FULL PRODUCT VERSION :
Bug seen on OS X + Linux 64 with both 1.8.0_20-ea-b23 and 1.9.0-ea-b23

ADDITIONAL OS VERSION INFORMATION :
Bug seen on OS X (10.9) + various Linux 64 with both 1.8.0_20-ea-b23 and 1.9.0-ea-b23

A DESCRIPTION OF THE PROBLEM :
Placing a reference to a bound java method into a javascript variable then calling it is not equivalent to calling it directly

var ArrayList = Java.type("java.util.ArrayList")
al = new ArrayList()
al.size() // WORKS
var size = al.size
size() // ClassCastException

java.lang.ClassCastException: Cannot cast jdk.nashorn.internal.runtime.Undefined to java.util.ArrayList
at java.lang.invoke.MethodHandleImpl.newClassCastException(MethodHandleImpl.java:312)
at java.lang.invoke.MethodHandleImpl.castReference(MethodHandleImpl.java:307)
at jdk.nashorn.internal.scripts.Script$Recompilation$514$\^eval\_.:program(bx<Untitled>:2)
at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:567)
at jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:222)
at jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:376)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:465)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:429)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:425)
at jdk.nashorn.api.scripting.NashornScriptEngine.eval(NashornScriptEngine.java:158)

Whereas with a pure JavaScript object, it works as expected:

Foo = function(){}
Foo.prototype.banana = function(){print("BANANA");}
foo = new Foo()
foo.banana() // WORKS
f = foo.banana
f() // WORKS

It seems that there isn't anything that one can actually legally do with a reference to al.size other than toString it. This is unexpected, but if it is to be the case, a better and more descriptive exception than a ClassCastException would be helpful.



REPRODUCIBILITY :
This bug can be reproduced always.