Re: Running java programs from class files

Knute Johnson <>
Thu, 31 Aug 2006 08:29:45 -0700
Babu Kalakrishnan wrote:

Knute Johnson wrote:

So now that you solved that one, show me how to use a jar library on
the command line when I run a java program. I can make it compile but
I can't make it run. I can get it to work if I put the jar file in
the Class-Path: line in the manifest and put the jar file in the same
directory as the program jar file but not from the command line.

Test is my slightly modified class that calls a static method in
lib.Lib. The Lib class has been compiled and put into a jar file,
lib.jar in the /lib directory. I then compile from the
/test directory and run the .class file with no problems. You will
see that the lib.Lib class can't be found once I jar it.

I don't think it is possible to achieve that if you're using -jar option
of java. Once the -jar option is specified, whatever you specify as a
-classpath or -cp option is essentially ignored, and the effective user
classpath of the JVM becomes the specified jar file and the jars
specified in that jar's manifest.

An alternative would be to not use the -jar option, but to run it as :

java -cp /path_to_lib_jar/lib.jar:/path_to_test_jar/test.jar test.Test

(i.e by explicitly specifying the main class to invoke, and specifying
all the jar files in the classpath option)


I did try that and it does work just fine. I think you are correct that
you can't do what I was trying to do. See Nigel's post below.

Thanks very much Babu.


Knute Johnson
email s/nospam/knute/

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