Develop Reference

Get data from server using of AsyncTask

In my program a number of values are stored on the server.
I read these data using of the AsyncTask class from the server.
This is my code:
public class TestActivity extends AppCompatActivity {
private static List<String> mPackName;
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mPackName = new ArrayList<>();
try {
boolean check = new GetDataAsyncTask().execute("1234567").get();
} catch (InterruptedException e) {
} catch (ExecutionException e) {
e.printStackTrace();
e.printStackTrace();
}
}
private class GetDataAsyncTask extends AsyncTask<String, Void, Boolean> {
#Override
protected Boolean doInBackground(String... params) {
final String mCode = params[0];
APIGettingPosts apiGettingPosts = new APIGettingPosts(TestActivity.this, "get_off_code.php");
apiGettingPosts.getOffCode(new APIGettingPosts.OnOffCodeReceived() {
#Override
public void onReceived(List<Posts> posts) {
if (!(posts == null || posts.isEmpty()))
for (int i = 0; i < posts.size(); ++i) {
mPackName.add(posts.get(i).getTitle());
Log.e("mPackName["+String.valueOf(i)+"]",mPackName.get(i));
}
}
});
Log.e("Size of mPackName: ", String.valueOf(mPackName.size()));
for (int i = 0; i < mPackName.size(); ++i)
if (mCode.equals(mPackName.get(i))) {
Log.e("Is Equal: ", mPackName.get(i));
return true;
}
return false;
}
}
}
The program correctly receives the data from the server and stores it in the mPackName list. At the end of the doInBackground function, the program checks if the input value in the GetDataAsyncTask().execute("1234567") function exists in the mPackName list, returns the true value.
Although the input value of the GetDataAsyncTask().execute("1234567") function is in the mPackNamelist, the program returns the false value.
The Log cat output is as follows:
08-28/com.green E/Size of mPackName:: 0
08-28/com.green E/mPackName[0]: 1234567
08-28/com.green E/mPackName[1]: QAZXSWE
08-28/com.green E/mPackName[2]: QWERTYU
The size of the mPackName list is also zero in Log cat , although it has three values {'1234567','QAZXSWE','QWERTYU'}.
The question is: How do I search '1234567' value in the mPackName list to return the true value in check = new GetDataAsyncTask().execute("1234567").get();
code?

Edited Answer
Looks like you even don't need AsyncTask as getOffCode method already runs in background thread.
Remove GetDataAsyncTask class and create a method like below.
private void search(final SearchCallback callback) {
APIGettingPosts apiGettingPosts = new APIGettingPosts(TestActivity.this, "get_off_code.php");
apiGettingPosts.getOffCode(new APIGettingPosts.OnOffCodeReceived() {
#Override
public void onReceived(List<Posts> posts) {
if (!(posts == null || posts.isEmpty())) {
for (int i = 0; i < posts.size(); ++i) {
mPackName.add(posts.get(i).getTitle());
Log.e("mPackName[" + String.valueOf(i) + "]", mPackName.get(i));
if (mCode.equals(mPackName.get(i))) {
callback.onSearchFound(true);
break;
}
}
}
callback.onSearchFound(false);
}
});
}
public interface SearchCallback{
void onSearchFound(boolean success);
}
Then call from onCreate method like below
search(new SearchCallback(){
#Override
public void onSearchFound(boolean success) {
}
});

Try placing a switch in the onPostExecute() method.
EG.
...
private class GetDataAsyncTask extends AsyncTask<String, Void, Boolean> {
#Override
void onPostExecute(Object o){
handleResults()
}
...
void handleResults(){
// Insert your check here
}

Android - Async validation from Parse

I am using Parse in order to store my data. During the user 's registration, I create an AsyncTask to set the result in the calling activity if the user's email exists or not. Here is the code to trigger the validation
View.OnClickListener btnNextClick = new View.OnClickListener() {
#Override
public void onClick(View v) {
if (etEmail == null) {
return;
}
final String email = etEmail.getText().toString();
if (email == null || email.length() == 0) {
etEmail.setError(getResources().getString(
R.string.error_email_is_null)
);
etEmail.requestFocus();
valid = false;
} else {
if (!Common.isValidEmailAddress(email)) {
etEmail.setError(getResources().getString(R.string.error_email_not_valid));
etEmail.requestFocus();
valid = false;
} else {
// validate Email from back end
new CheckEmailAsyncTask(CreateAccountActivity.this, email).execute();
if (emailValid == false) {
etEmail.setError(getResources().getString(R.string.error_email_existed));
etEmail.requestFocus();
valid = false;
}
}
}
if (valid) {
// if valid then going to the next step
Intent intent = new Intent(CreateAccountActivity.this, UpdateUserActivity.class);
intent.putExtra(AppConstant.PARAM_EMAIL, email);
startActivity(intent);
}
}
boolean emailValid;
public void setEmailValid (boolean emailValid) {
this.emailValid = emailValid;
}
};
and this is the code for CheckEmailAysncTask
public class CheckEmailAsyncTask extends AsyncTask<String, Void, Void> {
ProgressDialog progressDialog;
Context context;
CreateAccountActivity createAccountActivity;
String email;
public CheckEmailAsyncTask(CreateAccountActivity createAccountActivity, String email){
this.createAccountActivity = createAccountActivity;
this.context = createAccountActivity;
this.email = email;
progressDialog = new ProgressDialog(context);
}
#Override
protected void onPreExecute() {
this.progressDialog.show();
super.onPreExecute();
}
#Override
protected Void doInBackground(String... params) {
UserDAO userDAO = new UserDAO(context);
try {
int count = userDAO.isUserExists(email);
if (count > 0) {
createAccountActivity.setEmailValid(false);
} else {
createAccountActivity.setEmailValid(true);
}
} catch (ParseException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void result) {
progressDialog.dismiss();
super.onPostExecute(result);
}
}
}
and in UserDAO
public int isUserExists(String email) throws ParseException {
ParseQuery query = new ParseQuery("User");
query.whereEqualTo("email", email);
return query.count();
}
However, in my setup, the code below the AsyncTask will be executed first before the result are returned back to from Parse. How can I just let the rest of the code wait for future return and then continue ? One of the solution that I come up with is to keep looping the calling to the AsyncTask and sleep for while until the result is back

Try this:
if (email == null || email.length() == 0) {
...
}
else if (email != null & email.length() != 0) {
...
}

One solution that I just came up with is sending a callback to the DAO layer function so when the done action is triggered, it will trigger back the callback to move on.
public interface NavCallback {
public void finish();
}
public class MainActivity {
// inside click listener
NavCallback navCallbackError = new NavCallback() {
#Override
public void finish() {
setError();
}
.....
}
and the DAO function will take the callback as the parameters
public void checkExists(String email, NavCallback callback) {
.....
if (callback != null) callback.finish();
}

Custom Loader for endless scrolling

I'm trying to create a custom loader which loads an list of data that works fine but now I want to added endless scrolling in the listview. I thought a logical place would be in the loader since almost all the examples I see on the interwebz have a private field in the custom loader which corresponds with the data to be returned to UI and in the deliverResult there is some code like this
#Override
public void deliverResult(T data) {
T oldData = mData;
mData = data;
if (isStarted()) {
// If the loader is currently started, we can immediately deliver a result
super.deliverResult(mData);
}
}
No I thought that mData still contains the previous list [1,2,3,4,5] cause the loader should cache the data to show it instantaneously on configuration changes. And data is the new list [6,7,8,9,10] for instance. I could just add data to mData, mData.add(data) and we are done. Don't have to repeat the code on multiple places or different adapters. But seemingly this doesn't work, everytime you call restartLoader to load the new data the framework creates a new instance of the Loader. Has anyone else run into this problem before? or should I just do the mData.add(data) in the Adapter or somewhere else in the code.
the full implementation of the custom loader which extends ApiResponseLoader which can also be find below:
public class SearchLoader extends ApiResponseLoader {
private SearchType mSearchType;
private int mOffset;
private String mSearchQuery;
public SearchLoader(Context context, SearchType type, int offset, String query) {
super(context);
mSearchType = type;
mOffset = offset;
mSearchQuery = query;
}
#Override
public ApiResponse loadInBackground() {
try {
Map<String, String> parameters = Utils.parametersMap("q:" + mSearchQuery, "offset:" + String.valueOf(mOffset));
return tryLoadInBackground(parameters);
} catch (Exception e) {
setError(e);
return null;
}
}
public ApiResponse tryLoadInBackground(Map<String, String> parameters) throws Exception {
if (mSearchQuery == null) {
throw new NullPointerException("mSearchQuery should not be null");
}
if (mSearchType == SearchType.A) {
return RestAdapter().searchA(parameters);
} else {
return RestAdapter().searchB(parameters);
}
}
}
public abstract class ApiResponseLoader extends AsyncTaskLoader<ApiResponse> {
private final static String TAG = ApiResponseLoader.class.getSimpleName();
private ApiResponse mApiResponse;
private Exception mError;
public ApiResponseLoader(Context context) {
super(context);
}
public abstract ApiResponse tryLoadInBackground(Map<String, String> parameters) throws Exception;
#Override
protected void onStartLoading() {
if (mApiResponse != null) {
deliverResult(mApiResponse);
}
if (takeContentChanged() || mApiResponse == null) {
forceLoad();
}
}
#Override
protected void onForceLoad() {
super.onForceLoad();
}
#Override
protected void onStopLoading() {
cancelLoad();
}
#Override
public void onCanceled(ApiResponse data) {
// Attempt to cancel the current asynchronous load.
super.onCanceled(data);
}
#Override
protected void onReset() {
// Ensure the loader has been stopped.
onStopLoading();
// At this point we can release the resources associated with 'apps' if needed
if (mApiResponse != null) {
mApiResponse = null;
}
}
#Override
public void deliverResult(ApiResponse data) {
if (isReset()) {
// An async query came in while the loader is stopped. We don't need the result
if (data != null) {
onReleaseResources(data);
}
return;
}
if (mApiResponse != null) {
mApiResponse.mMeta = data.mMeta;
mApiResponse.mSampleList.addAll(data.mSampleList);
} else {
mApiResponse = data;
}
if (isStarted()) {
// If the loader is currently started, we can immediately deliver a result
super.deliverResult(mApiResponse);
}
}
public Exception getError() {
return mError;
}
public void setError(Exception mError) {
this.mError = mError;
}
}

Disable loading in Pull to refresh listview

I am having Pull to Refresh https://github.com/chrisbanes/Android-PullToRefresh as given in this link. Everything works fine. But when my list item finishes, the loading icon and pull to refresh label is still visible. So, how to disable the scrolling when end of list reached?
mainListView.setOnRefreshListener(new OnRefreshListener() {
#Override
public void onRefresh(PullToRefreshBase refreshView) {
String total_bk_count = subCategory .getTotal_Book_Count();
count_of_book = Integer.parseInt(total_bk_count);
listCountt = mainbooksAdpater.getCount();
Log.e("StroreActivity","Total book count---====----====---+"+count_of_book);
Log.e("StroreActivity","list Count---====----====---+"+listCountt);
if(listCountt < count_of_book)
{
int bookCount = Common.getBookCountNumber();
Common.setBookCount(bookCount+1);
String refresh_Pull_Url = Common.getUrlForeCategoryBooks(id, Common.NUMBER_OF_BOOKS_PER_REQUEST);
Log.e("Rathis to Check url", Common.getUrlForeCategoryBooks(id, Common.NUMBER_OF_BOOKS_PER_REQUEST));
PulltoRefreshAsync onCatBooksTaskScroll = new PulltoRefreshAsync(Common.getUrlForeCategoryBooks(id, Common.NUMBER_OF_BOOKS_PER_REQUEST));
onCatBooksTaskScroll.execute();
Log.e("StroreActivity","Total Book count::" + book_count_no);
}
else
{
mainListView.setMode(Mode.DISABLED);
Toast.makeText(getApplicationContext(), "end of list", Toast.LENGTH_SHORT).show();
}
}
});
Asynctask Class:
public class PulltoRefreshAsync extends AsyncTask<Object,Object,Object> {
int refreshCount;
String refresh_URL;
public PulltoRefreshAsync(String url) {
refresh_URL = url;
}
/*
* PulltoRefreshAsync(int i) { refreshCount = i; }
*/
#Override
protected void onPreExecute() {
super.onPreExecute();
Log.e("Checking Purpose", refresh_URL);
}
#Override
protected String doInBackground(Object... arg0) {
JsonParserRefresh jp = new JsonParserRefresh();
Log.e("StroreActivity","Array to String::" + refresh_URL);
String jsonString = jp.getJSONFromURL(refresh_URL);
Log.e("StroreActivity","JsonString::" + jsonString);
jsonParseForCategoryBooksGridScroll(jsonString);
return null;
}
#Override
protected void onPostExecute(Object result) {
super.onPostExecute(result);
/*
* if(mProgressDialog.isShowing()) { mProgressDialog.dismiss(); }
*/
final MainBooksAdapter mainbooksAdpater = new MainBooksAdapter(
StoreActivity.this, R.layout.aa, mainBooksList);
final int old_pos = mainListView.getRefreshableView()
.getFirstVisiblePosition() + 1;
mainListView.setAdapter(mainbooksAdpater);
tvvisiblebookCount.setText("" + mainbooksAdpater.getCount());
/*if(listCountt < count_of_book)
{
mainListView.setMode(Mode.DISABLED);*/
mainListView.post(new Runnable() {
#Override
public void run() {
mainListView.onRefreshComplete();
mainListView.getRefreshableView().setSelection(old_pos);
}
});
//}
mainbooksAdpater.notifyDataSetChanged();
}
}

For other people who might have similat issue:
you don't have to implement it this way
mainListView.post(new Runnable() {
#Override
public void run() {
mainListView.onRefreshComplete();
mainListView.getRefreshableView().setSelection(old_pos);
}
});
instead do just like this :
mainListView.onRefreshComplete();
one more thing I noticed, instead of saving the old pos value to get back to it, why not just use notifyDataSetChanged it leaves the position of the list the way it is, just try not to re-instanciate you list, i.e: mainBooksList = ..., instead try this:
mainBooksList.clear();
mainBooksList.addAll(YOUR DATA);
adapter.notifyDataSetChanged();
voila!
hope this helps someone

Background Service Hangs UI upto the time web service finish its execution?

I have created a webservice class lokks like below, in with in the "onCreate" method of the service i Have called my webservice which takes around 45 seconds to complete its execution for that time my UI gets black that means it Hangs upto the execution of the web service,
below is the code of my service,
public class productService extends Service
{
private static Context _pctx;
static Vector _productsAll = null;
public static void getInstance(Context context) throws Exception
{
if (_pctx == null)
{
_pctx = context;
}
}
#Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
return null;
}
#Override
public void onCreate()
{
try
{
LoadAllProducts();
}
catch (Exception e)
{
e.printStackTrace();
}
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i("LocalService", "Received start id " + startId + ": " + intent);
return START_REDELIVER_INTENT; // 21 sec
}
#Override
public void onDestroy()
{
_productsAll= null;
}
private void LoadAllProducts() throws Exception
{
_productsAll = new Vector();
Exception e = null;
WebResponse myResponse = DataService.GetData("$PR$" , _pctx);
if (Helper.getBoolValueFromString(myResponse.Success))
{
saveMDBData(myResponse.Response);
}
else
{
e = new Exception(myResponse.Response.toString());
}
//cats = null;
if (e != null) {
throw e;
}
}
public static void saveMDBData(StringBuffer pMDBData)
{
Vector Rows;
Vector Cols;
int iRow = 0;
if (pMDBData != null)
{
if (!pMDBData.toString().trim().equals(""))
{
Rows = Helper.getRowsNew(pMDBData);
if (Rows != null)
{
for (iRow = 0; iRow < Rows.size(); iRow++)
{
if (!((String) Rows.elementAt(iRow)).trim().equals(""))
{
Cols = Helper.SplitMultiCharDelimiters((String) Rows.elementAt(iRow), Helper.FIELDDELIMITERS);
assignMDBData(Cols);
}
}
}
}
}
Rows = null;
Cols=null;
}
private static void assignMDBData(Vector pCols)
{
Product myProduct = null;
if (pCols != null)
{
//Create new setting instance
//myProduct = new Product();
myProduct = new Product();
//assign values
myProduct.Id = Helper.getIntValue((String)pCols.elementAt(0));
myProduct.PartNumber = (String)pCols.elementAt(1);
myProduct.Description = (String)pCols.elementAt(2);
myProduct.IdCategory = Helper.getIntValue((String)pCols.elementAt(3));
myProduct.Ideal = Helper.getIntValue((String)pCols.elementAt(4));
myProduct.Taxable = Helper.getBoolValueFromString((String)pCols.elementAt(5));
myProduct.Discountable = Helper.getBoolValueFromString((String)pCols.elementAt(6));
myProduct.LotSize = Helper.getIntValue((String)pCols.elementAt(7));
myProduct.RetailPrice = Helper.getDoubleValue((String)pCols.elementAt(8));
myProduct.ListPrice = Helper.getDoubleValue((String)pCols.elementAt(9));
myProduct.TotalOnHand = Helper.getIntValue((String)pCols.elementAt(10));
myProduct.TotalOnOrder = Helper.getIntValue((String)pCols.elementAt(11));
myProduct.IsPrepack = Helper.getBoolValueFromString((String)pCols.elementAt(12));
//myProduct.Breakdown = (String)pCols.elementAt(13);
myProduct.NoInventory = Helper.getBoolValueFromString((String)pCols.elementAt(13));
myProduct.IsCollection = Helper.getBoolValueFromString((String)pCols.elementAt(14));
myProduct.Followup = Helper.getIntValue((String)pCols.elementAt(15));
myProduct.PctDiscount = Helper.getDoubleValue((String)pCols.elementAt(16));
myProduct.IdGroup = Helper.getIntValue((String)pCols.elementAt(17));
myProduct.Points = Helper.getIntValue((String)pCols.elementAt(18));
myProduct.IsVitamin = Helper.getBoolValueFromString((String)pCols.elementAt(19));
myProduct.PusChange = Helper.getIntValue((String)pCols.elementAt(20));
myProduct.MovedToCloseout = Helper.getDateDataSync((String)pCols.elementAt(21));
myProduct.OnHandDelta = Helper.getIntValue((String)pCols.elementAt(24));
//save processed setting to persistent collection
_productsAll.addElement(myProduct);
//release saved setting in)stance
myProduct = null;
}
}
}
Anyone please help me to sort out the probelm,
I am Stuck Here,
Thanks in Advance!

For Background Services use the AsyncTask which creates background threads so doesn't effect your main UI.
Here is the Code:
public class DownloadData extends AsyncTask<String, String, String> {
#Override
public void onPreExecute() {
// Do Some Task before background thread runs
}
#Override
protected String doInBackground(String... arg0) {
// To Background Task Here
return null;
}
#Override
protected void onProgressUpdate(String... progress) {
// publish progress here
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
// Do some Task after Execution
}
}
For more details: See this one
http://developer.android.com/reference/android/os/AsyncTask.html