Win a copy of Think Java: How to Think Like a Computer Scientist this week in the Java in General forum!
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic

reporting changes (help please!)

 
Rick Jones
Greenhorn
Posts: 6
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi guys,

After creating a small program that lists files, how would I go about craeting a process that scans the directory for changes and reports them. The lastModified() method just shows the date and time of last modification. There must be a more efficient way to do this, right?
 
Stan James
(instanceof Sidekick)
Ranch Hand
Posts: 8791
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I think you're right on track with listing the files and examining the lastModified() time. For recent changes, compare last modified to whatever you define as "recent" or the last time you ran.
 
Yevgeniy Treyvus
Ranch Hand
Posts: 48
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
In terms of efficiency, I don't think there's any way to make this operation any faster than O(n).

In terms of implementation, I think it might turn out a bit tedious to keep track of all the last modified dates for all the files -- especially if you have a lot of files.

Instead, try generating a hash for all the files within a directory (recursive operation). This way you only have to keep track of one number, as opposed to possibly thousands of last modified dates. If the hashes don't match that means something has changed.
 
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic