Java Firebase cloud message . Send message to all -

i want send message device send 1 device how send message : can send message 1 user , when remove @ method send message:

json.put("to", tokenid.trim()); 

a message not send nobody when have line send message 1 user . how can send message every 1 ?

 static void send_fcm_notification(string tokenid, string server_key, string message) {           try {             url url = new url(fcm_url); // create connection.             httpurlconnection conn;             conn = (httpurlconnection) url.openconnection();             conn.setusecaches(false);             conn.setdoinput(true);             conn.setdooutput(true); //set method post or             conn.setrequestmethod("post"); //pass fcm server key             conn.setrequestproperty("authorization", "key=" + server_key); //specify message format             conn.setrequestproperty("content-type", "application/json"); //create json object & pass value             jsonobject infojson = new jsonobject();             infojson.put("title", "wiadomosc z serwera");             infojson.put("sound", "default");             infojson.put("icon", "ic_launcher");             infojson.put("body", message);             jsonobject json = new jsonobject();             json.put("to", tokenid.trim());             json.put("notification", infojson);             outputstreamwriter wr = new outputstreamwriter(conn.getoutputstream());             wr.write(json.tostring());             wr.flush();             int status = 0;             if (null != conn) {                 status = conn.getresponsecode();             }             if (status != 0) {                 if (status == 200) { //success message                     bufferedreader reader = new bufferedreader(new inputstreamreader(conn.getinputstream()));                     system.out.println("android notification response : " + reader.readline());                 } else if (status == 401) { //client side error                     system.out.println("notification response : tokenid : " + tokenid + " error occurred : 401");                  } else if (status == 501) {  //server side error                      system.out.println("notification response : [ errorcode=servererror ] tokenid : " + tokenid);                  } else if (status == 503) {  //server side error                      system.out.println("notification response : fcm service unavailable  tokenid : " + tokenid);                  }               }          } catch (malformedurlexception mlfexception) {  // prototcal error              system.out.println("error occurred while sending push notification!.." + mlfexception.getmessage());          } catch (ioexception mlfexception) {  //url problem              system.out.println("reading url, error occurred while sending push notification!.." + mlfexception.getmessage());          } catch (jsonexception jsonexception) {  //message format error              system.out.println("message format, error occurred while sending push notification!.." + jsonexception.getmessage());          } catch (exception exception) {  //general error or exception.              system.out.println("error occurred while sending push notification!.." + exception.getmessage());          }     } 

firebase supports called topics

so can send message topic , devices subscribed topic push.

you can have topic called all , register each device that.

here how register

firebasemessaging.getinstance().subscribetotopic("all"); 

then can fire notifications topic , users it.

then replace line

json.put("to", tokenid.trim()); 

with

json.put("to", "/topics/your-topic-name"); 

in case topic name all