java - Directory only creates when run on localhost -

good day! wondering why codes on creating directory works on localhost. when project deployed live server , access on client-side, not work anymore.

string path = system.getproperty("user.home") + file.separator + "documents";         path += file.separator + ("custom_folder");         file customdir = new file(path);         customdir.mkdirs(); 

update:

i modified code to

file outreportdir = new file("c:/custom_folder");         outreportdir.mkdir(); 

and creates folder now. problem when client clicks button create folder, folder creates on c:\ of server war file placed, not on user's own c:\ why it? time.