How to use Handler in AsynkTask in android

Question

I am fetching data from server using AsynkTask which works fine but I want to use handler in AsynkTask to reduce load from main Thread.How can I use Handler in AsynkTask. Kindly help me to solve this problem.

Here is my code.

public class CLoginScreen extends Fragment {
public static String s_szLoginUrl = "http://192.168.0.999:8080/rest/json/metallica/getLoginInJSON";
public static String s_szresult = " ";
public static String s_szMobileNumber, s_szPassword;
public static String s_szResponseMobile, s_szResponsePassword;
public View m_Main;
public EditText m_InputMobile, m_InputPassword;
public AppCompatButton m_LoginBtn, m_ChangePass, m_RegisterBtn;
public CJsonsResponse m_oJsonsResponse;
public boolean isFirstLogin;
public JSONObject m_oResponseobject;
public LinearLayout m_MainLayout;
public CLoginSessionManagement m_oLoginSession;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    m_Main = inflater.inflate(R.layout.login_screen, container, false);
    ((AppCompatActivity) getActivity()).getSupportActionBar().hide();
    m_oLoginSession = new CLoginSessionManagement(getActivity());
    init();
    return m_Main;
}

public void init() {
    m_MainLayout = (LinearLayout) m_Main.findViewById(R.id.mainLayout);


    m_InputMobile = (EditText) m_Main.findViewById(R.id.input_mobile);
    m_InputPassword = (EditText) m_Main.findViewById(R.id.input_password);

    m_LoginBtn = (AppCompatButton) m_Main.findViewById(R.id.btn_Login);
    m_ChangePass = (AppCompatButton) m_Main.findViewById(R.id.btn_ChangePass);
    m_ChangePass.setBackgroundColor(Color.TRANSPARENT);
    m_ChangePass.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.container, new CChangePasswordScreen()).commit();
        }
    });

    m_RegisterBtn = (AppCompatButton) m_Main.findViewById(R.id.btn_Register);
    m_RegisterBtn.setBackgroundColor(Color.TRANSPARENT);
    m_RegisterBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.container, new CRegistrationScreen()).commit();
        }
    });
    m_LoginBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            new LoginAttempt().execute();
        }
    });
}

private class LoginAttempt extends AsyncTask<String, Void, String> {
    public Dialog m_Dialog;
    public ProgressBar m_ProgressBar;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        m_Dialog = new Dialog(getActivity());
        m_Dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
        m_Dialog.setContentView(R.layout.progress_bar);
        showProgress("Please wait while Logging...");// showing progress ..........
    }

    @Override
    protected String doInBackground(String... params) {
        getLoginDetails();// getting login details from editText...........
        InputStream inputStream = null;
        m_oJsonsResponse = new CJsonsResponse();
        isFirstLogin = true;
        try {
            // 1. create HttpClient
            HttpClient httpclient = new DefaultHttpClient();
            // 2. make POST request to the given URL
            HttpPost httpPost = new HttpPost(s_szLoginUrl);
            String json = "";
            // 3. build jsonObject
            JSONObject jsonObject = new JSONObject();
            jsonObject.put("agentCode", s_szMobileNumber);
            jsonObject.put("pin", s_szPassword);
            jsonObject.put("firstloginflag", m_oLoginSession.isLogin());
            // 4. convert JSONObject to JSON to String
            json = jsonObject.toString();
            // 5. set json to StringEntity
            StringEntity se = new StringEntity(json);
            // 6. set httpPost Entity
            httpPost.setEntity(se);
            // 7. Set some headers to inform server about the type of the content
            //  httpPost.setHeader("Accept", "application/json");   ///not required
            httpPost.setHeader("Content-type", "application/json");
            // 8. Execute POST request to the given URL
            HttpResponse httpResponse = httpclient.execute(httpPost);
            HttpEntity entity = httpResponse.getEntity();
            // 9. receive response as inputStream
            inputStream = entity.getContent();
            System.out.print("InputStream...." + inputStream.toString());
            System.out.print("Response...." + httpResponse.toString());

            StatusLine statusLine = httpResponse.getStatusLine();
            System.out.print("statusLine......" + statusLine.toString());
            ////Log.d("resp_body", resp_body.toString());
            int statusCode = statusLine.getStatusCode();
            if (statusCode == 200) {
                // 10. convert inputstream to string
                if (inputStream != null) {
                    s_szresult = m_oJsonsResponse.convertInputStreamToString(inputStream);
                    //String resp_body =
                    EntityUtils.toString(httpResponse.getEntity());
                }
            } else
                s_szresult = "Did not work!";

        } catch (Exception e) {
            Log.d("InputStream", e.getLocalizedMessage());
        }
        System.out.println("s_szResult....." + s_szresult);
        System.out.println("password......" + s_szPassword);
        // 11. return s_szResult
        return s_szresult;
    }

    @Override
    protected void onPostExecute(String response) {
        super.onPostExecute(response);
        hideProgress();// hide progressbar after getting response from server......
        try {
            m_oResponseobject = new JSONObject(response);// getting response from server
            new Thread() {// making child thread...
                public void run() {
                    Looper.prepare();
                    try {
                        getResponse();// getting response from server
                        Looper.loop();
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }.start();

        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    public void getResponse() throws JSONException {
        if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Transaction Successful")) {
            m_oLoginSession.setLoginData(s_szResponseMobile, s_szResponsePassword);
            getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.container, new CDealMainListing()).commit();
        } else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Agentcode Can Not Be Empty")) {
            showToast("Please Enter Valid Mobile Number");
        } else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Pin Can Not Be Empty")) {
            showToast("Please Enter Password");
        } else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Invalid PIN")) {
            showToast("Invalid Password");
        } else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Subscriber/Agent Blocked due to Wrong Attempts")) {
            showToast("You are blocked as You finished you all attempt");
        } else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Connection Not Available")) {
            showToast("Connection Lost ! Please Try Again");
        } else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Subscriber/Agent Not Found")) {
            showToast("User not found ! Kindly Regiter before Login");
        } else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("OTP not verify")) {
            showToast("Otp not Verify ! Kindly Generate Otp on Sign Up");
        }
    }

    public void showToast(String message) {// method foe showing taost message
        Toast toast = Toast.makeText(getActivity(), "" + message, Toast.LENGTH_SHORT);
        toast.setGravity(Gravity.CENTER, 0, 0);
        toast.show();
    }

    public void getLoginDetails() {
        s_szMobileNumber = m_InputMobile.getText().toString();
        s_szPassword = m_InputPassword.getText().toString();
    }

    public void showProgress(String message) {
        m_ProgressBar = (ProgressBar) m_Dialog.findViewById(R.id.progress_bar);
        TextView progressText = (TextView) m_Dialog.findViewById(R.id.progress_text);
        progressText.setText("" + message);
        progressText.setVisibility(View.VISIBLE);
        m_ProgressBar.setVisibility(View.VISIBLE);
        m_ProgressBar.setIndeterminate(true);
        m_Dialog.setCancelable(false);
        m_Dialog.setCanceledOnTouchOutside(false);
        m_Dialog.show();
    }

    public void hideProgress() {
        m_Dialog.dismiss();
    }
}

}

you dont need any `Handler`s in `AsyncTask`, just call your UI inside the callbacks that are executed on the UI thread — pskink, Mar 28 '16 at 05:10
asynctask is used to perform operations on background thread. — Vivek Mishra, Mar 28 '16 at 06:10

score 0 · Answer 1 · edited Mar 28 '16 at 05:25

0

You Can Use

     getActivity().runOnUiThread(new Runnable() {
         @Override
         public void run() {
             getResponse();
         }
     });

edited Mar 28 '16 at 05:25

Sanoop Surendran

3,484
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answered Mar 28 '16 at 05:06

Abhishek Patel

4,280
1
24
38

score 0 · Answer 2 · answered Mar 28 '16 at 05:19

As per android docs here

An asynchronous task is defined by a computation that runs on a background thread and whose result is published on the UI thread.

And loading data from URL with Handler is not a good thing. Instead use Executor or ThreadPoolExecutor to do heavy background tasks.

score 0 · Answer 3 · edited Mar 28 '16 at 07:40

you can do like this:

class MyAsyncTask extends AsyncTask<Object,Object,Object>{

    Private Context c;
    private Handler handler;

    private final static int YOUR_WORK_ID = 0x11;

    public  MyAsyncTask(Context c,Handler handler){
      this.c = c;
      this.handler = handler;

  }

    protected Object doInBackground(Object... params){
      //do your work
        ...
       Message m =  handler.obtainMessage();
       m.what = YOUR_WORK_ID;
       ...
       handler.sendMessage().sendToTarget(); 


  }



}

And in your fragment ,you can init a handler as params to MyAsyncTask,and deal with you work in handleMessage();

How to use Handler in AsynkTask in android

3 Answers3