When you are working on a problem (or enhancement) of Oracle Apps it can be useful from time to time to know which version of a java .class file you have on your system. .class is a compiled .java file so you can not simply look into the code by executing a cat or head command on the prompt. You could try to decompile the .class file however when java is compiled all the comments are stripped, meaning that if you decompile the .class file you will not be able to find any comments of the version in it.
Because Oracle itself is also needing this information, especially when you are logging a SR (TAR) on metalink it can come in handy for Oracle Support that they can pinpoint a file and request the version of it. Therefor Oracle has included the adident utility in its AD Utility package.
You can now get the version by executing the adident command. For example I do get the information about the RTFTextParser.class class file here by executing this command:
[root@testserver /]# adident Header RTFTextParser.class
$Header RTFTextParser.java 115.25 2006/11/09 23:52:22 bgkim noship