JD-Gui is an invaluable tool for troubleshooting Java applications

If you deal with Java applications, you should get familiar with JD-Gui if you aren't already. JD-Gui (Java Decompile - Graphical User Interface) does exactly what its name states, and it seems downright magical because it shows you source code from compiled Java applications, which can give you amazingly useful insight into how an application is working. Here's a screenshot of it in action, where I'm using it to look at a JAR file that's included with the IBM Control Desk ConfigTool:

All of that information came from just dropping the JAR file onto JD-Gui.

The problem I'm encountering is a SQL error complaining about a syntax error near the keyworkd "null". By looking at the trace file produced and the source code, I've been able to reproduce the exact error message, and I'm 100% confident I know exactly in the code where the error is generated. So instead of just randomly trying different possible solutions, I can focus on the very small number of areas that could be causing this particular problem.

I've been using this tool for years, so I'm not sure what took me so long to write about it.