Emacs: Show line number from editor

Download setnu.el from:
http://www.emacswiki.org/cgi-bin/wiki/setnu.el

Append the below two lines to setnu.el lisp code.
(add-hook 'c-mode-hook 'turn-on-setnu-mode)
(add-hook 'java-mode-hook 'turn-on-setnu-mode)

Load it from .emacs file.

Done. Now, you can see the line number from Emacs editor when you are editing C or Java source codes.