Two push notification not showing

Issue

im currently trying to push notification in my app. i have 2 AsyncTask with notification in it but when execute both two on my log in the second one is only showing,a but when i comment the the second one the first one is showing i know my api is working fine

First asyntask:

public class backWorkerNotifTom extends AsyncTask<String,String,String> {
Context context;
String result;
String[] BookTittle;
    public  backWorkerNotifTom(Context context){this.context = context;}
    @Override
    protected String doInBackground(String... params) {
        String type = params[0];
        String NotifTomURL = "http://192.168.254.120/LibrayAPI/SelectNotifTom.php";
        if (type.equals("SelectNotifTom")){
            String dateTom = params[1];
            String borrowerID = params[2];

            try {
                String data = URLEncoder.encode("date_tom","UTF-8") + "=" +
                        URLEncoder.encode(dateTom,"UTF-8");
                data += "&" + URLEncoder.encode("borrower_id","UTF-8") + "=" +
                        URLEncoder.encode(borrowerID,"UTF-8");

                URL url = new URL(NotifTomURL);
                URLConnection urlConnection = url.openConnection();
                urlConnection.setDoOutput(true);

                OutputStreamWriter outputStreamWriter = new OutputStreamWriter(urlConnection.getOutputStream());
                outputStreamWriter.write(data);
                outputStreamWriter.flush();

                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));

                StringBuilder sb = new StringBuilder();
                String line;

                while ((line = bufferedReader.readLine())!= null){
                    sb.append(line+"\n");
                }
                result = sb.toString();

                JSONArray jsonArray = new JSONArray(result);
                JSONObject jsonObject;
                BookTittle = new String[jsonArray.length()];
                for (int i = 0; i < jsonArray.length(); i++) {
                    jsonObject = jsonArray.getJSONObject(i);
                    BookTittle[i] = jsonObject.getString("BookTittle");
                    // PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, new Intent(context, NotifList.class), 0);
                    NotificationCompat.Builder mbuilder = new NotificationCompat.Builder(context)
                            .setSmallIcon(R.drawable.ic_book_black_24dp)
                            .setContentTitle("Library Alert")
                            .setContentText("Tommorow is the Due Day of the Book " + BookTittle[i] + " You Borrowed")

                            //.setContentIntent(pendingIntent)
                            .setTicker("Notifications");

                    NotificationManager notificationManager = (NotificationManager) context.getSystemService(context.NOTIFICATION_SERVICE);

                    if (notificationManager != null) {
                        notificationManager.notify(i, mbuilder.build());
                    }
                }
            }
            catch (Exception ex){
                ex.printStackTrace();

            }


        }
        return result;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);

    }
}

Second Asyntask:

public class backWorkerNotif extends AsyncTask<String, String, String> {
    String result = null;
    String[] BookTittle;
   Context context;
   public  backWorkerNotif(Context context){this.context = context;}

    @Override
    protected String doInBackground(String... params) {
        String selectNotif_url = "http://192.168.254.120/LibrayAPI/SelectNotif.php";
        String type = params[0];

        if (type.equals("Notif")) {
            String DateNow = params[1];
            String BorrowerID = params[2];
            try {

                String data = URLEncoder.encode("date_now", "UTF-8") + "=" +
                        URLEncoder.encode(DateNow, "UTF-8");
                data += "&" + URLEncoder.encode("borrower_id", "UTF-8") + "=" +
                        URLEncoder.encode(BorrowerID, "UTF-8");

                URL url = new URL(selectNotif_url);
                URLConnection urlConnection = url.openConnection();
                urlConnection.setDoOutput(true);

                OutputStreamWriter outputStreamWriter = new OutputStreamWriter(urlConnection.getOutputStream());

                outputStreamWriter.write(data);
                outputStreamWriter.flush();

                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
                StringBuilder sb = new StringBuilder();
                String line;
                while ((line = bufferedReader.readLine()) != null) {

                    sb.append(line + "\n");
                }
                result = sb.toString();
                if (result.isEmpty()) {
                } else {
                    //Json

                    JSONArray jsonArray = new JSONArray(result);
                    JSONObject jsonObject;
                    BookTittle = new String[jsonArray.length()];
                    for (int i = 0; i < jsonArray.length(); i++) {
                        jsonObject = jsonArray.getJSONObject(i);
                        BookTittle[i] = jsonObject.getString("BookTittle");
                       // PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, new Intent(context, NotifList.class), 0);
                        NotificationCompat.Builder mbuilder = new NotificationCompat.Builder(context)
                                .setSmallIcon(R.drawable.ic_book_black_24dp)
                                .setContentTitle("Library notification")
                                .setContentText("Today is the Due Day of the Book " + BookTittle[i] + " You Borrowed")

                                //.setContentIntent(pendingIntent)
                                .setTicker("Notification Alert");

                        NotificationManager notificationManager = (NotificationManager) context.getSystemService(context.NOTIFICATION_SERVICE);

                        if (notificationManager != null) {
                            notificationManager.notify(i, mbuilder.build());
                        }
                    }
                }
            }
            catch (Exception ex) {
                ex.printStackTrace();

            }


        }

        return null;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    protected void onPostExecute(String jsonArray) {
        super.onPostExecute(jsonArray);

    }
}

Log in class

public class Login extends AppCompatActivity {

    EditText username,password;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        username = findViewById(R.id.edtUsername);
        password = findViewById(R.id.edtPassword);
    }

    public void onLogin(View view) {

        String Username = username.getText().toString();
        String Password = password.getText().toString();
        //notif call
        //call notif for overdue tommorow
        backWorkerNotifTom backWorkerNotifTom = new backWorkerNotifTom(this);
      //get datetime tom
       Calendar calendar =  Calendar.getInstance();
        calendar.add(Calendar.DAY_OF_YEAR,1);
        Date dateTom = calendar.getTime();
        SimpleDateFormat sf1 = new SimpleDateFormat("yyyy-MM-dd");
        String dateTomString = sf1.format(dateTom);
        Toast.makeText(this, dateTomString, Toast.LENGTH_SHORT).show();
        backWorkerNotifTom.execute("SelectNotifTom",dateTomString,Username);

        backWorkerNotif backWorkerNotif = new backWorkerNotif(this);
        Date date = Calendar.getInstance().getTime();
        SimpleDateFormat SF = new SimpleDateFormat("yyyy-MM-dd");
        String DateNow = SF.format(date);
        backWorkerNotif.execute("Notif", DateNow, Username);

        String Type = "login";
        GlobalVariable.BorrowerID = Username;
        GlobalVariable.Password = Password;
        backgroundWorker _backgroundWorker = new backgroundWorker(this);
        _backgroundWorker.execute(Type, Username, Password);


    }
}

Solution

This is probably happening because you're using the same IDs when making both types of notification. This will cause the second one to overwrite the first. If you want to show multiple notifications, each one will need a separate ID.

The problematic line of code is notificationManager.notify(i, mbuilder.build()); in both async tasks. Because 'i' is created as an int ranging from 0 array length, you're getting a lot of conflicts between the two tasks. You need to make sure each notification uses a unique ID

Answered By - Hofma Dresu