• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Jeanne Boyarsky
  • Ron McLeod
  • Paul Clapham
  • Liutauras Vilda
Sheriffs:
  • paul wheaton
  • Rob Spoor
  • Devaka Cooray
Saloon Keepers:
  • Stephan van Hulst
  • Tim Holloway
  • Carey Brown
  • Frits Walraven
  • Tim Moores
Bartenders:
  • Mikalai Zaikin

Parsing text file into 3 columns

 
Greenhorn
Posts: 22
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Hi,
I have a requirement to parse the text file (sample pasted below) and extract the 3 said columns in the file. I am using the Scanner class, but I cannot seem to leverage the "useDelimiter" method to trim the spaces in the text file..

Sample file

64.105.4.90 mail.virtuosoworks.com. ptr
64.105.4.178 mail.imaamd.org. ptr
64.105.4.186 smtp.vernonlaw.com. ptr
64.105.5.25 64-105-5-25.adsl.lbdsl.net. ptr
64.105.5.26 stitch.chipworks.net. ptr
64.105.5.27 studley.chipworks.net. ptr
64.105.5.28 heman.chipworks.net. ptr
64.105.5.29 xena.chipworks.net. ptr
64.105.9.133 MAIL.LINCOLNINDUSTRIAL.COM. ptr
64.105.9.137 DNS1.LINCOLNINDUSTRIAL.COM. ptr

Code below is extracting the 1st column (IP address), but not finding the 2nd and 3rd column. Any help is appreciated. ptr is the 3ed column - its sometimes 1 space after the 2nd column and sometimes multiple spaced after the 2nd column. This file is auto-generated by a mysterious script.

 
author
Posts: 23951
142
jQuery Eclipse IDE Firefox Browser VI Editor C++ Chrome Java Linux Windows
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator


The default delimiter is "one or more whitespaces" -- so there is no need to set the delimiter, as it is correct. In fact, the delimiter that you set is exactly one space, and since you mention that there may be more than one space, is actually incorrect.

Henry
 
Sheriff
Posts: 22784
131
Eclipse IDE Spring VI Editor Chrome Java Windows
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
aLine.split("\\s+") is also an option.
 
Ranch Hand
Posts: 2874
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Rob Prime wrote:aLine.split("\\s+") is also an option.



And this one will be more efficient in terms of performance.
 
Rob Spoor
Sheriff
Posts: 22784
131
Eclipse IDE Spring VI Editor Chrome Java Windows
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
I wouldn't dare say that without some figures to back it up. Both Scanner and String.split use a java.util.regex.Pattern object. Both these pieces of code create this for each line.
It is likely though that String.split is more efficient since Scanner uses several Pattern objects.

You are right that both are not really efficient. The Pattern can be pulled out of the loop with String.split though:
I've searched the Scanner API but there is no way to reset the Scanner with new input. Therefore, the String.split way will be the more efficient.
 
Adeel Ansari
Ranch Hand
Posts: 2874
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Rob Prime wrote:I wouldn't dare say that without some figures to back it up...



Actually, I have benchmarked both few months ago, using File IO.. reading ... and then splitting strings based on some token. I tried both Scanner, and String's split. The latter seemed faster.
 
Rob Spoor
Sheriff
Posts: 22784
131
Eclipse IDE Spring VI Editor Chrome Java Windows
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Well, then you have some figures to back your claim
 
reply
    Bookmark Topic Watch Topic
  • New Topic