Comparing lines in a text file.

[Rodrigo Aguilera]

Hi, i am learning Java and i need to make a little program that gets a text file and search for duplicate lines in it. The lines in the text file look like this :
2004-12-19 00:00:00.000,105,19:57:26,INI,DISCANDO INTRANET
2004-12-19 00:00:00.000,105,19:57:26,INI,DISCANDO INTRANET

Maybe there is a method to make this work.

thanks in advance.

[Stan James]

Do you want to display duplicates or eliminate them? I started out thinking eliminate, but it's hard to tell from your question.

If duplicates appear next to each other, something like this will copy a file and remove duplicate lines:

priorLine = null;
while( null != ( thisLine = readline() ) )
{
   if ( thisLine.equals(priorLine) )
      display "found a duplicate!"
   else
      write thisLine to new file or a linked list
   priorLine = thisLine
}

If duplicates could appear anywhere, look into the Collections APIs to find one that doesn't store duplicates or one you could ask if a line already exists. Here's my Collections Crib Sheet that may help.

while ( null != ( thisLine = readline() ) ) )
{
   if collection already has thisLine
      display "Found a duplicate!"
   else
      collection add thisLine
}

Let us know what you choose!
[ December 20, 2004: Message edited by: Stan James ]

[Rodrigo Aguilera]

Thanks for the tip. I would like to remove the duplicated lines. I will let you know when i finish it.

thanks.