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Re: a question about creating the JAR file

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Am 26.10.2012 22:58, schrieb zyng:
> My confusion is do I need to bundle helper.jar into hello.jar? One
> thought I have is that during compiling, all the code needed from
> helper.jar has been extracted and combined into the generated *.clss
> files in build/ directory. So, for creating hello.jar, I only need to
> bundle all *.class files in build/ directory. But I am not sure that
> is correct.
> 
> Currently, I have to unjar(expand) helper.jar into build/ directory
> before I jar everything in build/. The result hello.jar works fine.
> If I skip unjarring helper.jar into build/ directory, no complain for
> creating hello.jar. But when running it, an exception of no class
> definition for a class inside helper.jar is thrown.

There are at least two ways of doing this:

1) create hello.jar (for example with ant) and embed a manifest file,
which includes helper.jar in the classpath. The good thing is: inside
the manifest, you can use relative paths. Doring java -jar hello.jar,
these paths will be resolved (AFAIK, relative to hello.jar)

2) unpack helper.jar, and include (almost) all files of helper.jar in
hello.jar. Now it's not always possible to do that, especially if you
have multiple JAR files. Some paths are reserved. For example, if you
create a StAX XML Reader, the API search the classpaths for certain
failes. Each files may contain the names of classes that implement the
StAX API. Now when you merge multiple JAR files, you would have to merge
these files as well. (This is actually a bad example, as you only want
only one StAX implementation anyways, but it illustrates the problem)
What about signed JARs?


Now method (2) has gained popularity. Probably, because "big fat JAR
plugins" for several IDEs exist (at least for Eclipse this is true).
However, I think this method should be avoided for any big application.


Regards,
  Sven

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Thread

a question about creating the JAR file zyng <xsli2@yahoo.com> - 2012-10-26 13:58 -0700
  Re: a question about creating the JAR file Lew <lewbloch@gmail.com> - 2012-10-26 14:14 -0700
    Re: a question about creating the JAR file zyng <xsli2@yahoo.com> - 2012-10-31 12:41 -0700
      Re: a question about creating the JAR file Lew <lewbloch@gmail.com> - 2012-10-31 15:19 -0700
  Re: a question about creating the JAR file Sven Köhler <remove-sven.koehler@gmail.com> - 2012-10-27 16:54 +0200
    Re: a question about creating the JAR file Jan Burse <janburse@fastmail.fm> - 2012-10-27 17:20 +0200
      Re: a question about creating the JAR file Jan Burse <janburse@fastmail.fm> - 2012-10-27 17:24 +0200
        Re: a question about creating the JAR file Sven Köhler <remove-sven.koehler@gmail.com> - 2012-10-27 19:06 +0200
    Re: a question about creating the JAR file Lew <lewbloch@gmail.com> - 2012-10-28 09:44 -0700
  Re: a question about creating the JAR file Roedy Green <see_website@mindprod.com.invalid> - 2012-11-01 18:26 -0700

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