"require" non-packed Java package

Ruby JRuby
1

Hello everybody,

What is a way to “require” Java package that is not packed into JAR?

From my point of view I could expect something like follow to work:

include Java
require ‘/mypath/project1/bin’
java_import ‘com.my.package.MyClass’

where project1 is something built by Eclipse or NetBeans, without
generating project1.jar each time.
Unfortunately, my guess is wrong. At least with JRuby 1.1.5.

Thanks,
Arkadi.

2

You can’t add a directory to the classpath via require(), you have to
instead do something akin to

JRuby.runtime.jruby_class_loader.addURL( … )

where the URL you add points to a directory (or a JAR).

-Bob

On Jul 29, 2010, at 9:09 AM, Arkadi K. wrote:

where project1 is something built by Eclipse or NetBeans, without

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3

On 29 Jul 2010, at 14:11, Bob McWhirter wrote:

You can’t add a directory to the classpath via require(), you have to instead do something akin to

JRuby.runtime.jruby_class_loader.addURL( … )

Try:

$CLASSPATH << ‘/path/to/my/classes’

irb(main):001:0> require ‘java’
=> true
irb(main):002:0> $CLASSPATH
=> []
irb(main):003:0> require ‘saxon9.jar’
=> true
irb(main):004:0> $CLASSPATH
=> [“file:/Users/pldms/Library/Java/Saxon/saxon9.jar”]
irb(main):005:0> $CLASSPATH << ‘classes’
=> [“file:/Users/pldms/Library/Java/Saxon/saxon9.jar”,
“file:/Users/pldms/Library/Java/Saxon/classes/”]

$CLASSPATH is magic.

Damian

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4

JRuby.runtime.jruby_class_loader.addURL( … )
Seems good enough for me.

However, the follow error is printed:
(eval):1:in include_class': cannot load Java class com.my.pkg.MyClass (NameError) from file:/C:/JRuby/jruby-1.1.5/lib/jruby.jar!/builtin/javasupport/core_ext/object.rb:38:ineval’
from
file:/C:/JRuby/jruby-1.1.5/lib/jruby.jar!/builtin/javasupport/core_ext/object.rb:67:in
include_class' from file:/C:/JRuby/jruby-1.1.5/lib/jruby.jar!/builtin/javasupport/core_ext/object.rb:38:ineach’
from
file:/C:/JRuby/jruby-1.1.5/lib/jruby.jar!/builtin/javasupport/core_ext/object.rb:38:in
include_class' from file:/C:/JRuby/jruby-1.1.5/lib/jruby.jar!/builtin/javasupport/core_ext/object.rb:81:injava_import’
from r1.rb:4

“require ‘project1.jar’” works fine with the same sources.
The sample sources are attached.

Thanks,
Arkadi.

5

$CLASSPATH << ‘/path/to/my/classes’
The $CLASSPATH << ‘/path’ part works, however the error remains the
same:
“(eval):1:in `include_class’: cannot load Java class com.my.pkg.MyClass”
and points into “java_import ‘com.my.pkg.MyClass’”.

6

After some extensive testing, the follow syntax works:
JRuby.runtime.getJRubyClassLoader.addURL(Java::java.net.URL.new(path))
java_import ‘com.my.pkg.MyClass’

However, there is an odd restriction on what “path” can be:
if it`s not JAR, it must end with “/”.
This restriction confuses, specially after reviewing Sun specification:
http://download.oracle.com/javase/6/docs/technotes/tools/windows/classpath.html

Thanks again to Bob.

7

I had run into that long ago and added it to the Wiki FAQ. Finding it
is another thing…

http://kenai.com/projects/jruby/pages/FAQs#How_come_Java_can_t_find_resources_in_class_folders_that_I_ve_appended_to_the_$CLASSPATH_global_variable_at_runtime
?

To summarize, it’s all related to Java’s URLClassLoader

This class loader is used to load classes and resources from a search
path of URLs referring to both JAR files and directories. Any URL that
ends with a ‘/’ is assumed to refer to a directory. Otherwise, the URL
is assumed to refer to a JAR file which will be opened as needed.

-lenny

8

Yeah, I hate that duality. Sometimes you need the /, sometimes you
don’t. Very confusing.

Glad you got it working. You should add something to the wiki (maybe a
FAQ, or find somewhere that talks about loading Java libs) here:

On Sun, Aug 1, 2010 at 3:06 AM, Arkadi K. [email protected]
wrote:

–
Posted via http://www.ruby-forum.com/.

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