Martin Kleppmann created JRUBY-6635:
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Summary: Java superclass method is not visible to JRuby
Key: JRUBY-6635
URL: https://jira.codehaus.org/browse/JRUBY-6635
Project: JRuby
Issue Type: Bug
Components: Java Integration
Affects Versions: JRuby 1.6.7
Environment: Mac OS X 10.7.3
Java(TM) SE Runtime Environment (build 1.6.0_31-b04-415-11M3635)
Java HotSpot(TM) 64-Bit Server VM (build 20.6-b01-415, mixed mode)
Reporter: Martin Kleppmann
In some specific circumstances, methods defined on Java classes are not
callable from JRuby. I have observed this happening when the following things
come together:
* the instantiated class is a subclass of another Java class,
* the superclass has default visibility,
* the superclass has a generic type parameter, and
* a method is defined on the superclass whose return type is the generic type
parameter.
In these circumstances, JRuby thinks that this method does not exist. (It's
particularly curious that if the method has a non-generic return type, the
method *is* callable from JRuby!)
Example, using JRuby installed via Maven:
{noformat}
$ cat Superclass.java
class Superclass<T> {
private T proto;
public T getProto() { return proto; }
}
$ cat Subclass.java
public class Subclass extends Superclass<String> {}
$ javac Superclass.java Subclass.java
$ java -cp
.:$HOME/.m2/repository/org/jruby/jruby-complete/1.6.7/jruby-complete-1.6.7.jar
org.jruby.Main -S irb
irb(main):001:0> java_import Java::Subclass
=> Java::Default::Subclass
irb(main):002:0> Subclass.new.proto
NoMethodError: undefined method `proto' for
#<Java::Default::Subclass:0x622f996f>
from (irb):2:in `evaluate'
from org/jruby/RubyKernel.java:1083:in `eval'
from
file:/Users/martin/.m2/repository/org/jruby/jruby-complete/1.6.7/jruby-complete-1.6.7.jar!/META-INF/jruby.home/lib/ruby/1.8/irb.rb:158:in
`eval_input'
from
file:/Users/martin/.m2/repository/org/jruby/jruby-complete/1.6.7/jruby-complete-1.6.7.jar!/META-INF/jruby.home/lib/ruby/1.8/irb.rb:271:in
`signal_status'
from
file:/Users/martin/.m2/repository/org/jruby/jruby-complete/1.6.7/jruby-complete-1.6.7.jar!/META-INF/jruby.home/lib/ruby/1.8/irb.rb:155:in
`eval_input'
from org/jruby/RubyKernel.java:1410:in `loop'
from org/jruby/RubyKernel.java:1183:in `catch'
from
file:/Users/martin/.m2/repository/org/jruby/jruby-complete/1.6.7/jruby-complete-1.6.7.jar!/META-INF/jruby.home/lib/ruby/1.8/irb.rb:154:in
`eval_input'
from
file:/Users/martin/.m2/repository/org/jruby/jruby-complete/1.6.7/jruby-complete-1.6.7.jar!/META-INF/jruby.home/lib/ruby/1.8/irb.rb:71:in
`start'
from org/jruby/RubyKernel.java:1183:in `catch'
from
file:/Users/martin/.m2/repository/org/jruby/jruby-complete/1.6.7/jruby-complete-1.6.7.jar!/META-INF/jruby.home/lib/ruby/1.8/irb.rb:70:in
`start'
from /Users/martin/Applications/jruby/bin/jirb:13:in `(root)'
{noformat}
The same exception occurs when trying to call {{get_proto}} or {{getProto}}.
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