Debug ClassCastException in client-side connector initialization

Vaadin 6 / 7 / 8
1

Hi,

I am trying to find the cause for a ClassCastException inside a Vaadin 7.2.6 application. The SuperDevMode provided me with this stacktrace:

SEVERE: java.lang.ClassCastException at Unknown.fillInStackTrace_0(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@23:3523) at Unknown.fillInStackTrace(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@10:2546) at Unknown.Throwable(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@8:2518) at Unknown.Exception(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@16:2569) at Unknown.RuntimeException(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@16:2593) at Unknown.ClassCastException(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@23:92172) at Unknown.dynamicCast(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@11:13559) at Unknown.$deserialize(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@54:36085) at Unknown.deserialize(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@15:36099) at Unknown.decodeObject(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@27:36391) at Unknown.decodeValue(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@1719:36478) at Unknown.decodeObject(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@29:36412) at Unknown.decodeValue(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@1719:36478) at Unknown.decodeIntoCollection(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@23:36355) at Unknown.decodeList(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@8:36362) at Unknown.decodeValue(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@1719:36478) at Unknown.decodeObject(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@29:36412) at Unknown.decodeValue(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@1719:36478) at Unknown.$updateConnectorState(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@14:28264) at Unknown.execute_22(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@34:28369) at Unknown.endDependencyLoading(http://localhost:9876/vaadin.AppWidgetSet/5601E60412064200647F380440CB4188.cache.js@11:26393) ... So it seems some state object cannot be deserialized correctly in the Javascript-version of ApplicationConnection.java.

How can I find out which object is causing this? I tried activating the profiler to get a bit more information about which connector blows up, but I can’t see any profiler messages in the Javascript/Debug console, besides this:

com.vaadin.client.Profiler SEVERE: Got end event for updateConnectorState but is currently in JsonDecoder.decodeObject What is the best way to see what data causes the exception? My Javascript debugging skills are a bit lacking… Inside the Chrome debugger all the interesting values seem to be undefined when stepping through updateConnectorState.

Any hints are greatly appreciated!

2

Ok, using Chrome instead of Chrome Portable helps a lot with debugging…

So the ClassCastException occurs when calling this:

return new ju.Date_3(fromDouble(cggjc.$doubleValue([b] dynamicCast(jsonValue, 126) [/b]))) where jsonValue is an Object describing a date (see attachment). This is in the Date_Serializer which expects a number, but receives an Object.

It seems the serialization of the date doesn’t turn the date into a number?

16729.png

3

The JSON received from the server indeed contains an object instead of a number:

{..., "bandInfos":[{"date":{"date":1,"hours":0,"seconds":0,"month":6,"year":114,"minutes":0,"time":1404165600000}, ...}]
, ...}

Any ideas?
Cheers!

4

Alright, I found the culprit.

The “date” in the state came directly from a database… turns out it isn’t a java.util.Date but a java.sql.Timestamp.

The customSerializers in
https://github.com/vaadin/vaadin/blob/cf77a27c7f711e076c4f2c47cca46d87111bdb15/server/src/com/vaadin/server/JsonCodec.java#L217

expect an actual Date, not a subclass.

Would be great if you can make it work for subclasses as well, because currently the behavior is quite unexpected.

5

Atleast it should handle the common subclasses java.sql.Date and Timestamp or minimally, when not compiled for production, serialization should throw an error.