I have an interesting problem that I've never run into in programming before. I have an onClickListener that does a lot of username and password checks (makes sure the username is proper length, not taken, etc). I'm using MobDB, and I was using a conditional statement that would return a row if the username already existed. The problem is that the Listener skips the DB and goes to the final check that, if everything works, posts a new username and password to my DB. How can I make it wait for a response from the DB before skipping to the last check?
Here is the relevant code:
usernamecheck3 = true;
MobDB.getInstance().execute(APP_KEY, null, rd, null, false, new MobDBResponseListener() {
#Override public void mobDBSuccessResponse() {
usernamecheck3 = false;
Log.e("mobdbSuccess:", "success");
}
#Override public void mobDBResponse(Vector<HashMap<String, Object[]>> row) {
}
#Override public void mobDBResponse(String jsonObj) {
/*Log.e("mobdbSuccess:", "jsonObj");
Log.e("mobdbSuccess:", jsonObj);
JSONObject mainObject;
try {
mainObject = new JSONObject(jsonObj);
// need to parse the json object.
} catch (JSONException e1) {
e1.printStackTrace();
} */
}
#Override public void mobDBFileResponse(String fileName, byte[] fileData) {
//get file name with extension and file byte array
}
#Override public void mobDBErrorResponse(Integer errValue, String errMsg) {
usernamecheck3 = false;
Log.e("doesnt", "work");
}
});
if(usernamecheck3 == false){
Toast.makeText(getApplicationContext(), "Username is taken, please choose another", Toast.LENGTH_SHORT).show();
}
Basically the check always returns true, and then logcat will say mobdbSuccess: success, which should have set the Bool to false.
Thanks.
MobDBResponseListener is executing on a different thread. What happens here is that the processing is split, while a thread is doing the query, the main thread on which you added the listener, skips right ahead to the validation. Your best bet is to place the validation inside the MobDBResponseListener, on the mobDBResponse method.
Try to debug your code and calls, the Listener may be using an async task. If so, you may do anything you please from the response method, as it will be executing in the main thread again. Otherwise, you should look at solutions that handle threaded execution like Handlers
Related
I am getting data (List) from an API and I am trying to update my AutcompleteTextView with this data.
This is how I currently do :
I have a TextWatcher which calls a the method to get the data in afterTextChanged, so every time the user stops typing the method is called, and the adapter is notified with ``notifyDataSetChanged :
//in onCreate
addressAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_dropdown_item_1line,suggestions_address);
at_address.setAdapter(addressAdapter);
...
#Override
public void afterTextChanged(Editable s) {
autoComplete(s);
addressAdapter.notifyDataSetChanged();
//suggestions_address is the updated list, and when I print it I can see the
//results so it is not empty
Log.i("addresses",suggestions_address.toString());
}
...
class SuggestionQueryListener implements ResultListener<List<String>> {
#Override
public void onCompleted(List<String> data, ErrorCode error) {
if (error != ErrorCode.NONE) {
Toast.makeText(MainActivity2.this,error.toString(),Toast.LENGTH_LONG).show();
} else {
suggestions_address.clear();
for(int i = 0;i<data.size();i++){
suggestions_address.add(data.get(i));
}
}
}
}
public void autoComplete(CharSequence s) {
try {
String term = s.toString();
TextSuggestionRequest request = null;
request = new TextSuggestionRequest(term).setSearchCenter(new GeoCoordinate(48.844900, 2.395658));
request.execute(new SuggestionQueryListener());
if (request.execute(new SuggestionQueryListener()) != ErrorCode.NONE) {
//Handle request error
//...
}
} catch (IllegalArgumentException ex) {
//
}
}
But it seems that the adapter is not really updated because it doesn't show the suggestions when I type something.
Also, before doing this with an AutoCompleteTextView I did it with a listView, with the same process, and everything worked well.
Any ideas or solutions would be really appreciated
EDIT : I noticed something really strange : the data is not binded to the adapter, because adapter#getCount always returns 0, even if the list is not empty. But when I remove at_address.setAdapter(addressAdapter), the data adapter is updated and adapter#getCount returns the right number of elements.
I am really confused right now, please help !
Instead of this:
for(int i = 0;i<data.size();i++){
suggestions_address.add(data.get(i));
}
you can use just this:
suggestions_address.addAll(data);
you are calling notifyDataSetChanged after you start the request, you should call it after you get the result and update the suggestions_address, so call notifyDataSetChanged inside onCompleted
i'm having an issue that soon enough going to blow me.
i have Database table lets call it A. table A has field that determines if this row is processed or no. i update the field myself from within the Parse Browser to either True | False, and trying to call query.findInBackground() to check with the Boolean value however the returned List always returns False if its True and vice versa. enough talking let me show you what i'm doing.
public static void getMyRequests(ParseUser user, final FindCallback<ServicesModel> callback) {
ParseQuery<ServicesModel> query = new ParseQuery<>(ServicesModel.class);
if (!user.getBoolean(ParseHelper.CAN_UPLOAD)) {
query.whereEqualTo("user", user);
}
query.findInBackground(new FindCallback<ServicesModel>() {
#Override public void done(final List<ServicesModel> objects, ParseException e) {
if (e == null) {
if (objects != null && !objects.isEmpty()) {
for (ServicesModel object : objects) {
object.setHandlerUser(object.getParseUser("handlerUser"));
object.setProcessedTime(object.getLong("processedTime"));
object.setCategoryType(object.getString("categoryType"));
object.setUser(object.getParseUser("user"));
object.setUserRequest(object.getString("userRequest"));
object.setImageUrl(object.getString("imageUrl"));
object.setProcessed(object.getBoolean("isProcessed"));
Logger.e(object.getBoolean("isProcessed") + "");
}
callback.done(objects, null);
} else {
callback.done(null, new ParseException(1001, "No Services"));
}
} else {
callback.done(null, e);
}
}
});
}
the code above suppose to refresh my data but however my log always shows that isProcessed is False even tho it's set to True inside the Parse Browser
what i have tried besides this? fetchAllInBackground & fetch() you name it. the object will always return false until i re-run the application from Android Studio what i'm doing here wrong? btw here is how i initialize Parse
Parse.setLogLevel(BuildConfig.DEBUG ? DEBUG_LEVEL : Parse.LOG_LEVEL_NONE);
ParseObject.registerSubclass(ProductsModel.class);
ParseObject.registerSubclass(ProductRentalModel.class);
ParseObject.registerSubclass(ServicesModel.class);
Parse.enableLocalDatastore(context);
Parse.initialize(context, context.getString(R.string.app_id), context.getString(R.string.client_id));
the answer was to remove
Parse.enableLocalDatastore(context);
which is bad anyway, without the datastore enabled the data are refreshed probably, however with enabling the local database, the data will not refresh unless if i killed the app and/or re-install it. that's bad. but did the trick.
I'm developing an Android Mobile Application and one of the most important functionality of the app itself is being able to talk with a third-party API Service.
The third party service, offering these API, wants a "beacon" to be included into every API request i made.
The "beacon" is a "long integer" and it must be unique and incremental for every request.
The problem is:
I'm firing a couple of these request and i do not know which of these requests will complete first so i'm running into a race condition: where the second request ends quickly before the first request invalidating the first request!
When a button is clicked the following action will be executed:
public void fireRequests(View view)
{
long first_beacon = System.nanoTime();
fireFirstRequest(view, first_beacon);
long second_beacon = System.nanoTime();
fireSecondRequest(view, second_beacon);
}
I'm using Volley in a proper way, setting up callback etc.. example here:
fireFirstRequest method:
public void fireFirstRequest(View view, long beacon)
{
final ThirdPartyLib api_lib = new ThirdPartyLib(getActivity());
api_lib.doOperationA(beacon, new ThirdPartyLib.MyOwnCallback()
{
#Override
public void update(JSONObject jsonObject)
{
try
{
JSONObject result = jsonObject.getJSONObject("response");
/* my code */
Log.d("doOperationA", result)
}
catch (JSONException e)
{
e.printStackTrace();
}
}
});
}
fireSecondRequest method:
public void fireSecondRequest(View view, long beacon)
{
final ThirdPartyLib api_lib = new ThirdPartyLib(getActivity());
api_lib.doOperationB(beacon, new ThirdPartyLib.MyOwnCallback()
{
#Override
public void update(JSONObject jsonObject)
{
try
{
JSONObject result = jsonObject.getJSONObject("response");
/* my code */
Log.d("doOperationB", result)
}
catch (JSONException e)
{
e.printStackTrace();
}
}
});
}
Here is the execution log:
03-12 14:26:56.252 18769-18769/it.example.app D/Volley: queued doOperationA
03-12 14:26:58.124 18769-18769/it.example.app D/Volley: queued doOperationB
03-12 14:26:59.433 18769-18769/it.example.app D/App: doOperationB: {
"error": false,
"payload": {
"foo": "bar"
}
}
03-12 14:27:04.181 18769-18769/it.example.app D/App: doOperationA: {
"error": true,
"errorMessage": "invalid beacon"
"payload": {}
}
The question is: what's the best way to keep track of beacon before firing an API request or to maintain a "execution order" separation even if we are talking of ASync request?
My rough solution is to call the fireSecondRequest() inside the callback of the fireFirstRequest() when i'm completely sure that first request is done.
I know, this is the best way to kill the awesome world of async requests.
modified action:
public void fireRequests(View view)
{
long first_beacon = System.nanoTime();
fireFirstRequest(view, first_beacon);
}
fireFirstRequest modified method with final View parameter:
public void fireFirstRequest(final View view, long beacon)
{
final ThirdPartyLib api_lib = new ThirdPartyLib(getActivity());
api_lib.doOperationA(beacon, new ThirdPartyLib.MyOwnCallback()
{
#Override
public void update(JSONObject jsonObject)
{
try
{
JSONObject result = jsonObject.getJSONObject("response");
/* my code */
Log.d("doOperationA", result)
/* fire second request */
// EDIT
fireSecondRequest(view, System.nanoTime());
}
catch (JSONException e)
{
e.printStackTrace();
}
}
});
}
You didn't add the part of your code which initiates the Volley RequestQueue, but I'm assuming you're creating the default way using:
RequestQueue requestQueue = Volley.newRequestQueue(context, stack);
When you do this, you get a request queue which allows for 4 concurrent requests by default. You can see this by looking at the constructor this method uses to create a request queue:
private static final int DEFAULT_NETWORK_THREAD_POOL_SIZE = 4;
...
public RequestQueue(Cache cache, Network network) {
this(cache, network, DEFAULT_NETWORK_THREAD_POOL_SIZE);
}
You can overcome this issue if instead of using the default method for creating a RequestQueue, you create your own RequestQueue with a thread pool size of 1. This way, there can be no 2 concurrent requests, and requests will be sent in the order they are dispatched.
The downside with this, of course, is that this can dramatically slow down your app. If all requests must wait until the previous request is finished, this creates a serious bottleneck in your app.
Perhaps consider using more than 1 request queue, and only use this special request queue for requests that rely on this special constraint.
Hope this helps.
I'm using 'Retrofit' for making asynchronous network requests, how might i right a function for handling logins? For instance i've currently attempted:
public UserAuthResponse Login(String username, String password) {
try {
Callback<UserAuthResponse> getAuthCallback = new Callback<UserAuthResponse>() {
#Override
public void failure(RetrofitError arg0) {
if (arg0 != null) {
if (arg0.getMessage() != null
&& arg0.getMessage().length() > 0) {
Log.e("KFF-Retrofit", arg0.getMessage());
}
}
}
#Override
public void success(UserAuthResponse listItem,
retrofit.client.Response arg1) {
Log.e("dg", listItem.getUser().getFirstname());
}
};
service.authUser(username, MD5(password), getAuthCallback);
return response;
} catch (RetrofitError e) {
e.printStackTrace();
return null;
}
}
But this is flawed: there is no way of returning the 'UserAuthResponse' from the function? How can i pass back the result?
It seems like i need a synchronous call to the web service but then i'm hit with a 'NetworkOnMainThreadException'
What is the best practice for things like this? Sorry about the poor explanation, struggling to form the right words.
Well the things is that when you're using the Callback as your means of getting the results from Retrofit you automatically giving away the possibility of having the response returned inline. There's a few ways this can be solved. I suppose it's up to you to choose which one fits best with your design.
You could decide to not use the Callback approach and use the inline result from Retrofit but then you'd need to handle the scheduling yourself otherwise you'll hit the Exception of NetworkOnMainThreadException like you mentioned.
You could also pass in a listener to your login method. This listener could then be called by the result Callback. This could be useful if you're trying to hide Retrofit behind some sort of service layer and expose a simple login interface.
interface OnLoginListener {
onLoginSuccessful(UserAuthResponse response);
onLoginFailed(Throwable t);
}
public void Login(String username, String password, final OnLoginListener listener) {
Callback<UserAuthResponse> getAuthCallback = new Callback<UserAuthResponse>() {
#Override
public void failure(RetrofitError e) {
// You can handle Retrofit exception or simply pass them down to the listener as is
listener.onLoginFailed(e);
}
#Override
public void success(UserAuthResponse listItem,
retrofit.client.Response arg1) {
// handle successful case here and pass down the data to the listener
listener.onLoginSucessful(listItem);
}
};
service.authUser(username, MD5(password), getAuthCallback);
}
use this line i Manifest
<uses-permission android:name="android.permission.INTERNET"/>
or use this before network operation (not suggestible)
if (Build.VERSION.SDK_INT>= 10) {
ThreadPolicy tp = ThreadPolicy.LAX;
StrictMode.setThreadPolicy(tp);
}
I have a problem with synchronizing results from AsyncTask when needed to check if input is vaild.
My application asks user to type in some promotion code into EditText. I want to label promotion code as valid if promotion code is in database. If promotion code entered is not in database, it is labeled as invalid.
This is code for button listener
// Listens for Add button presses
addButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
String promo_code = (String) PromotCodeEditText.getText().toString();
// Start AsyncTask that will store true or false in checkCodeInDatabase variable
// depending if PromoCode is in database. We use checkCodeInDatabase in else if check below.
new CheckCodeDatabase().execute(promo_code);
// Check if Promo Code that user typed is in database
// checkCodeInDatabase is false if course is not in database
if (!checkCodeInDatabase) {
// Display No code in database alert dialog
showMsgDialog(getString(R.string.noCodeDBTitle),
getString(R.string.noCodeDBMessage));
courseCodeEditText.setText("");
} else {
// Add promo code user typed in EditText
addCode(promo_code);
}
}
});
My idea is that when user presses ADD button, to add promo code, I start AsyncTask which performs a query on database. AsyncTask stores true or false in static variable checkCodeInDatabase.
Here's code for AsyncTask:
private class CheckCodeDatabase extends AsyncTask<String, Object, Boolean> {
DataBaseHelper myDbHelper = new DataBaseHelper(MainActivity.this);
#Override
protected Boolean doInBackground(String... params)
{
try {
myDbHelper.createDataBase();
} catch (IOException ioe) {
throw new Error("Unable to create database");
}
try {
myDbHelper.openDataBase();
} catch (SQLException sqle) {
throw sqle;
}
// This returns true or false if params[0], which is a promo code,
// is in in PromoCodes table in database.
return myDbHelper.checkCourseInDatabase(params[0]);
}
#Override
protected void onPostExecute(Boolean result) {
// Store true or false in checkCodeInDatabase which is a static variable.
// This variable will be used to check if code is valid in add button listener.
checkCodeInDatabase = result;
myDbHelper.close();
}
Problem:
Problem is that AsyncTask does not store value into checkCodeInDatabase variable on time. Meaning, if statement which is performed in add button listener, value of checkCodeInDatabase is the old value because AsyncTask does not have enough time to perform database query and update checkCodeInDatabase variable before if statement is executed in add button listener.
So, how to make add button listener wait for AsyncTask to update checkCodeInDatabase and then perform if check.
Thanks in advance!
p.s. I'm new to android development. I read in some book on Android development that any queries on database should be performed in AsyncTasks, to avoid unresponsive app. Maybe it's impossible to achieve what I want with AsyncTasks. Any suggestions are welcome.
You should delegate the whole
if (!checkCodeInDatabase) {
// Display No code in database alert dialog
showMsgDialog(getString(R.string.noCodeDBTitle),
getString(R.string.noCodeDBMessage));
courseCodeEditText.setText("");
} else {
// Add promo code user typed in EditText
addCode(promo_code);
}
block into you AsyncTask's onPostExecute.
Doing that you are sure that you have fetched the result AND that you are running on the ui thread.