3. Launch BlueJ.   From the Help menu,
select "Installed
Extensions".  You should see
Compile Logger in the list.  Click on the question mark bubble
for this entry; the Extension Details dialog should
appear. Locate the name of the file to which compile events are
logged.  By default, events are logged to 
bluej-compilelog.txt in the 
.bluej folder of your home
directory. 
Using Compile Logger
  - Every time you compile a program within BlueJ, the Compile Logger
extension logs the event data, storing the time and whether the compile
was successful or not. 
- When you exit BlueJ, the data is appended to the log file. By
default, the log file is 
 bluej-compilelog.txt
in the .bluej folder of
your home directory.
- You may specify a different location for the log file.  From
the Tools menu select Preferences, then click the Extensions tab. 
Under Compile Logger Extension, there is a text field in which you
modify the name of the compile logfile.
 
- The log is not written until you properly exit Bluej, so if your
machine
slows down on you in the middle of a run and you end up killing the
Bluej process the log will not be written.
-  Always exit BlueJ normally -- that is dont just log out of your
account on a lab machine with BlueJ still open. 
Sample log file
2008.03.30 13:41:14 Compile Started (1 file) HelloWorld.java
... compile succeeded.
2008.03.30 13:41:23 Compile Started (1 file) HelloWorld.java
Compile Error: line 10 ';' expected
... compile failed.
2008.03.30 13:41:26 Compile Started (1 file) HelloWorld.java
... compile succeeded.
2008.03.30 13:41:34 Compile Started (3 files)
HelloWorld.java,HiWorld.java,ByeWorld.java
... compile succeeded.
Summary Script
Here is a simple 
bash script that
will summarize the data in a log file.