Guillaume made another excellent suggestion to my last JavaFx/Groovy experiment, try to register the ObjectChangeListener by using an onChange property instead of addChangeListener(). In case you're wondering why it is because SwingBuilder supports adding event listeners by exposing the method names as property, i.e, button.actionPerformed = { ... }. It turns out it is not possible "out of the box" due to how JavaFX exposes an object's properties, even with the ExpandoMetaClass tweak. But we can tweak it again
// paste after previous groovy code ObjectLocation.metaClass.setOnChange = { src -> if( src instanceof Closure ) src = [onChange:src] as ObjectChangeListener if( !(src instanceof ObjectChangeListener) ) src = src as ObjectChangeListener delegate.addChangeListener(src) } /* str.addChangeListener([ onChange: { oldValue, newValue -> println "str changed from $oldValue to $newValue" } ] as ObjectChangeListener) */ str.onChange = { oldValue, newValue -> println "str changed from $oldValue to $newValue" } str.set("Java") println hw.strBut why leave it there, why not register change listeners directly to the container object instead of the attribute? sure we can, again tweaking FXObject's metaClass by adding a setOnChange() method
FXObject.metaClass.setOnChange = { String attrName, src -> delegate.attribute(attrName).onChange = src } hw.setOnChange("str") { oldValue, newValue -> println "str changed from $oldValue to $newValue" } str.set("Java") println hw.strThe result is exactly the same, we even piggybacked on the previous meta definitions of attribute() and onChange.

Keep on Groovying!