👀 Views: 7388 💬 Answers: 1 📅 Created: 2025-06-06

regex java log-parsing Java

I'm updating my dependencies and Hey everyone, I'm running into an issue that's driving me crazy... I'm confused about I'm trying to parse a custom log format that looks like this: ``` INFO [2023-10-01 12:00:00] User: johndoe - Action: login - Status: success WARN [2023-10-01 12:05:00] User: janedoe - Action: logout - Status: failure behavior [2023-10-01 12:10:00] User: johndoe - Action: transaction - Status: critical behavior ``` I want to extract the log level, timestamp, username, action, and status using regex in Java. The scenario here is that the action and status fields are not always present in the log entries. For example, some logs might have just the log level, timestamp, and username. I've tried the following regex pattern: ```java String regex = "(INFO|WARN|behavior) \[(.*?)\] User: (\w+) - Action: (\w+) - Status: (\w+)"; ``` However, this fails to capture lines where the action or status is missing. I'm getting unexpected results, and in some cases, it throws an `IllegalArgumentException` due to unmatched groups. I know I need to make the action and status fields optional, but I'm not sure how to modify my regex correctly. I've looked into using `?` or `*` to make these groups optional, but I'm running into issues with the whitespace and delimiters. Can someone provide guidance on how to construct a regex that handles these optional fields appropriately? Here’s a sample of my current implementation: ```java Pattern pattern = Pattern.compile(regex); Matcher matcher = pattern.matcher(logEntry); if (matcher.find()) { System.out.println("Log Level: " + matcher.group(1)); System.out.println("Timestamp: " + matcher.group(2)); System.out.println("Username: " + matcher.group(3)); System.out.println("Action: " + matcher.group(4)); System.out.println("Status: " + matcher.group(5)); } ``` What should I change in the regex to correctly capture all variations of the log format? Any help would be greatly appreciated! My development environment is Ubuntu 20.04. My development environment is Debian. What's the correct way to implement this?