Hello i'm developing an application that performs database queries on a remote server. so far i've successfully interacted with the PHP script on the server side and my code is sending string values without a problem, but i'm not sure how to check if i'm recieving back the values i'm sending back through my PHP script, as my OnPostExecute function is not responding.
Please Help.
Here's the code that's facing problem :
public void submit_data(View V){
try{
new DoSocketProgramming().execute("10.0.2.2");
}
catch(Exception e){
Toast.makeText(getApplicationContext(), "problem here", Toast.LENGTH_SHORT).show();
}
Toast.makeText(getApplicationContext(), "created till here", Toast.LENGTH_SHORT).show();
}
public class DoSocketProgramming extends AsyncTask<String, Void, String>
{
String sendsentence=" this message is sent\n";
String recvsentence=null;
protected void onPreExecute()
{
Toast.makeText(getApplicationContext(), "this is preExecute", Toast.LENGTH_LONG).show();
}
#Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
try{
Socket con=new Socket(addr,1678);
DataInputStream dis=new DataInputStream(con.getInputStream());
DataOutputStream dos=new DataOutputStream(con.getOutputStream());
dos.writeUTF(sendsentence);
recvsentence=dis.readUTF();
}catch(Exception e){
e.printStackTrace();
}
return recvsentence;
}
protected void onPostExecute(String result) {
try{
Toast.makeText(getApplicationContext(), "this is post execute"+ recvsentence, Toast.LENGTH_LONG).show();
}catch(Exception e){
e.printStackTrace();
}
}
}
It probably is, actually. The problem is that you're using getApplicationContext() as the Context and this is almost always wrong, you shouldn't use this unless you know exactly what you're doing.
When creating an AsyncTask, the constructor receives the Context of the Activity that invoked it, you should store this Context in your AsyncTask class and use it in your onPostExecute() method.
This would be an example:
public class MyAsyncTask extends AsyncTask {
Context context;
private MyAsyncTask(Context context) { this.context = context; }
#Override
protected void onPostExecute(...) {
super.onPostExecute(result);
Toast.makeText(context, "this is post execute"+ recvsentence, Toast.LENGTH_LONG).show();
}
}
Related
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....
I am writing here because this is my last solution of understanding this type of programming.The problem is that I got stuck on what to use to handle the connection to a server and log-in. Should I use async task, handler or thread ? I didn't find a concrete answer stating which one to use, only found that async task is used to download images or other download stuffs.
Until now I have used a thread to connect to the server. The problem I encountered was when I catch the exception ( Putting invalid username/password ) and try to log-in again. ( I needed to "close" the last thread and start one again )
After this I started to use async task but I don't really understand how it should work and I am stuck on a toast of invalid username/password.
private class connectStorage extends AsyncTask<Void, Void, Void> {
#Override
protected Void doInBackground(Void... params) {
try {
api = DefaultClientFactory.create(host, getUser, getPassword);
if (api.getAuthToken().trim().length() > 3) {
//TO DO LAYOUT CHANGE;
}
} catch (StorageApiException e) {
e.printStackTrace();
Log.i("TEST", "" + e.getMessage());
}
return null;
}
Also, I am 100% sure that calling inflate in the doInBackground method won't work too ( there I wanted to change the activity ).
I am starting the async task on a button press.
When you are using asynctask
You have doInBackground and onPostExecute
So basically get a json or string or boolean as a result from doinbackground
and in onpostexecute check if the login in succesful or not if its succesful save the data from server and start an intent to go to another activity or toast the user that that user login details are wrong and try again.
So your asynctask can be an inner class of your activity class which is login and onClickSubmit button call the asynctask class and on post execute parse the json and according to the result decide what to do
Example:
public class SignInAsycTask extends AsyncTask<RequestParams, Void, String> {
#Override
protected String doInBackground(RequestParams... params) {
return new HttpManager().sendUserData(params[0]);
}
#Override
protected void onPostExecute(String result) {
String[] details = parseJsonObject(result);
if (details != null) {
user.setUser_id(Integer.valueOf(details[0]));
user.setName(details[1]);
if (details.length > 2) {
user.setProfilePic(details[2]);
}
setSharedPreferences();
startActivity(new Intent(Signin.this, MainActivity.class));
finish();
} else {
Toast.makeText(Signin.this, "please try again",
Toast.LENGTH_LONG).show();
}
}
}
public String[] parseJsonObject(String result) {
JSONObject obj = null;
try {
obj = new JSONObject(result);
if (obj.has("success")) {
if (obj.getInt("success") == 1) {
if (obj.has("user_pic")) {
return new String[] {
String.valueOf(obj.getInt("user_id")),
obj.getString("user_name"),
obj.getString("user_pic") };
} else {
return new String[] {
String.valueOf(obj.getInt("user_id")),
obj.getString("user_name"), };
}
} else {
return null;
}
} else {
return null;
}
} catch (JSONException e) {
e.printStackTrace();
return null;
}
}
here my RequestParams are just a object where I stored all the details like url parameters to send etc and the output of the doinbackground is a String and I am parsing it in my postexecute method
I'm write a music application online.But i'm meet a problem... A new activity starts slowly when I select an item in listview...
I don't know resolve, please help me ! :(
Sorry. I'm speak English very bad :(
This is my code:
public class startNewActivity extends AsyncTask<String, Void, String> {
private Activity activity;
private String selectDoc = "div.gen img";
private String attr = "title";
private String result;
public String Quality;
public startNewActivity(Activity activity) {
this.activity = activity;
}
#Override
protected String doInBackground(String... arg0) {
nameSong = (String) lvSong.getItemAtPosition(positionId);
link = linkSong.get(Integer.valueOf(obj.toString()));
Quality = Utils.getQuality(link, selectDoc, attr, result);
Log.i("Quality", Quality);
changeLink = link.replace(".html", "_download.html").substring(15)
.replaceFirst("", "http://download")
.replace("nhac-hot", "mp3".concat("/vietnam/v-pop"));
Log.i("Change link", changeLink);
try {
//Connect internet
linkIntent = Utils.getLinkPlay(selectLinkPlay, changeLink,
afterChangeLink);
} catch (Exception e) {
Toast.makeText(getApplicationContext(),
"Server has problem... Please while for minutes",
Toast.LENGTH_SHORT).show();
}
return linkIntent;
}
#Override
protected void onPostExecute(String result) {
//i'm want help here
Intent i = new Intent(SongActivity.this, PlayMusicActivity.class);
i.putExtra("song", linkIntent);
i.putExtra("namesong", nameSong);
i.putExtra("Quality", Quality);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
activity.startActivity(i);
pDialog.dismiss();
super.onPostExecute(result);
}
#Override
protected void onPreExecute() {
pDialog = ProgressDialog.show(SongActivity.this, "",
"Please wait...");
}
}
You're starting the new activity inside onPostExecute() which executes only after you've completed doInBackground(). Hence, the time delay.
Ideally, you should start the activity just after you execute your AsyncTask. The AsyncTask will continue in the background while your activity changes.
I want to use AsyncTask for receiving ArrayList's(in this case) from Java server. To be sure, that I received something from server I'm trying to display it with Toast.
The Code is following:
public class MainActivity extends Activity {
private DataReceiving dRec;
private DataTransfer dTrans;
private EditText inputData;
private Button sendParametersBtn;
private Button startComputationBtn;
private TextView displayText;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
inputData=(EditText) findViewById(R.id.InputText);
sendParametersBtn=(Button) findViewById(R.id.button1);
startComputationBtn=(Button) findViewById(R.id.button2);
displayText=(TextView) findViewById(R.id.textView1);
sendParametersBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
dRec = new DataReceiving();
dRec.execute();
}
});
private class DataReceiving extends AsyncTask<Void, Void, ArrayList>
{
#Override
protected ArrayList doInBackground(Void... params) {
ArrayList b = new ArrayList();
try {
b = receive();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return b;
}
protected void onPostExecute(ArrayList result) {
super.onPostExecute(result);
Toast toast=Toast.makeText(getApplicationContext(), result.toString(), Toast.LENGTH_SHORT);
toast.show();
}
public ArrayList receive () throws IOException, ClassNotFoundException
{
ServerSocket s= new ServerSocket(8888);
Socket incoming =s.accept();
ObjectInputStream ios = new ObjectInputStream(incoming.getInputStream());
ArrayList b = (ArrayList) ios.readObject();
ios.close();
incoming.close();
s.close();
return b;
}
While clicking the sendParametersBtn nothing happening.
P.S. I can successfully transmit from Android to Server. So its not a connection or permission problem.
Thank you for help
Hi If your getting some thing from server you have to call web server url for fetching data. After data arrives response have some type it will JSON/XML if they are restful services if they are SOAP services they are in envelope. So after response return get that and parse them as per logic.
Look for HTTP get/post (for ping to server and get data )and parsing (JSON/XML).
Figured out! I removed receive method into doInBackground.
I have a difficulty with my database connection. I have a DataManager which creates the Database connection etc. I also created an Application class which creates this DataManager so the UI Thread can get the data. Now the problem is that there is a background thread which also needs access to the database, and I am not exactly sure how to do this (currently I get an error when trying to create a new DataManager in the AsyncActivity because the database was not closed (and this is correct, as the UIThread has it open).
So I thought that (and this might not be the right way to do it as it is a different thread) I would get access to the Application and use the same DataManager on a new session. But how can I get access to the Application from an 'ordinary' class without Context or Activity (I have done it before I think, but cannot remember).
The code of the background task is:
public class SyncTask extends AsyncTask<String, Integer, String> {
private static final String TAG = "Sync";
/** application context. */
private Context context;
private ProgressDialog dialog;
public SyncTask(Context aContext) {
//this.activity = activity;
this.context = aContext;
dialog = new ProgressDialog(context);
}
protected void onPreExecute() {
this.dialog.setMessage("Loading...");
this.dialog.setMax(100);
this.dialog.setProgress(0);
this.dialog.show();
}
#Override
protected void onPostExecute(final String errMessage) {
if (dialog.isShowing()) {
dialog.dismiss();
}
if (errMessage == null) {
Toast.makeText(context, "Update completed", Toast.LENGTH_LONG).show();
} else {
AlertDialog alertDialog = new AlertDialog.Builder(context).create();
alertDialog.setTitle("Error...");
alertDialog.setMessage(errMessage);
alertDialog.show();
}
}
protected void onProgressUpdate(Integer... progress) {
Log.d(TAG, "Progress Update: " + progress[0].toString());
super.onProgressUpdate(progress[0]);
dialog.setProgress(progress[0]);
}
protected String doInBackground(final String... args) {
try{
publishProgress( new Float(50).intValue());
iDomsAndroidApp app = ((iDomsAndroidApp) ?? cannot remember ??);
DataManager manager = app.getDataManager();
manager.updateData();
return null;
} catch (Exception e){
Log.e(TAG, "error", e);
return e.getMessage();
}
}
}
You can use getApplicationContext() method of any Context instance you have and cast return to YouApplication. It is absolutelly eligible.
You should use a ContentProvider for accessing the database, it is thread safe and the preferred way to handle your data.
http://developer.android.com/guide/topics/providers/content-providers.html