Passing ArrayList to Ruby as a RubyArray

Question

In Ruby, if you do something like

print ["Hello", 1, 2]

You get an output like

["Hello" , 1 , 2]

Have some ArrayList object, list in Java. It contains objects of type Object.

I am passing this list to my Ruby code. When you print this, the console outputs something like

<Java::JavaUtil::ArrayList:0x5ab077a7>

Which is correct, of course.

However, I would like to get the same behaviour as above. If list contains two objects of type Object, when Ruby pints it, I want to get

[Object:0x1234567 , Object:0x21432423]

Rather than the reference of the list itself.

I suspect I should convert list to RubyArray before passing it to Ruby. But how?

kares · Accepted Answer · 2014-06-09 09:44:35Z

2

if you look at the API of org.jruby.RubyArray you'll find a newArray factory method :

java.util.ArrayList list = new java.util.ArrayList();
org.jruby.RubyArray array = org.jruby.RubyArray.newArray(runtime, list);

of course you need to have a reference to a org.jruby.Ruby runtime which from the Java side (depending on your usage scenario) might be obtained in a few ways :

org.jruby.Ruby.getGlobalRuntime();
org.jruby.Ruby.getThreadLocalRuntime();

also note, having a runtime instance there's several "helper" factory methods that create ruby objects in Java e.g. org.jruby.Ruby.getGlobalRuntime().newArray(list)

answered Jun 9, 2014 at 9:44

kares

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