In Gvim file error in non root User and Solution

Error:
$gvim filename.txt
Xlib: connection to ":0.0" refused by server
Xlib: No protocol spectified
E233: connot open displayXlib: connection to ":0.0" refuesed by server
Xlib: No protocol specified

Solution:
xhost localhost:user2
xhost +user
xhost
see the name of localhostuser
xhost +local: username