Wednesday, July 27, 2016

Re: using Generics in GWT JsInterop: Uncaught java.lang.ClassCastException

Thanks for your suggestion. SNAPHOT did resolve this error, but caused others. I ended up using JSNI and the cast() method of the JavaScriptObject. 

@JsFunction  public interface Function{      public JavaScriptObject call(JavaScriptObject event);    }

@JsType  public class MouseEvent extends JavaScriptObject {  	      protected MouseEvent(){}

   public final native  String getType() /*-{  	return;      }-*/;


and then: 
map.on("click", new Function(){          @Override          public JavaScriptObject call(JavaScriptObject event) {

          MouseEvent msEvent = event.cast();        });

This is the only workaround I found for now, although I would have prefered to use JsInterop only. Hoping that the stable release will correct this issue. 

Le mardi 26 juillet 2016 17:07:00 UTC+2, Thomas Broyer a écrit :

On Tuesday, July 26, 2016 at 4:45:03 PM UTC+2, zakaria amine wrote:

I have an interface annotated with @JsFunction that I use as a callback for events. As there are different types of events, I have added a type parameter:

@JsFunction  public interface Function<T extends Event>{      public JavaScriptObject call(T event);    }

From the entry point I do something like :

//...    map.on("click", new Function<MouseEvent>(){          @Override          public JavaScriptObject call(MouseEvent event) {        });

When I run the project, everything compiles and run fine. But when the code above is executed, I get the following exception in the console:

Uncaught java.lang.ClassCastException                              

This seems like a GWT internal error. Is this a known bug in GWT 2.8 ? Are generics not allowed with JsInterop types?

Many things have changed since 2.8.0-beta1, have you tried with 2.8.0-SNAPSHOT? (I'm not saying it will work, I'm saying one shouldn't draw conclusions based on beta1)

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