Trying to create file without succes - file appears elsewhere?

Trying to create file without succes - file appears elsewhere?

I tried to create 3 empty files in my home directory, using this:
this.mainpath = System.getenv("HOME"+"/");
this.single = new File(mainpath + "sin.r");
this.complete = new File (mainpath + "com.r");
this.ward = new File (mainpath+"w.r");
I was unter the impression that this would give me the files desired.
However, if I search my home directory, or any other directory, for this
files, none of them exists. What am I doing wrong?
Edit: I just find out: I do get a file, but not in my home directory, but
the path to it would be
/home/myname/NetBeansProjects/myorojectname/nullsin.r.
However, I specifically wanted to create the file in my home!
Well, my code now reads:
this.mainpath = System.getenv("user.home");
this.mainpath = this.mainpath + "/";
this.single = new File(mainpath + "sin.r");
this.single.createNewFile();
System.out.println(this.single.getAbsolutePath());
this.complete = new File (mainpath + "comp.r");
this.complete.createNewFile();
this.ward = new File (mainpath+"w.r");
this.ward.createNewFile();
The "success" of this, however, is that I get an IOException at the first
createNeWFile(): File not found.