Develop Reference

Wait for Database to finish inserting data before continuing to next activity Android

I have an activity that calls JSON data from a foreign database.
Below is my ideal case for my app:
The JSON data is parsed and inserted into an SQLite database on Android
Next activity is started and the newly inserted data is read from the SQLite database
What actually happens:
The JSON data is parsed and inserted into an SQLite database on Android
The next activity is started while data is still being inserted and returns zero when reading from the desired databse for my ListArray in that activity.
How do I force Android to wait until database insertion is completed before starting the next activity?
EDIT
My doInBackground looks as follows:
#Override
protected String doInBackground(String... params) {
StringRequest strReq = new StringRequest(Request.Method.GET,
str, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
try {
JSONObject jObj = new JSONObject(response);
boolean error = jObj.getBoolean("error");
// Check for error node in json
if (!error) {
JSONArray jObjInside = jObj.getJSONArray("service_prov_services");
for (int i = 0; i < jObjInside.length(); i++) {
// Now store the user in SQLite
try {
// JSONObject user = jObj.getJSONObject("user");
String service_prov_type = jObj.getString("service_prov_type");
String service_prov_name = jObj.getString("service_prov_name");
String addr_street = jObj.getString("addr_street");
String addr_num = jObj.getString("addr_number");
String addr_plz = jObj.getString("addr_plz");
String addr_city = jObj.getString("addr_city");
JSONObject elem = jObjInside.getJSONObject(i);
if(elem != null){
String service_id = elem.getString("service_id");
String service_type = elem.getString("service_type");
String service_measure = elem.getString("service_measure");
// Inserting row in userServiceProvServices table
db.addUserServiceProvServices(service_id, service_prov_type,
service_prov_name, addr_street, addr_num, addr_plz, addr_city, service_type, service_measure);
Log.d("post_url for service", addr_plz );
}
} catch (JSONException e) {
// JSON error
e.printStackTrace();
Toast.makeText(getActivity().getApplicationContext(), "Json error: " +
e.getMessage(), Toast.LENGTH_LONG).show();
}
}
} else {
// Error in login. Get the error message
String errorMsg = jObj.getString("error_msg");
Toast.makeText(getActivity().getApplicationContext(),
errorMsg, Toast.LENGTH_LONG).show();
}
} catch (JSONException e) {
// JSON error
e.printStackTrace();
Toast.makeText(getActivity().getApplicationContext(), "Json error: " +
e.getMessage(), Toast.LENGTH_LONG).show();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e(TAG, "Login Error: " + error.getMessage());
Toast.makeText(getActivity().getApplicationContext(),
error.getMessage(), Toast.LENGTH_LONG).show();
}
});
Log.d("test string to appcntr",strReq.toString());
// Adding request to request queue
AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
return params[0];
}
onPostExecute looks as follows:
#Override
protected void onPostExecute(String Result) {
//super.onPostExecute(Result);
pdLoading.dismiss();
//this method will be running on UI thread
Log.d(TAG, "Stamp: " + Result);
Bundle args = new Bundle();
args.putString("stampID", Result);
ProviderServiceListFragment frag = new ProviderServiceListFragment();
frag.setArguments(args);
FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.content_frame,
frag)
.commit();
}
With the way I am doing it now, my next Fragment is already called, although the data has not finished being entered into the database. This means the ListArray in the follwoing Fragment is empty because of the missing database data.

I worked on this for a month and finally figured it out for myself (stupid nube I am..) So here is a piece of code inserting a record to sqlite.
On the chosen event ("onClick actionbutton1") a new AsyncTask is created with doInBackground, onPreExecute and onPostExecute.
onPreExecute will setMessage() and show() the progressDialog which will start spinning
onPostExecute will handle the new/next Activity
READ BELOW FOR doInBackground!!
actionButton1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
final ProgressDialog progressDialog = new ProgressDialog(AddUpdateEvf.this);
new AsyncTask<Void, Void, Boolean>() {
protected Boolean doInBackground(Void... params) {
doOneThing();
return null;
}
#Override
protected void onPreExecute() {
progressDialog.setMessage("Processing...");
progressDialog.show();
}
protected void onPostExecute(Boolean result) {
evaluationFormOps.close();
progressDialog.dismiss();
AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(AddUpdateEvf.this);
alertDialogBuilder.setMessage("Added to Database...")
.setCancelable(false)
.setPositiveButton("Continue", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
i = new Intent(AddUpdateEvf.this, ViewProduct.class);
i.putExtra(EXTRA_ADD_UPDATE, "View");
i.putExtra(EXTRA_PRODUCT_ID, hiddenTextId.getText().toString());
i.putExtra(EXTRA_PRODUCT_NO, productNo_tv.toString());
startActivity(i);
dialog.dismiss();
finish();
}
});
AlertDialog alert = alertDialogBuilder.create();
alert.show();
}
private void doOneThing() {
makeDbRequest();
do {
evfId = newEvf.getEvfId();
}
while (evfId<1);
}
}.execute();
}
});
Note this snippet in the above code called in doInBackground():
private void doOneThing() {
makeDbRequest();
do {
evfId = newEvf.getEvfId();
}
while (evfId<1);
}
Note: The makeDbRequest() handles the insert to sqlite by setting the values and then passing it to another class which handles the cursor and puts the values etc.
Heres a small snippet of relevant code in that class (which you should already have mastered...):
public Evf addEvf(Evf evf, String dBsuccess){
ContentValues values = new ContentValues();
values.put(TableHelper.PRODUCT_IDE,evf.getPRODUCTId());
values.put(TableHelper.CSCORE,evf.getcScore());
values.put(TableHelper.FSCORE,evf.getfScore());
values.put(TableHelper.TSCORE,evf.gettScore());
values.put(TableHelper.WEIGHT,evf.getWeight());
values.put(TableHelper.TEMP,evf.getTemp());
values.put(TableHelper.STATUS,evf.getStatus());
values.put(TableHelper.TIMESTAMP, String.valueOf(evf.getTimeStamp()));
values.put(TableHelper.LOADED, dBsuccess);
long insertid = database.insert(TableHelper.TABLE_EVFS,null,values);
evf.setEvfId((int) insertid);
return evf;
}
So above you can see the Id of, in my case evaluationform(Evf), being set to the insert id. This happens after the insert and you can set any value in your object class (the one with getters and setters...Evf())
Finally, use the do...while statement above to "listen" for the value being set in the object class
This can obviously only happen if the insert was finished and the onPosteExecute takes care of the rest
Hope it helps, crit is welcome, PEACHES!!

Use AsyncTask to process the Database insertion process & then use the onPostExecute method to move away from the current activity.
private class ProcessDatabase extends AsyncTask<String, String, String> {
String sampleData;
#Override
protected String doInBackground(String... params) {
//Call your Database Insert method here.
//In this example, I am inserting sampleData to the DB
return null;
}
#Override
protected void onPostExecute(String result) {
//This gets triggered when the process is complete
}
}
You can start the AsyncTask by adding the following code in your onCreate or where ever you want to start the DB Insertion process:
//in this case I am just passing a string, You can create your own
//custom class & send that as well
ProcessDatabase.execute(myData);
Refer this link for more information. Good luck!

The StringRequest is an Asynchronous request, so upon the executing the those lines onPostExecute will called immediately, so there is no guarantee that the sql update will complete before the next activity is launched.
Call the nextActivity at the end of the onResponse callback method of the StringRequest which way you can guarantee to insert the data to db first and then call the nextActivity.
private void makeJsonRequest(String str) {
StringRequest strReq = new StringRequest(Request.Method.GET,
str, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
try {
JSONObject jObj = new JSONObject(response);
boolean error = jObj.getBoolean("error");
// Check for error node in json
if (!error) {
JSONArray jObjInside = jObj.getJSONArray("service_prov_services");
for (int i = 0; i < jObjInside.length(); i++) {
// Now store the user in SQLite
try {
// JSONObject user = jObj.getJSONObject("user");
String service_prov_type = jObj.getString("service_prov_type");
String service_prov_name = jObj.getString("service_prov_name");
String addr_street = jObj.getString("addr_street");
String addr_num = jObj.getString("addr_number");
String addr_plz = jObj.getString("addr_plz");
String addr_city = jObj.getString("addr_city");
JSONObject elem = jObjInside.getJSONObject(i);
if (elem != null) {
String service_id = elem.getString("service_id");
String service_type = elem.getString("service_type");
String service_measure = elem.getString("service_measure");
// Inserting row in userServiceProvServices table
db.addUserServiceProvServices(service_id, service_prov_type,
service_prov_name, addr_street, addr_num, addr_plz, addr_city, service_type, service_measure);
Log.d("post_url for service", addr_plz);
}
} catch (JSONException e) {
// JSON error
e.printStackTrace();
Toast.makeText(getActivity().getApplicationContext(), "Json error: " +
e.getMessage(), Toast.LENGTH_LONG).show();
}
}
goNextActivity();
} else {
// Error in login. Get the error message
String errorMsg = jObj.getString("error_msg");
Toast.makeText(getActivity().getApplicationContext(),
errorMsg, Toast.LENGTH_LONG).show();
}
} catch (JSONException e) {
// JSON error
e.printStackTrace();
Toast.makeText(getActivity().getApplicationContext(), "Json error: " +
e.getMessage(), Toast.LENGTH_LONG).show();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e(TAG, "Login Error: " + error.getMessage());
Toast.makeText(getActivity().getApplicationContext(),
error.getMessage(), Toast.LENGTH_LONG).show();
}
});
Log.d("test string to appcntr", strReq.toString());
// Adding request to request queue
AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
}
private void goNextActivity(){
//this method will be running on UI thread
ProviderServiceListFragment frag = new ProviderServiceListFragment();
frag.setArguments(args);
FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.content_frame,
frag)
.commit();
}

AsyncTask return a boolean while retrieving information from a Json

I want to check if a user is registered or not in a database, and if it is get the information of the user.
Normally, when I retrieve the information from the server, I put in the Json a variable saying if the user exists or not. Then in onPostExecute(Void result) i treat the Json, so i don't need the AsyncTask to return any value.
Before I was calling the AsyncTask as follows:
task=new isCollectorRegistered();
task.execute();
But now i'm trying a different approach. I want my asynktask to just return a boolean where i called the AsyncTask.
the AsyncTask looks as follows:
public class isCollectorRegistered extends AsyncTask<Void, Void, Void> {
private static final String TAG_SUCCESS = "success";
int TAG_SUCCESS1;
private static final String TAG_COLLECTOR = "collector";
public String collector;
JSONArray USER = null;
JSONObject jObj = null;
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected Void doInBackground(Void... params) {
// Checks on the server if collector is registered
try {
jObj = ServerUtilities.UserRegistered(context, collector);
return null;
} finally {
return null;
}
}
#Override
protected void onPostExecute(Void result) {
try {
String success = jObj.getString(TAG_SUCCESS);
Log.d(TAG_COLLECTOR, "Final Info: " + success);
//This if sees if user correct
if (Objects.equals(success, "1")){
//GOOD! THE COLLECTOR EXISTS!!
}
} catch (JSONException e) {
e.printStackTrace();
Log.d(TAG_COLLECTOR, "JSON parsing didn't work");
}
}
}
I have checked several posts, but I still havent found out the way to retrieve the boolean where I call the Asynktask, something like this :
task=new isCollectorRegistered();
task.execute();
boolean UserRegistered = task.result();
What would be the right approach? Any help would be appreciated

To use AsyncTask you must subclass it. AsyncTask uses generics and varargs. The parameters are the following AsyncTask <TypeOfVarArgParams , ProgressValue , ResultValue> .
An AsyncTask is started via the execute() method.
The execute() method calls the doInBackground() and the onPostExecute() method.
TypeOfVarArgParams is passed into the doInBackground() method as input, ProgressValue is used for progress information and ResultValue must be returned from doInBackground() method and is passed to onPostExecute() as a parameter.
In your case you are passing Void to your AsyncTask : isCollectorRegistered extends AsyncTask<Void, Void, Void> so you can't get your result from the thread.
please read this tutorial to a deep understand of the AsyncTask in Android

I think the following is exactly what you were looking for, Alvaro...NOTE: I tweaked your code to make it more sensible, but I tried to stick to as much of your original code as possible...
public class RegisterCollector extends AsyncTask<String, Void, Boolean> {
private static final String TAG_SUCCESS = "success";
private static final String TAG_COLLECTOR = "collector";
int TAG_SUCCESS1;
String[] strArray;
JSONArray USER = null;
JSONObject jObj = null;
public String collector;
private AppCompatActivity mAct; // Just incase you need an Activity Context inside your AsyncTask...
private ProgressDialog progDial;
// Pass data to the AsyncTask class via constructor -> HACK!!
// This is a HACK because you are apparently only suppose to pass data to AsyncTask via the 'execute()' method.
public RegisterCollector (AppCompatActivity mAct, String[] strArray) {
this.mAct = mAct;
this.strArray = strArray;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
// AHAH!! - So we do need that Activity Context after all...*TISK* *TISK* # Google **sigh**.
progDial = ProgressDialog.show(mAct, "Please wait...", "Fetching the strawberries & cream", true, false);
}
#Override
protected Boolean doInBackground(String... params) {
// Checks on the server if collector is registered
try {
jObj = ServerUtilities.UserRegistered(context, collector);
return true; // return whatever Boolean you require here.
} finally {
return false; // return whatever Boolean you require here.
}
}
#Override
protected void onPostExecute(Boolean result) {
super.onPostExecute(result);
progDial.dismiss();
try {
String success = jObj.getString(TAG_SUCCESS);
Log.d(TAG_COLLECTOR, "Final Info: " + success);
// This 'if' block checks if the user is correct...
if (Objects.equals(success, "1")){
//GOOD! THE COLLECTOR EXISTS!!
}
// You can then also use the Boolean result here if you need to...
if (result) {
// GOOD! THE COLLECTOR EXISTS!!
} else {
// Oh my --> We need to try again!! :(
}
} catch (JSONException e) {
e.printStackTrace();
Log.d(TAG_COLLECTOR, "JSON parsing didn't work");
Toast.makeText(mAct, "JSON parsing FAILED - Please try again.", Toast.LENGTH_LONG).show();
}
}
}
...then if you want to use the generated Boolean data outside the AsyncTask class try the following:.
RegisterCollector regisColctr = new RegisterCollector((AppCompatActivity) this, String[] myStrArry);
AsyncTask<String, Void, Boolean> exeRegisColctr = regisColctr.execute("");
Boolean isColctrRegistered = false;
try {
isColctrRegistered = exeRegisColctr.get(); // This is how you FINALLY 'get' the Boolean data outside the AsyncTask...-> VERY IMPORTANT!!
} catch (InterruptedException in) {
in.printStackTrace();
} catch (ExecutionException ex) {
ex.printStackTrace();
}
if (isColctrRegistered) {
// Do whatever tasks you need to do here based on the positive (i.e. 'true') AsyncTask Bool result...
} else {
// Do whatever tasks you need to do here based on the negative (i.e. 'false') AsyncTask Bool result...
}
There you go - I think this is what you were looking for (originally). I always use this approach whenever I need Async data externally, and it has yet to fail me....

How to Handle networkonmainthreadexception in Android?

I have following 2 class
class CallNetworkMethod extends AsyncTask<Void, Void, Void>
{
#Override
protected Void doInBackground(Void... params) {
if (TwitterUtils.isAuthenticated(prefs)) {
sendTweet();
} else {
Intent i = new Intent(getApplicationContext(), TwPrepareRequestTokenActivity.class);
i.putExtra("tweet_msg",getTweetMsg());
startActivity(i);
}
return null;
}
#Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
//updateLoginStatus();
loginStatus.setText("Logged into Twitter : " + TwitterUtils.isAuthenticated(prefs));
}
}
====================================================
public class TwitterUtils {
static ArrayList<String> friens=null;
public static boolean isAuthenticated(SharedPreferences prefs) {
String token = prefs.getString(OAuth.OAUTH_TOKEN, "");
String secret = prefs.getString(OAuth.OAUTH_TOKEN_SECRET, "");
AccessToken a = new AccessToken(token,secret);
Twitter twitter = new TwitterFactory().getInstance();
twitter.setOAuthConsumer(TwConstants.CONSUMER_KEY, TwConstants.CONSUMER_SECRET);
twitter.setOAuthAccessToken(a);
try {
**twitter.getAccountSettings();**
return true;
} catch (TwitterException e) {
return false;
}
}
}
I got the exception when running this code(networkonmainthreadexception).I debug this code and found the location where exception come out. It is twitter.getAccountSettings(); .I think this method should run inside a AsynTask but i dont know how to do that.

Currently you are calling TwitterUtils.isAuthenticated(prefs) in onPostExecute because onPostExecute always execute on UI thread then you are getting networkonmainthreadexception exception .
to avoid this issue use a Boolean Flag to get return from doInBackground and show it in TextView in onPostExecute as:
class CallNetworkMethod extends AsyncTask<Void, Void, Void>
{
public static boolean status=false;
#Override
protected Void doInBackground(Void... params) {
status=TwitterUtils.isAuthenticated(prefs);
return null;
}
#Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
//updateLoginStatus();
loginStatus.setText("Logged into Twitter : " + status);
}
}

the problem is that you're using the AsyncTask wrong.
The idea for the onBackground returning a value and the onPostExecute receiving a result is to pass to the UI thread something that was done on the background thread.
Something like that:
change the class CallNetworkMethod extends AsyncTask<Void, Void, Void> to
class CallNetworkMethod extends AsyncTask<Void, Void, Boolean>
change the protected Void doInBackground(Void... params) { to
protected Boolean doInBackground(Void... params) {
Boolean result = TwitterUtils.isAuthenticated(prefs);
if (result) {
sendTweet();
} else {
Intent i = new Intent(getApplicationContext(), TwPrepareRequestTokenActivity.class);
i.putExtra("tweet_msg",getTweetMsg());
startActivity(i);
}
return result;
}
and change the protected void onPostExecute(Void result) { to
protected void onPostExecute(Boolean result) {
loginStatus.setText("Logged into Twitter : " + result.toString());
}

Note that this method blocks waiting for a network response, so do not call it in a UI thread.
This is what is suggested when using:
facebook.request("me");
Same might be the case with:
twitter.getAccountSettings();
So, just like other Network connections, which you call using AsyncTasks, call this in some AsyncTask.
Okay, the Error might be here:
#Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
//updateLoginStatus();
loginStatus.setText("Logged into Twitter : " + TwitterUtils.isAuthenticated(prefs));
}
You are calling TwitterUtils.isAuthenticated(prefs) in onPostExecute();

Your first call to isAuthenticated() is correctly placed in the AsyncTask. However, when you use:
loginStatus.setText("Logged into Twitter : " + TwitterUtils.isAuthenticated(prefs));
in your onPostExecute(), you're calling a networking method on the UI thread again, as onPostExecute() is run on the UI thread.
Remove this line, or store the result locally from doInBackground() and use it here.

android AsyncTask - can't execute onPostExecute method

I have wrote an app to run an AsyncTask and part of the code is listed as follow. The problem is when the AsyncTask start by execute the code - "new AddImageTask().execute();" in the thread handler, the task will start and everything seems right. However, eventually the app will stay in "doInBackground" method after all code in "doInBackground" method has been executed. The task can't go to "onPostExecute" method. (i.e. can't dismiss the dialog...) What get wrong?
Thanks for the help......
private Handler handleFetchResult = new Handler() {
#Override
public void handleMessage(Message msg) {
progressDialog.dismiss();
Log.d(TAG, "Start handle fetch result");
try {
JSONArray ja = new JSONArray(fetchResult);
Log.d(TAG, "JSON Array Length = " + ja.length());
JSONObject jo = new JSONObject();
for (int i = 0; i < ja.length(); i++) {
jo = ja.getJSONObject(i);
PhotoURLs.add(PAT_url + jo.getString("filePath"));
Log.d(TAG, PhotoURLs.get(i));
}
} catch (JSONException e) {
Log.d(TAG, "Fetch result error: " + e.getLocalizedMessage());
e.printStackTrace();
}
//TODO: display thumbnail
new AddImageTask().execute();
}//void handleMessage
};//Handler handleFetchResult
class AddImageTask extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
loadThumbnailDialog.show(SitePhotoGallery.this, "Fetch thumbnails from server",
"Loading...", true, true);
Log.d("AddImageTask.onPreExecute","onPreExecute");
}
#Override
protected Void doInBackground(Void... unused) {
// TODO Auto-generated method stub
for (String url : PhotoURLs) {
String filename = url.substring(url.lastIndexOf("/") + 1, url.length());
String thumburl = url.substring(0, url.lastIndexOf("/")+1);
imgAdapter.addItem(LoadThumbnailFromURL(thumburl + filename));
publishProgress();
}
Log.d("AddImageTask.doInBackground","doInBackground");
return null ;
}
#Override
protected void onProgressUpdate(Void... unused) {
super.onProgressUpdate();
imgAdapter.notifyDataSetChanged();
Log.d("AddImageTask.onProgressUpdate","OnProgressUpdate");
}
protected void onPostExecute(Void... unused) {
super.onPostExecute(null);
loadThumbnailDialog.dismiss();
Log.d("AddImageTask.onPostExecute","onPostExecute");
}
}

I think it's because onPostExecute() should take a Void parameter and not a Void... parameter. (You should also specify #Override as Soxxeh pointed out in his/her comment above.)

AsyncTask and JSOUP Parsing

so basically im trying to parse some data from website using AsyncTask, i want it to get website url from program, update ui with downloaded data and show progressdialog (spinning wheel) so i figured i need to do it like that: (UPDATE): k now its ok with variables but program force closes anyway
private class backgroundDATA extends AsyncTask<String, Void, Void> {
ProgressDialog dialog;
Document doc;
#Override
protected void onPreExecute() {
dialog = dialog.show(Result.this, " ",
" Loading. Please wait ... ", true);
}
#Override
protected Void doInBackground(String... params) {
try {
doc = Jsoup.connect(params[0]).get();
} catch (IOException e){
e.printStackTrace();
}
return null;
}
protected void onPostExecute(Void result) {
Elements maine;
Elements titleJSOUP;
Elements recipeJSOUP;
Elements instructionsJSOUP;
String recipE;
maine = doc.select("div#recipeContent");
titleJSOUP = doc.select("title");
recipeJSOUP = maine.select("ul.recipe");
instructionsJSOUP = maine.select("p.instructions");
recipE = recipeJSOUP.toString();
drinkNameText.setText("THE "
+ Jsoup.parse(titleJSOUP.toString()).text()
);
dontListenText.setText(Jsoup.parse(titleJSOUP.toString()).text()
);
recipeText.setText(prepareDRINK(recipE));
instructionsText.setText(Jsoup.parse(instructionsJSOUP.toString())
.text());
dialog.dismiss();
}
}

Well this is going to cause a NullPointerException for a start...
#Override
protected void onPreExecute() {
dialog = dialog.show(Result.this, " ",
" Loading. Please wait ... ", true);
}
You can't call dialog.show(...) as dialog will be null.
Call the static ProgressDialog.show(...) method instead.