On Mac : Getting null pointer exception on Inputfilestream

HI,

I started coding using mac for automating by using selenium webdrifer, I am getting null point exception for the following line code:
FileInputStream fn = new FileInputStream(System.getProperty("/Users/Vanaja/Documents/workspace/sai/src/config/config.properties"));

Please see attached screen shot, i tried so many combinations to work but no luck. same file pats is working fine for file reader. Please see the attached screen shot.

Tried with the following none of them worked:

Macintosh HD/Users/Vanaja/Documents/workspace/sai/src/config/config.properties
/Macintosh HD/Users/Vanaja/Documents/workspace/sai/src/config/config.properties

Thanks,
Vanaja.