Test of JRuby/Java reflection

A.java

public class A {
  public void hello() {
    System.out.println("hello from A");
  }
}

B.java

public class B {
  public static void hello() {
    System.out.println("hello from B");
  }
}

C.java

public class C {
  public static void hello() {
    System.out.println("hello from C");
  }
}

Caller.java

import java.lang.reflect.Method;

public class Caller {
  public static void main(String args[]) {
    callbackTest(args[0]);
  }

  static void callbackTest(String classname) {
    System.out.println("args = " + classname);
    try {
      Class c = Class.forName(classname);
      System.out.println("class = ");
      System.out.println(c);
      Object o = c.newInstance();
      Method m = c.getMethod("hello");
      m.invoke(null);

    } catch(Exception e) {
      System.out.println("failed to invoke class method");
      System.out.println(e);

      try {
        Class c2 = Class.forName(classname);
        Object o2 = c2.newInstance();
        Method m2 = c2.getMethod("hello");
        m2.invoke(o2);
      } catch(Exception e2) {
        System.out.println("failed to invoke object method");
        System.out.println(e2);
      }
    }
  }
}

caller_test.rb

require "caller.jar"
java_import "MyCallback"

require "jruby/core_ext"

class MyCallbackLocal
  def hello
    puts "hello from MyCallbackLocal"
  end
end
MyCallbackLocal.become_java!

puts "trying with class inside jar"
Java::Default::Caller.callbackTest("A")

puts "trying with class outside jar"
Java::Default::Caller.callbackTest("C")

puts "trying with JRuby class that is compiled to .class with jrubyc"
Java::Default::Caller.callbackTest("MyCallbackJrubyc")

puts "trying with JRuby class that is compiled to .java with jrubyc and .class with javac"
Java::Default::Caller.callbackTest("MyCallbackJrubycJavac")

puts "trying with JRuby class defined locally"
Java::Default::Caller.callbackTest("MyCallbackLocal")

MyCallbackJrubyc.rb

class MyCallbackJrubyc
  def hello
    puts "hello from MyCallbackJrubyc"
  end
end

MyCallbackJrubycJavac

class MyCallbackJrubycJavac
  def hello
    puts "hello from MyCallbackJrubycJavac"
  end
end

output

trying with class inside jar
args = A
class = 
class A
failed to invoke class method
java.lang.NullPointerException
hello from A
trying with class outside jar
args = C
class = 
class C
hello from C
trying with JRuby class that is compiled to .class with jrubyc
args = MyCallbackJrubyc
class = 
class MyCallbackJrubyc
failed to invoke class method
java.lang.NoSuchMethodException: MyCallbackJrubyc.hello()
failed to invoke object method
java.lang.NoSuchMethodException: MyCallbackJrubyc.hello()
trying with JRuby class that is compiled to .java with jrubyc and .class with javac
args = MyCallbackJrubycJavac
class = 
class MyCallbackJrubycJavac
failed to invoke class method
java.lang.NullPointerException
hello from MyCallbackJrubycJavac
trying with JRuby class defined locally
args = MyCallbackLocal
failed to invoke class method
java.lang.ClassNotFoundException: MyCallbackLocal
failed to invoke object method
java.lang.ClassNotFoundException: MyCallbackLocal