jsonUser = parseArray.getJSONObject(i);
item.set_from(jsonUser.getString ("from"));
item.set_msg(jsonUser.getString("msg"));
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
No matter what I do, the handler gets called and the new items are fetched, but the list is never refreshed... Any ideas on what could be going wrong?

Well, it is a little bit difficult to follow your code, since you only have a fragment of it, and few of the really relevant bits. For example, based on your available code, your list should be forever empty, since you never associate the searchAdapter with a ListView...at least in the code you have shown.
That being said, the following lines seem particularly odd:
searchAdapter = getFeed(URL);
searchAdapter.notifyDataSetChanged();
I am going to assume that getFeed() (not shown) creates a new ListAdapter of some sort. If getFeed() is creating a new ListAdapter, there is no need to call notifyDataSetChanged() on it, as its data set hasn't changed -- it's brand new. Moreover, unless you are associating this new ListAdapter to your ListView, the new ListAdapter will have no effect.
If I'm barking up the wrong tree, consider adding lines to your sample showing the implementation of getFeed() and where you are using searchAdapter.