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Code to Modify the contents of a file

Moni Marva
Greenhorn

Joined: Jan 24, 2005
Posts: 23
Hi,
The contents of the .log file are as mentioned below,

12/02/2005,12:30:06:09,12/02/2005,12:40:09:09,failure,ind-mhp1dxp0323

In this I want to change the status from say "failure" to "sucess" for a particular line.
I want the solution to do this using File Io , Random Access file.
sandip mense
Greenhorn

Joined: Oct 14, 2003
Posts: 28
Moni,

These are the steps that you need to follow,

Load the file from the file system.
Open the file in read/write mode.
Read the line into a StringBuffer.
Get the length of the string that you want to replace
Replace the String using the StringBuffer replace(startindex, endindex, Stringtoreplace) method

Sandip
Stan James
(instanceof Sidekick)
Ranch Hand

Joined: Jan 29, 2003
Posts: 8791
With RandomAccess you can locate a string in a file and overwrite it with something else of exactly the same length. Since "failure" and "success" both have 7 letters you could do it in place. The "locate" part might be a little challenging, though, since there's no API to read one line at a time from RandomAccess.

With ordinary file io you can read the input one line at a time, examine each line, make the change when you find the target, and write a new file one line at a time. I like this trick to be very safe when rewriting a file:


A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: Code to Modify the contents of a file