rxjs - Angular 2 http GET method calling twice -

this question asked here still not able find answer in , believe have done research ,

a. things have done far:

1. i have tried .share link same

2. i have tried check whether preflight reuest , found in network tab:

there 2 option call , 2 call going . so, can sure not preflight request.

now comming towards coding part:

component ------------       constructor(             private _notificationservice: notificationservice) {             this.getnotification();         }       getnotification() {             this._notificationservice.getnotifications().subscribe(notifications => {                 this.notificationlist = notifications;             });         }    service: -------------      constructor(private http: http,private config: configuration) { }       getnotifications() {             const headers = new headers({                 'c-t-tenant': 'tenant name',                 'c-t-apitoken': 'token-name',                 'content-type': 'application/json',             });             return this.http.get(this.config.notificationapiurl, { headers: headers })             .map((res: response) => res.json());         } 

i sure api not getting called somewhere else. if stucked in kind of situation please me here.

my backend in spring boot , have implemented cors filter also:

package com.bosch.cb.dashboard.auth;  import java.io.ioexception;  import javax.servlet.filter; import javax.servlet.filterchain; import javax.servlet.filterconfig; import javax.servlet.servletexception; import javax.servlet.servletrequest; import javax.servlet.servletresponse; import javax.servlet.http.httpservletrequest; import javax.servlet.http.httpservletresponse;  import org.springframework.stereotype.component;  @component public class simplecorsfilter implements filter {      public simplecorsfilter() {         system.out.println("simplecorsfilter init");     }      @override     public void init(filterconfig filterconfig) throws servletexception {     }      @override     public void dofilter(servletrequest req, servletresponse resp, filterchain chain)             throws ioexception, servletexception {            httpservletrequest request = (httpservletrequest) req;             httpservletresponse response = (httpservletresponse) resp;              response.setheader("access-control-allow-origin", "*");             response.setheader("access-control-allow-credentials", "true");             response.setheader("access-control-allow-methods", "post, get, options, delete");             response.setheader("access-control-max-age", "3600");                          response.setheader("access-control-allow-headers", "access-control-allow-headers, pragma, origin,accept, b-h-apitoken ,x-requested-with, content-type, access-control-request-method, access-control-request-headers, authorization");              chain.dofilter(request, response);     }      @override     public void destroy() {     }  } 

try

constructor( private _notificationservice: notificationservice) {     this.getnotification().subscribe(notifications => {         this.notificationlist = notifications;     });  }   getnotification() {    return this._notificationservice.getnotifications(); } 

or workaround of

constructor( private _notificationservice: notificationservice) {     this.getnotification()      .first()      .subscribe(notifications => {          this.notificationlist = notifications;      });  }   getnotification() {    return this._notificationservice.getnotifications(); }