android show notification like viber when app is in background

Manifest.xml

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<activity android:name=".pushnotification.NewMsgDialogActivity" android:theme="@android:style/Theme.Translucent.NoTitleBar"  />







MyFirebaseMEssagingService.java

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 final Intent intent = new Intent(MyFirebaseMEssagingService.this, NewMsgDialogActivity.class);

        intent.putExtra("trainerId", trainer_id);

        intent.putExtra("trainer_image_str", trainer_image_str);

        intent.putExtra("trainer_name", trainer_name);


        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK);


        PendingIntent pendingIntent = PendingIntent.getActivity(MyFirebaseMEssagingService.this, 0, intent, 0);

        try {

            // Perform the operation associated with our pendingIntent

            pendingIntent.send();


        } catch (PendingIntent.CanceledException e) {

            e.printStackTrace();

        }




NewMsgDialogActivity.java

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public class NewMsgDialogActivity extends Activity {

    String trainerId, trainer_name, trainer_image_str = "";

    public  static  String new_msg = "";


    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);


        show_new_msg_dialog();

    }


    public void show_new_msg_dialog() {

        AlertDialog.Builder dialog = new AlertDialog.Builder(this);


        dialog.setTitle(getResources().getString(R.string.new_msg))

                .setCancelable(false)

                .setIcon(R.drawable.messages_icon)

                .setMessage(NewMsgDialogActivity.new_msg)

                .setNegativeButton("Ignore", new DialogInterface.OnClickListener() {

                    public void onClick(DialogInterface dialoginterface, int i) {

                        dialoginterface.dismiss();

                        finish();

                    }

                })

                .setPositiveButton("Check", new DialogInterface.OnClickListener() {

                    public void onClick(DialogInterface dialoginterface, int i) {

                        goto_voice_msg_activity();

                        dialoginterface.dismiss();

                        finish();

                    }

                }).show();

    }



    @Override

    public void onBackPressed() {

        super.onBackPressed();

        finish();

    }

}