Add *.jars to *.jars possible/recommendend? Eclipse setup for this?

[Ulf Meinhardt]

Assume I want to create a new program and to pack everything into a *.jar archive.
To run the program one (or more) additonal external *.jar is required.

Ok, the potential user could install the two *.jar files independently and add them
to his CLASSPATH. This is somehow uncomfortable. I would like to deploy/provide simply one
*.jar with everything needed inside.

So I have to add the second, external jar into the "main" first jar as well.

Is this procedure possible/unusual/recommended?

How do I do this from the command line ?

How do I tell Eclipse to not only reference the external *.jar lib but ADD them physically
into the target *.jar?

As far as I know simply adding them on the Properties->Java Build Path->Libraries dialog
does NOT automatically add them into the target *.jar but only references it.

Ulf

 

[Nigel Wade]

On Wed, 03 Feb 2010 11:17:16 +0000, Ulf Meinhardt wrote:

Don't multi-post. I've just realized this has already been answered in
the other NG.

Assume I want to create a new program and to pack everything into a
*.jar archive. To run the program one (or more) additonal external *.jar
is required.

Ok, the potential user could install the two *.jar files independently
and add them to his CLASSPATH. This is somehow uncomfortable. I would
like to deploy/provide simply one *.jar with everything needed inside.

So I have to add the second, external jar into the "main" first jar as
well.

Is this procedure possible/unusual/recommended?
yes/yes/no.


How do I do this from the command line ?

You could add the dependant jar to the main jar using jar:

jar -uf main.jar other.jar

However, other.jar will not be visible to the class loader. For the class
loader to be able to use it it would have to be extracted from main.jar
first.

It is actually simpler to package both jars into some other archiving
container (zip, tar or even jar). Then unpack that to create the
necessary structure.

If, for example, the manifest of main.jar contains
Class-Path: lib/other.jar

then the contents of the archive would be
main.jar
lib/other.jar

when extracted it should create the same disk structure.

The manifest in main.jar will allow the class loader to find
lib/other.jar. The path in the manifest is relative to the location of
the executing jar, not the current directory.

How do I tell Eclipse to not only reference the external *.jar lib but
ADD them physically into the target *.jar?

As far as I know simply adding them on the Properties->Java Build
Path->Libraries dialog does NOT automatically add them into the target
*.jar but only references it.

I don't use Eclipse.

 

[Lew]

Don't multi-post. I've just realized this has already been answered in
the other NG.
!

It is actually simpler to package both jars into some other archiving
container (zip, tar or even jar). Then unpack that to create the
necessary structure.

If, for example, the manifest of main.jar contains
Class-Path: lib/other.jar

then the contents of the archive would be
main.jar
lib/other.jar

when extracted it should create the same disk structure.

The manifest in main.jar will allow the class loader to find
lib/other.jar. The path in the manifest is relative to the location of
the executing jar, not the current directory.

You can best do this with Ant.


Don't. Do what Nigel said, or just pack the main and auxiliary JARs together
in a directory and associated subdirectories that get copied to the
application root directory.

Words to the wise:

JAR files are nearly complete vehicles for application delivery, combining
features of ZIP with Java intelligence to know how to run the application.
The "java" command has an option "-jar" that tells Java to run the program
from the JAR file ("main.jar" in Nigel's example). Use of the "-jar" option
suppresses all other classpath options and takes the classpath entirely from
the (main) JAR manifest.

The easiest, best, and most commonly used layout is what Nigel suggested, with
the main JAR in the application directory and the library JARs on which it
relies in the same directory or the "lib/" subdirectory thereof, as specified
in the manifest. Do not use absolute paths or parent directory ("../") paths
for the libraries.

No more multiposting, now that you know.