JRuby Java File class error message

I get the following error messages some times when running JRuby scripts:

C:\Al\RobotWork\TestPlayer>jruby ScreenCapture.rb
/jruby-0_9_2/src/builtin/javasupport.rb:359:in matching_method: no
method 'read' with arguments matching [org.jruby.RubyFile] (NameError)
        from /jruby-0_9_2/src/builtin/javasupport.rb:113:in `setCacheDirectory'
        from /jruby-0_9_2/src/builtin/javasupport.rb:72:in `read'
        from ScreenCapture.rb:20:in `open_image_file'
        from ScreenCapture.rb:26

This always happens when I try to include the Java File class into my jruby scripts, like this:

include_class 'java.io.File'

I think what's happening is that my reference to a File object in my jruby code is ambiguous. The interpreter can't figure out whether I'm referring to the Java File class, or the Ruby File class.

What I do to get around this is explicitly reference the Java File class in my JRuby programs, something like this:

f = java.io.File.new("Foo.txt")

That's a pretty lame example, but hopefully you get the idea.