Regex to extract String between two expressions in java

Question

I have a log file that contains sent and received messages. I want to extract these message using a regular expression. This is an example of log file:

Message recieved:0908082349234 Session: ...
A message is sent: 12344384834

I wrote the following regex to extract the message:

String pattern = "((A message is sent: )|(Message received:))(.*)(( Session:)|$)";

And it doesn't work. I tried many different forms of it but none of them worked. I want to do this using a single regex. Right now I use one regex for sent and another one for received. But there should be a way to use a single regex for both of them!

what does not work exactly?

pogopaule
– pogopaule

2013-12-25 10:25:17 +00:00
Commented Dec 25, 2013 at 10:25 — pogopaule
– pogopaule, Commented Dec 25, 2013 at 10:25

falsetru · Accepted Answer · 2013-12-25 10:34:32Z

1

.* matches greedily. Use non-greedy version (.*?):

String pattern = "(A message is sent: |Message received:)(.*?)( Session:|$)";

BTW, the given log file contains a typo. If the log file really contains the typo, you should adjust the regular expression accordingly.

Message recieved:0908082349234 Session: ...
           ^^

edited Dec 25, 2013 at 10:34

answered Dec 25, 2013 at 10:25

falsetru

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4 Comments

hwnd Over a year ago

This doesn't match the first one.

falsetru Over a year ago

@hwnd, IMHO, removing space does not make different because the log file contains space before Session.

hwnd Over a year ago

I was just letting you know =)

elahehab Over a year ago

Thanks! This one worked. Just a comment! I used matcher.group() and the result contained "A message is sent:" at beginning and "Session:" at the end. Then I changed it to matcher.group(2) and I got my result!

NGloom · Accepted Answer · 2013-12-25 10:36:37Z

0

try this pattern

"((A message is sent: )|(Message recieved:))(\\d+?)(.*)"

btw. it seems that you 'recieved' is miss matching between your log and your pattern

edited Dec 25, 2013 at 10:36

answered Dec 25, 2013 at 10:26

NGloom

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1 Comment

elahehab Over a year ago

That was a typing mistake!

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