java - Error with Notification.Builder in notify -

hello new android, , 'm trying create notifications notification.builder , failed . when launching notification error

nm.notify(idnotificacionuno,notif); // error in notif  

i have downloaded api 's 16 17 18 19 23, , code :

public class mainactivity extends appcompatactivity { notificationmanager nm; private static final int idnotificacionuno = 1; notification notif;   @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); button btnlanzar = (button) findviewbyid(r.id.boton_notificacion);  btnlanzar.setonclicklistener(new view.onclicklistener() {         @override         public void onclick(view v) {  intent = new intent(getapplicationcontext(),segundaventana.class);  pendingintent intencionpendiente =  pendingintent.getactivity(getapplicationcontext(),0,i,0);    notification.builder notif = new notification.builder(getapplicationcontext());  notif.setsmallicon(r.drawable.tree); notif.setticker("app nature ¡tip!"); notif.setwhen(system.currenttimemillis());  notif.setcontenttitle("app nature ¡tip!"); notif.setcontenttext("cierra la llave, cuando te estes cepillando"); notif.setcontentinfo("tip"); notif.setcontentintent(intencionpendiente);   nm = (notificationmanager)getsystemservice(notification_service);               nm.notify(idnotificacionuno,notif);   }   });  } 

i libraries . thank help

there ` characheter after notif.setsmallicon(r.drawable.tree); remove charachter , code run.