No, you can't add new methods to extended class (no facility to declare
types and so on) - only overrides of super class methods.
-Sundar
On Sunday 20 July 2014 10:28 PM, Marc Downie wrote:
Does adding new methods to Java.extend based subclasses actually work?
Currently I have (staying close to the example code):
var ArrayList = Java.type("java.util.ArrayList")
var ArrayListExtender = Java.extend(ArrayList)
var printSizeInvokedArrayList = new ArrayListExtender() {
size: function() { print("size invoked!"); },
banana: function() { print("Banana"); } // this doesn't override anything
in ArrayList
}
printSizeInvokedArrayList.size() // WORKS
printSizeInvokedArrayList.banana() // TYPE ERROR ([] has no such function
"banana")
// and even:
printSizeInvokedArrayList.peach = function(){print("Peach");} // no error,
but....
printSizeInvokedArrayList.peach() // TYPE ERROR ([] has no such function
"peach")
(1.9.0-ea-b23 and 1.8.0_20-ea-b23)
Marc.
On Thu, May 1, 2014 at 11:23 PM, A. Sundararajan <
[email protected]> wrote:
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
