Regex in a text file

Hello friends, I'm a newbie to java. I have to develop an application in which we can find the strings and replace them with another strings and all this in a text file stored on my hard disk. Could anyone suggest me, how to do?Thanx in advance
[266 byte] By [Yagayavalkaa] at [2007-11-27 3:37:10]
# 1
Check out this tutorial on [url http://java.sun.com/docs/books/tutorial/essential/regex/index.html]Regular Expressions[/url]
abillconsla at 2007-7-12 8:40:26 > top of Java-index,Java Essentials,New To Java...