Monkey patching a Java class?

[A. Sundararajan]

No, you can't add/remove a method (or public field) of a Java class to 
use within the script. You could subclass and expose that subclass as 
"java.io.File" by

     var oldFile = java.io.File;
     java.io.File = Java.extend(oldFile, ...)

But, I'd not recommend it - besides user can still get original 
java.io.File via Java.type (unless you do similar hack on Java.type as 
well!!)

Cleaner approach is to expose a script API wrapping java.io.File.

-Sundar

On Thursday 17 April 2014 12:03 AM, HRJet wrote:
> Is it possible to monkey patch a Java class for use within Javascript?
>
> For example, I want to add a convenience method to java.io.File class, say
> "readAsString()".
>
> Then, in javascript I want to call file.readAsString()  where file is an
> instance of java.io.File. Note that the file instance may be created by
> some third-party code, over which I have no control.
>
> In Java land, this seems to be usually done with CGLib or AspectJ, etc.
>
> I was wondering if nashorn had some trick up its sleeve for doing this in
> script land, since this sort of thing is common in Javascript.
>
> thanks,
> HRJ