how do I add a userprofile variable normally %userprofile%

Question

I need to add a user profile variable in java, apparently %userprofile% does not work. when I try and enter this into the directory towards the bottom of the code it does not accept it. however I can echo my %userprofil% in command line

userprofile+"\Downloads\file.txt");

Answer 1

String System.getenv(String var)

so

String userprofile = System.getenv("USERPROFILE");

Then manipulate as desired (e.g. append the rest of your path...)

Alternatively, get the whole environment with Map<String,String> System.getenv()