GWT native to long conversion

[Nikolay Prokofiev]

Hi.

I'm trying to convert js native number to GWT Long and send it over gwt-rpc. But I got very weird results..

public class gwtbugEntryPoint implements EntryPoint {
  @Override
  public void onModuleLoad() {
    String data = "{\"type\":\"upd\", \"id\":123}";
    ServerEvent serverEvent = JsonUtils.<ServerEvent>safeEval(data);
    RootPanel.get().add(new HTML("GWT id="+serverEvent.getId()));
  }

}
class ServerEvent extends JavaScriptObject {
    protected ServerEvent() {
    }

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

public final Long getId(){
    String idStr = _getId();
    GWT.log("idSTr:" + idStr);
    Long id = new Long(idStr);
    GWT.log("id:"+id);
    return id;
}

public final native String  _getId()/*-{ return this.id; }-*/;
}

console output:

idSTr:123

id:0

Can anyone explain me, how that could happen?

[Alberto Mancini]

Hello,

in your example you are returning  id (a numeric value) as a string ant this is the origin of the unexpected behavior.

Indeed this works

public final native String  _getIdString()/*-{ return ''+this.id; }-*/;

as well as returning a java numeric value:

public final native int  _getIdInt()/*-{ return this.id; }-*/;

(see http://www.gwtproject.org/doc/latest/DevGuideCodingBasicsJSNI.html#passing-javascript for details)

Anyway, in general, is probably not a good idea to use Long for a numeric 'native'  value  

because in js you cannot represent a long number (see f.e. http://stackoverflow.com/questions/17320706/javascript-long-integer).

Hope it helps.

    

      Alberto. 

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[Nagin Kothari]

instead of

Long id = new Long(idStr);

try

Long id = Long.parseLong(idStr);

--

Nagin Kothari
Co-founder,
Zilicus Solutions
www.zilicus.com

[Nikolay Prokofiev]

Thanks!

суббота, 1 августа 2015 г., 18:07:56 UTC-4 пользователь Alberto Mancini написал:

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