Gwt - How can I "cast" a overlay (JavaScriptObject) into a real Java object?

Question

In my GWT project, I really need to implement the same interface between several overlays (JavaScriptObject).

According to the documentation :

Starting with GWT 2.0, it is permissible for JavaScriptObject subtypes to implement interfaces. Every method defined in an interface may map to at most one method declared in a JavaScriptObject subtype. Practically speaking, this means that only one JavaScriptObject type may implement any given interface, but any number of non-JavaScriptObject types may also implement that interface.

So, I would like to "cast" my JavaScriptObject to a real Java object. It allows me to reduce considerably a lot of duplication code.

Is it possible ? Thanks.

pistolPanties · Accepted Answer · 2011-08-11 11:15:38Z

1

How about creating classes that wrap a JSO instead of inherting it?

public class PersonJso extends JavaScriptObject{
    protected PersonJso() {}
    public static native PersonJso create(String name) /*-{
        return {name : name};
    }-*/;
    public final native String getName() /*-{
        return this.name;
    }-*/;
}

public class AnimalJso extends JavaScriptObject{
    protected AnimalJso() {}
    public static native PersonJso create(String name) /*-{
        return {name : name};
    }-*/;
    public final native String getName() /*-{
        return this.name;
    }-*/;
}
public class AnimalWrapper implements hasName{
    AnimalJso jso;
    public AnimalWrapper(){}
    public AnimalWrapper(AnimalJso jso){
        this.jso = jso;
    }
    @Override
    public String getName() {
        return jso.getName();
    }
}
public class PersonWrapper implements hasName{
    PersonJso jso;  
    public PersonWrapper(){}
    public PersonWrapper(PersonJso jso){
        this.jso = jso;
    }
    @Override
    public String getName() {
        return jso.getName();
    }   
}

answered Aug 11, 2011 at 11:15

pistolPanties

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2 Comments

Sandro Munda Over a year ago

yeah, I think that it's a solution but I have to write a lot of wrappers (exactly the double !). Do you think that it's the unique solution ?

pistolPanties Over a year ago

I guess another workaround could be to add methods which you intend to use as interfaces with empty bodies and create a CustomJSO. Then you reproduce your JSO's to extend CustomJSO.That way you can write a single wrapper that wraps any of your JSO's as CustomJSO so that your wrapper can implement any interface which includes methods that you already have added to your CustomJSO.

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