On Sunday, October 19, 2014 1:46:42 AM UTC+2, Magnus wrote:
>
> Hi,
>
> I want to define a hover handler in Java and reference it from JavaScript
> in order to register it in a JS library:
>
> But the reference causes an error:
>
> public class MyClass
> {
> public native void myHandler (JavaScriptObject e) // don't know if
> JavaScriptObject is the right type
>
>
You could also use com.google.gwt.dom.client.NativeEvent (and wouldn't need
JSNI).
> /*-{
> var c = e.target.className;
> console.log (c);
> }-*/;
>
> private native void startHover (String stl_w)
> /*-{
> var f = [email protected]::myhandler; // produces syntax error
>
>
Should be
[email protected]::myHandler(Lcom/google/gwt/core/client/JavaScriptObject;),
or [email protected]::myHandler(*), or just this.@myWidget::myHandler(*)
in GWT 2.7 (resolves class names relative to package and imports).
>
> $wnd.myLib.hover (f); // register handler in the external library
>
>
That won't work the way you expect it to, because the 'this' inside
myHandler won't be an instance of MyClass/myWidget.
Exceptions occurring inside myHandler also won't be dispatched to
GWT.UncaughtExceptionHandler, and scheduled commands (scheduleEntry, and
scheduleFinally within myHandler) won't work; for that you need to wrap the
function with $entry: f = $entry(f).
This would work best:
var self = this;
$wnd.myLib.hover($entry(function(e) { self.@myWidget::myHandler(*)(e); }));
To sum up: your errors here are related to JSNI method reference syntax,
and scope and 'this' in JavaScript.
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