Convert android AsyncTask call to a separate class and call from all activities

Question

I am new to android development. I have a AsyncTask function in my application. Calling http request from all activities. Now in each activity I am using the following class to connect to server, in some activities I even called twice !!.

Basically I am a web developer and in such cases we use a single class which can be accessed from entire application(web) and use the common function to do the same activity. The only difference is input and out put will be changed.

My doubt is in this case can I use ( convert) this to such a function or class ? My assume is

Create an android class ( which can be accessed from all the activities )
Just make the JSON string we need with specific server ( for process in server )
Just pass the created json to the created class and then made the http connect )
Process the returned data from server
Pass that to the corresponding activity

So that I can use the same function for all the activities and I can avoid duplicate query

Can I convert this code to such a manner ?

My Code

public class MainActivity extends Activity {




    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setRequestedOrientation (ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        setContentView(R.layout.activity_main);

                LogIN loginUser = new LogIN();
        LoginUser.execute("");


}

         private class LogIN extends AsyncTask<String, Integer, String> {


        @Override
        protected String doInBackground(String... sUrl) {
            try {


        String path = "http://www.domain_name.com/app/checkSession.php";

        HttpClient client = new DefaultHttpClient();
        HttpConnectionParams.setConnectionTimeout(client.getParams(), 10000); 

                HttpResponse response;
                JSONObject json = new JSONObject();
                try {
                    HttpPost post = new HttpPost(path);
                    json.put("access_token", "123456");


                    post.setHeader("json", json.toString());
                    StringEntity se = new StringEntity(json.toString());
                    se.setContentEncoding((Header) new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
                    post.setEntity(se);

              response = client.execute(post);
                    /* Checking response */
                    if (response != null) {
                        InputStream in = response.getEntity().getContent(); 

                        String a = convertStreamToString(in);

                        JSONObject jsono = stringToJsonobj(a);
                        String passedStringValue = jsono.getString("result");

                        if(passedStringValue.equals("1")){
                            flags=1;
                            //Log.v("TAGG", "Success");
                        }
                        else {
                            flags=0;
                            //Log.v("TAGG", "Failed !");
                        }
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }








            } catch (Exception e) {
            }
            return null;
        }

        @Override
        protected void onPreExecute() {


            super.onPreExecute();
            showDialogue("Login Processing", "Loading");
        }

        @Override
        protected void onProgressUpdate(Integer... progress) {
            super.onProgressUpdate(progress);
        }

        @Override
        protected void onPostExecute(String result) {
            if(flags.equals(1)){
            Itent homepage = new Intent(MainActivity.this, RegisterDevice.class);
            startActivity(homepage);
            finish();
            }
            else {
                Intent homepage = new Intent(MainActivity.this, LoginActivity.class);
                startActivity(homepage);
                finish();
            }
            super.onPostExecute(result);
        }

    }

}

Please any one help/advise Thanks in advance

You can always declare Login as a class, just name the class file "Login", and move all your async task code to it — Chor Wai Chun, May 13 '13 at 08:19
The easiest way is to pass a parameter of the `Activity` type to the constructor of the `Login` class. So you can call such methods as `startActivity`, `finish` from your task. — vortexwolf, May 13 '13 at 08:36

Andres L · Accepted Answer · 2013-05-13T11:01:43.907

Extract your class to a different file and make it public

    public class LogIN extends AsyncTask<Object, Integer, String> {
        private ILoginListener listener;

        @Override
        protected String doInBackground(Object... arg0) {
            try {
               this.listener = (ILoginListener) arg0[0];
              //You can also send the url in the obj array
              String theUrl = (String) arg0[1];


        String path = "http://www.domain_name.com/app/checkSession.php";

        HttpClient client = new DefaultHttpClient();
        HttpConnectionParams.setConnectionTimeout(client.getParams(), 10000); 

                HttpResponse response;
                JSONObject json = new JSONObject();
                try {
                    HttpPost post = new HttpPost(path);
                    json.put("access_token", "123456");


                    post.setHeader("json", json.toString());
                    StringEntity se = new StringEntity(json.toString());
                    se.setContentEncoding((Header) new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
                    post.setEntity(se);

              response = client.execute(post);
                    /* Checking response */
                    if (response != null) {
                        InputStream in = response.getEntity().getContent(); 

                        String a = convertStreamToString(in);

                        JSONObject jsono = stringToJsonobj(a);
                        String passedStringValue = jsono.getString("result");

                        if(passedStringValue.equals("1")){
                            flags=1;
                            //Log.v("TAGG", "Success");
                        }
                        else {
                            flags=0;
                            //Log.v("TAGG", "Failed !");
                        }
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }








            } catch (Exception e) {
            }
            return null;
        }

        @Override
        protected void onPreExecute() {


            super.onPreExecute();
            showDialogue("Login Processing", "Loading");
        }

        @Override
        protected void onProgressUpdate(Integer... progress) {
            super.onProgressUpdate(progress);
        }

        @Override
        protected void onPostExecute(String result) {
            listener.logInSessionCheckListener(flag.equals(1));
            super.onPostExecute(result);
        }

    }

Regarding your other question, I normally have an interface for that, something like this:

    public interface ILoginListener {

        public void logInSessionCheckListener(SomeNeeded Value);

     }

I implement the interface in the class where i need the postExecute result and in the overriden method you can to what you want with the result of your task. Your class where you user it will look something like this:

public class SomeClass implements ILoginListener { 

    //Call it like this from any class:

    LogIN loginTask = new LogIn();

    Object[] someParams = new Object[2]; 
    //add the listener
    someParams[0] = SomeClass.this
    //add the url 
    someParams[1] = someUrlString;

    loginTask.execute(someParams);

   @Override
   public void logInSessionCheckListener(SomeNeeded Value){
    //do Stuff with your results

   }
}

hi one more doubt .. how to get the returned out from server ? I mean if I returned something in "onPostExecute" may I get that on my activity ? — ramesh, May 13 '13 at 08:24
so think im there now, pls call the asyntask with a obj array with your listener and url inside you can check the code, and ask if you dont understand it. have fun — Andres L, May 13 '13 at 08:48
yea.. one doubt still pending... after onPostExecute I have to return something ( json array, json object ) to my activity ... then only I can fetch data and all .. my question is how to return the server out put back to activity ? is it from onPostExecute method ? — ramesh, May 13 '13 at 08:53
yes use the listener for this, change the parameters in the method on the interface so you can take ( json array, json object ) or anything you need — Andres L, May 13 '13 at 08:55
ok .. so I have to add the last part of your code ( "public interface ILoginList..." ) inside my AscTask class ? I am confused there ? Can you please help ? — ramesh, May 13 '13 at 08:58
First you have to create an interface in a different file and then copy paste the text from above. Second in the class where you call the asynctask in the class declaration add: implements ILoginListener, someone edited my text and thats why it looks confusing now... — Andres L, May 13 '13 at 09:02
so i added how your class should look like maybe now it will be clearer for you — Andres L, May 13 '13 at 09:10
ok thanks .. may I have to create a new class and put the "public interface ILoginListener" in that ? — ramesh, May 13 '13 at 09:19
yes, the file would be called " ILoginListener.java" there you copy the code — Andres L, May 13 '13 at 09:24
thanks for your help... now getting an error around "public class LogIN extends" its... 1 method to implement: - android.os.AsyncTask.doInBackground() any ideas ? — ramesh, May 13 '13 at 09:37
in your IDE you can fix it with "add unimplemented methods" or by writing by yourself the overridden methon part of the code in the class — Andres L, May 13 '13 at 09:39
hi. thanks for your effort.. I am getting an error on at listener.logInSessionCheckListener(result); error is : --- com.bg.loc.LogIN.onPostExecute(LogIN.java:117) any idea ? — ramesh, May 13 '13 at 10:51
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/29839/discussion-between-andres-l-and-ramesh) — Andres L, May 13 '13 at 11:01

score 0 · Answer 2 · answered May 13 '13 at 08:23

You can do it like make separate class for everything inside doInBackground() method and called it in all activity with passing parameter to

   LogIN loginUser = new LogIN(yourparameter);
    LoginUser.execute("");

and check parameter in AsyncTask Class constructor like

 public LogIN(Myparameter){
        // Your data
      }

score 0 · Answer 3 · answered May 13 '13 at 08:33

0

On the other hand you can use this great framework for android : android-query and the async API. It allows you to perform asynchroneous network tasks from activities and easily work with the results of your requests.

answered May 13 '13 at 08:33

obo

1,652
2
26
50

score 0 · Answer 4 · edited May 23 '17 at 12:00

0

You should use interfaces to implement a callback to your ui activity. Have a look at this thread, it might be useful: android asynctask sending callbacks to ui And your asyntask class should be in a seperate java file with public acces.

And to pass the parametres you simply have to call a new LogIN async Task like this:

new LogIN().execute(urls);

Hope it helped :)

edited May 23 '17 at 12:00

Community

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1

answered May 13 '13 at 08:35

Thomas

365
1
3
16

score 0 · Answer 5 · answered May 13 '13 at 08:46

Remember that you can never know when AsyncTask is going to finish. So if you're using this to authenticate users and then perform task X, task Y, or task Z,

then maybe it's better to create a Login helper class

public class LoginHelper {

public boolean login(params){
    // Authenticate user and return true if successfull
}

}

and then have in your Activity classes

private class X extends AsyncTask {

@Override
protected String doInBackground(String... sUrl) {

    ...
    boolean authenticated = LoginHelper.login(params...);

    if(authenticated == true) {
        // Perform task X here...
    } else {
        // Inform the user that the login failed...
    }

}

score 0 · Answer 6 · answered May 13 '13 at 08:49

First of all You have to pass the context in which you are calling your async task

Sample Code

Login loginTask = new Long(getContext());
loginTask.execute();

You class Login should have a constructor that accepts the Context

Sample Code

public class Login extends AsyncTask<String, Integer, String> {

private Context mContext ;
private ProgressDialog pd; 
private Handler handler = new Handler { };
public Login (Context context){
mContext = context ;
}
.....

Then make sure to create the method showDialog inside Login class to show the progress dialog

Note You can add what ever Constructors you need to customize the behaviour of your Login task for example : pass boolean parameter to tell that the Login Task is cancelable....

Hope that help you :)

Convert android AsyncTask call to a separate class and call from all activities

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