At one point inspect also showed fields, by reflectively digging them out. Once we removed that, the inspect output is now largely useless other than showing what type the object is.

Perhaps it should be something like #<Java::SomeJavaPackage::SomeClass:0xcafebabe "toString output"> I think objections in the past were that the toString for a Java object could be very large, and inspect is often used for logging errors etc.

At one point inspect also showed fields, by reflectively digging them out. Once we removed that, the inspect output is now largely useless other than showing what type the object is.

that would make sense for me, but only doing that if there isn't a toString override (which is tricky).
should mean common types such as ArrayList or Java Date will return a simple representation (like in Ruby). large or not, there's giant inspect in Rails e.g. when you inspect a connection or smt holding it.

A simple way to do this is to just define java.lang.Object.inspect to call to_s, but that will do it for all Java objects, not just the ones that have overridden to_s.

Ok, so I thought I could do a clever trick like this:

class java::lang::Object
  alias old_inspect inspect
  def inspect
    toString
  end
  def toString
    old_inspect
  end
end

There's a couple snags though:

• I needed to comment out the default to_s impl from JavaProxyMethods.
• We do not overwrite toString in subclasses that implement it, because we always try to dispatch using the highest implementer (for various reasons, like nonpublic child classes). So this never actually uses the real toString output.

Actually ignore that first bullet; I don't think it matters. The main problem is that toString lives on exactly one Java type within JRuby: java.lang.Object. This makes it tricky to only make inspect call toString when overridden by a given class.

have an idea to play some 'ugly' tricks around and hook this up into the JavaProxy class, as I want it to play well with existing Java array inspect-ing while also providing a reflective default, we'll see how it goes ...

Ok I'll let you play with it then.

some progress - to make it somehow cleaner I would be reverting an old feature, where a proxy Java class does not get instance methods put in if its smt that exists in super hierarchy e.g. an ArrayList has a toString from AbstractCollection but the AbstractCollection.instance_methods won't include :toString since its already there on java.lang.Object ... this 'feature' is way back from fe133a2

JRuby will be shipping changed Java type inspect -> toString in 9.2.1 (#5219)