Replace a String from a file

[Kathiresan Chinnasamy]

Hi friends,

My problem is:

How to replace a particular line(it may be middle) from a file without writing tmp file?

For Example :

Sample.txt contains
one
tow
three

Here i want to insert two instead of tow....

Note:
Delete and rename options are restricted for this file

[Joe Ess]

JavaRanch FAQ: Edit an Existing File