Is it possible to convert an anonymous class from Java to JRuby?

Question

I am working on implementing a JRuby wrapper around the SNMP4J-Agent library, found here:

Website: http://www.snmp4j.org/
JavaDocs: http://www.snmp4j.org/agent/doc/

It's been pretty fun so far, but I am having trouble deciphering the following piece of Java code to implement in JRuby:

server = new DefaultMOServer();
vacmMIB = new VacmMIB(new MOServer[] { server });

The problem is that - as far as I can tell - casting new with MOServer[] (which is an interface) creates an anonymous function that is passed a server object, and I can't seem to find the right way to express that with JRuby. I've included information about the Java classes:

DefaultMOServer is defined as

public class DefaultMOServer implements MOServer {
    public DefaultMOServer() {
       ...
    }
    ...
}

JavaDoc: http://www.snmp4j.org/agent/doc/org/snmp4j/agent/DefaultMOServer.html

VacmMIB is defined as

public class VacmMIB implements MOGroup, MutableVACM {
    public VacmMIB(MOServer[] server) {
       this.server = server;
       ...
    }
    ...
}

JavaDoc: http://www.snmp4j.org/agent/doc/org/snmp4j/agent/mo/snmp/VacmMIB.html

And finally, MOServer is defined as

public interface MOServer {
   ...
}

JavaDoc: http://www.snmp4j.org/agent/doc/org/snmp4j/agent/MOServer.html

Here is roughly what I am doing in JRuby:

require 'java'
require 'snmp4jruby'
require 'lib/snmp4j-agent-1.4.3.jar'

module Agent
    include_package 'org.snmp4j.agent'

    module MO
       include_package 'org.snmp4j.agent.mo'

       module SNMP
          include_package 'org.snmp4j.agent.mo.snmp'
       end
    end
end

class SnmpAgent < Agent::BaseAgent

    # Setup the agent
    def init
       ... everything works fine up here ...

       # Server is created early on without issue
       self.server = Agent::DefaultMOServer.new

       # Having trouble here
       _server = Agent::MOServer.new { self.server }
       self.vacmMIB = Agent::MO::SNMP::VacmMIB.new(_server)
    end

end

Running the above code gives me the following error for the line where I set self.vacmMIB = ...:

TypeError: failed to coerce org.jruby.gen.InterfaceImpl792882806 to [Lorg.snmp4j.agent.MOServer;

Any direction on this would be greatly appreciated!

Answer 1

Your issue seems to be that VacmMIB constructor takes array of MOServer as an argument and you're passing an instance of MOServer.

Try this:

_server = Agent::MOServer.new { self.server }
# your code
# self.vacmMIB = Agent::MO::SNMP::VacmMIB.new(_server) 
# updated code
self.vacmMIB = Agent::MO::SNMP::VacmMIB.new([_server])