ioannis cherouvim

Imagine the following scenario:

• you are trying to trace a bug in an old, ugly and improperly constructed legacy application (you know… the application with the 2kloc classes containing 14 nested ifs)
• access to a debugger is not possible but you can recompile one or more classes and restart the server
• you need to find who is calling a particular method, but don’t want to insert one thousand print messages in the one thousand places where the method is being called from
• doing it with AOP gives you a headache

If all the above are true, then maybe the only hope is placing the following line in the beginning of the method in question:

System.out.println("called from: " + 
            new RuntimeException().getStackTrace()[1]);

Yes, this is ugly but it does the job. As the application is running it will print traces such as:

called from: com.spaghetti.backend.LoginAction.execute(LoginAction.java:3689)
called from: com.spaghetti.backend.LaunchMissilesAction.execute(LaunchMissilesAction.java:1062)
called from: com.spaghetti.StringHelper.getTime(StringHelper.java:501)
called from: com.spaghetti.TimeUtils.capitaliseString(TimeUtils.java:1723)

Good luck, and don’t forget to remove the print statement before committing. You don’t want the next maintainers to freak out ;)

This entry was posted on Friday, October 22nd, 2010 at 18:25 and is filed under hacks, java. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.