How do I pipe the Java console output to a file?

Question

I found a bug in an application that completely freezes the JVM. The produced stacktrace would provide valuable information for the developers and I would like to retrieve it from the Java console. When the JVM crashes, the console is frozen and I cannot copy the contained text anymore.

Is there way to pipe the Java console directly to a file or some other means of accessing the console output of a Java application?

Update: I forgot to mention, without changing the code. I am a manual tester.

Update 2: This is under Windows XP and it's actually a web start application. Piping the output of

javaws jnlp-url

does not work (empty file).

Answer 1

(If you can modify the code) you can set the System.out field to a different value:

System.out = new PrintStream(new FileOutputStream(fileName));

If you are running a script (invoking the program via java) from Unix you could do:

/path/to/script.sh >& path/to/output.log

Answer 2

A frozen console probably means a deadlock (it could also mean repeated throwing of an exception). You can get a stack dump using jstack. jps may make finding the process easier.

Answer 3

Actually one can activate tracing in the Java Control Panel. This will pipe anything that ends up in the Java console in a tracing file.

The log files will end up in:

• <user.home>/.java/deployment/log on Unix/Linux
• <User Application Data Folder>\Sun\Java\Deployment\log on Windows

Answer 4

When I found a crash in a Java application I tried to get some help from the above thread (which started a year ago). In my case I run GeoGebra.exe (from GeoGebra.org) and the program crashes (total freeze-up) when I either Apply Ctrl-C to a dialog used for renaming a label, or when I apply Ctrl-C to any line in the Java console. I have examined the log files in Application Data/Sun/deployment/log, but there is nothing added to these when the crash occurs. I suspected at first a fault in XP, but a repair re-install makes no difference. I guess there is a bug in the program (doubtful) or some crazy conflict with something else.

Has anyone any real solution to this issue ?

On Vista there is no problem !