How can you detect (from a script file) that javac found problems?

Question

The subject line says it all, but the background is:
I have a script file (.bat, since am stuck on windoze for the moment) which is doing some compilation using javac.
I would like to skip all subsequent activities in the script file after the call to javac if any file failed to compile.
So, what can I use as a signal from javac that it found a problem?
I initially tried detecting an exit code from javac that was non zero, but javac does not seem to emit such an exit coe when it objects to a file (it still returns with 0 as an exit code).
The only remaining strategy that I can think of is to pipe javac's output to a file, and if there is any content in it then assume that it indicates an error and use that as a signal.
This is suboptimal because it will give false signals for mere warnings, so if anyone has a better suggestion, please post

Answer 1

You are right: it appears that javac does exit with an exit code of 1 if an error is detected in one of the files being compiled, at least on the windows jdk.
To prove this, create an arbitrary java source file called HelloWorld.java, and create a msdos .bat file in the same directory that looks like
@echo on
javac  -Xlint:deprecation  HelloWorld.java
:handleError
@if not errorlevel 1 goto finalActions
@echo ERROR DETECTED: compile.bat will TERMINATE PREMATURELY
:finalActions
@echo compile.bat now terminatedBy playing around with what you put in the source file (totally clean code, stuff that should compile but issue a warning, and garbage that should not compile) as well as with the exit code value detected by the .bat file, for instance trying
@if not errorlevel 2 goto finalActions(see http://www.robvanderwoude.com/errorlevel.html if you need some documentation on error codes in dos bat files), I have determined the following as javac's behavior on windows:
If code is pristine, exit code = 0.
If code causes javac to emit a warning but is compilable, exit code = 0.
If code cannot be compiled, exit code = 1.