Adapter.java

public class Adapter {

    public String name(){
	return "god";
    }

}

AdapterFactory.java

public class AdapterFactory {

    public Adapter newAdapter(){
	return new MyAdapter();
    }
    
}

irb session

casting $ javac *java
casting $ java -cp .:$HOME/.m2/repository/org/jruby/jruby-complete/1.5.0.RC3/jruby-complete-1.5.0.RC3.jar org.jruby.Main -S irb
irb(main):001:0> require 'java'
=> true
irb(main):002:0> java_import "AdapterFactory"
=> Java::Default::AdapterFactory
irb(main):003:0> f = AdapterFactory.new     
=> #<Java::Default::AdapterFactory:0x1d8417c>
irb(main):004:0> a = f.new_adapter
=> #<Java::Default::MyAdapter:0x11fc4b8>
irb(main):005:0> a.name = "bla"
=> "bla"
irb(main):006:0> a.name
=> "bla"
irb(main):007:0> 

MyAdapter.java

public class MyAdapter extends Adapter {
    private String name;

    public void setName(String name){
	this.name = name;
    }

    public String name(){
	return name;
    }

}