在zxing core.jar文件中找不到MultiFormatReader类

Question

I'm trying to use a more current version of zxing and have tried replacing the core.jar and javase.jar files from the ecin/zxing gem with the 3.0 snapshot versions of those files from https://oss.sonatype.org/content/repositories/snapshots/com/google/zxing/core/

I'm getting a NameError on the first class I try to reference ( com/google/zxing/MultiFormatReader from the core.jar file) even though the class shows up in the new jar when I do a jar -tf . The software runs file with the old jar files.

Any suggestions on how to debug this further?

Update : I created a new gemset with a Gemfile with only zxing in it and reproduced the same behavior, as shown below.

MacbookAir1:javlats2 palfvin$ irb
jruby-1.7.10 :001 > require 'zxing'
NameError: missing class or uppercase package name (`com.google.zxing.MultiFormatReader')
    from org/jruby/javasupport/JavaUtilities.java:54:in `get_proxy_or_package_under_package'
    from file:/Users/palfvin/.rvm/rubies/jruby-1.7.10/lib/jruby.jar!/jruby/java/java_package_module_template.rb:14:in `method_missing'
    from /Users/palfvin/.rvm/gems/jruby-1.7.10@javlats2/gems/zxing-0.3.1/lib/zxing/decoder.rb:12:in `ZXing'
    from /Users/palfvin/.rvm/gems/jruby-1.7.10@javlats2/gems/zxing-0.3.1/lib/zxing/decoder.rb:3:in `(root)'
    from org/jruby/RubyKernel.java:1083:in `require'
    from /Users/palfvin/.rvm/rubies/jruby-1.7.10/lib/ruby/shared/rubygems/core_ext/kernel_require.rb:1:in `(root)'
    from /Users/palfvin/.rvm/rubies/jruby-1.7.10/lib/ruby/shared/rubygems/core_ext/kernel_require.rb:55:in `require'
    from org/jruby/RubyKernel.java:1083:in `require'
    from /Users/palfvin/.rvm/gems/jruby-1.7.10@javlats2/gems/zxing-0.3.1/lib/zxing.rb:2:in `(root)'
    from /Users/palfvin/.rvm/rubies/jruby-1.7.10/lib/ruby/shared/rubygems/core_ext/kernel_require.rb:1:in `(root)'
    from org/jruby/RubyKernel.java:1119:in `eval'
    from /Users/palfvin/.rvm/rubies/jruby-1.7.10/lib/ruby/shared/rubygems/core_ext/kernel_require.rb:135:in `require'
    from (irb):1:in `evaluate'
    from org/jruby/RubyKernel.java:1519:in `loop'
    from org/jruby/RubyKernel.java:1282:in `catch'
    from org/jruby/RubyKernel.java:1282:in `catch'
    from /Users/palfvin/.rvm/rubies/jruby-1.7.10/bin/irb:13:in `(root)'jruby-1.7.10 :002 > 

Answer 1

This session worked from IRB, so the class is present in the new version of the JAR:

> require 'core-3.0.0-20140213.213916-7.jar'
> com.google.zxing.MultiFormatReader.new
 => #<Java::ComGoogleZxing::MultiFormatReader:0x6e644f41>

My guess is that you haven't replaced the JAR in the right way, somehow. I did this to "upgrade" the JAR:

pushd ~/.rvm/gems/jruby-1.7.10/gems/zxing-0.3.1/lib/zxing/
mv core.jar orig.jar
mv ~/Downloads/core-3.0.0-20140213.213916-7.jar core.jar

Then was able to do this:

> require 'zxing'
> ZXing.decode 'http://2d-code.co.uk/images/bbc-logo-in-qr-code.gif'
 => "http://bbc.co.uk/programmes"

I don't know the difference between the 2.x and 3.x APIs to be sure, but I can certainly drop in the new JAR over the old one.

Answer 2

I turns out this was related to the version of Java pointed to by my PATH variable. Even though I'd long ago installed version 7 on my mac, I'd never updated my .bash_profile and was picking up 6 for various command line operations. After I changed my PATH to point to 7, the problem went away.

There are still a few mysteries that remain, however, as follows:

• When I posted my question, there were jar files in the zxing snapshot directories named ( -6.jar ) as if they were built for version 6, but they are no longer there (less than 24 hours later)
• When I tried those -6.jar files, they failed as well
• I can't find anything on the web about general incompatibility between Java 6 and Java 7 that would explain the error I was getting