File and Making Directories on Mac

Question

I hope I put this question in the right place.
I recently found out it is possible make directories using from the File class (.mkdir()), and I've been trying to use it in my program on my Mac, but it doesn't want to make the folder. I don't know why its not making the folder. I've been compiling and running my program from version 1.4.2_07 on Tiger. Here is my code:
public static String makeDirForLib()
     File folder = new File("~/Documents/Lib/");
     folder.mkdir(); //this keeps returning false; I checked and the folder was not created
     return folder.getPath();
}I appreciate the help.

Answer 1

But "~/Documents/" does exist. Its the Documents folder in the current default Home directory. Does Java not recognize that "~", in Unix, is the same thing as typing out "/Users/<UsernameHere>/"?
I want the program to be able to create a separate folder in each Home directory depending on which login a user running it in. By using "~", I was trying to get Java to recognize that it should install in the default Home directory, meaning that if say my sister was running the program from her login, it would install in her Home directory, and if I ran the program from my login, it would install on my Home directory. Is there a solution to this, or an alternate method of achieving this?