java.io.Serializable and HashMap

[Rainer Spruenken]

Hi all,

I need some help with serialization. In my app I use a custom object which contains HashMap<String, ArrayList<String>>.
When I try to tranfer this object to the server I get some serialization exception
(was not assignable to 'com.google.gwt.user.client.rpc.IsSerializable' and did not have a custom field serializer.
For security purposes, this type will not be deserialized.)
I tried to use a custom field serializer without any luck.
The Problem is that I MUST use java.io.Serializable and cannot use IsSerializable which works fine. Is there a reliable way
to use java.io.Serializable with my HashMap?


Regards and Thanke Rainer

[Maneesh Godbole]

Welcome to the Ranch.

HashMap already implements Serializable It is not the problem.
Is your custom object serializable

[Rainer Spruenken]

Thanks for your quick reply, can you please be clearer? I read a couple of threads about this topic and I think I get lost. My custom object consists of Strings, Boolean, Long and this HashMap. What do you think is wrong?

Rainer

[Maneesh Godbole]

What I meant was does your custom object implement serializable?
Let's make it easy. Show us your custom object code. (Don't forget to UseCodeTags though ;) )

[Rainer Spruenken]

Here is my object

public class Report implements Serializable {

	private String reportName;
	private String format;
	private String locale;
	private String target;
	private String fileType;
	private String dataType;
	
	private String documentName;
	private Long pageCount;
	private Long visiblePage;
	private Long requestedPage;
	private boolean pagingRequired = false;
	
	private String jobName;
	private String jobGroupName;
	private String description;

	private String owner;
	/**
	 * the parameter value map for this report
	 */
	private Map<String, List<String>> valueMap;
	/**
	 * the display value map for this report
	 */
	private Map<String, String> displayMap;
	
	//zero argument constructor
	public Report(){}

... getter and setter for member variables...

[Maneesh Godbole]

Thank you.
Can you also show us the full exception stack trace?

[Rainer Spruenken]

And here is the error message

com.google.gwt.user.client.rpc.SerializationException: Type 'xxx.xxx.xxx.Report' was not assignable to 'com.google.gwt.user.client.rpc.IsSerializable' and did not have a custom field serializer. For security purposes, this type will not be deserialized.
	at com.google.gwt.user.server.rpc.impl.LegacySerializationPolicy.validateDeserialize(LegacySerializationPolicy.java:127)
	at com.google.gwt.user.server.rpc.impl.ServerSerializationStreamReader.deserialize(ServerSerializationStreamReader.java:550)
	at com.google.gwt.user.client.rpc.impl.AbstractSerializationStreamReader.readObject(AbstractSerializationStreamReader.java:119)
	at ch.nextstride.jane.reporting.server.ReportServiceImpl.getReportRecord(ReportServiceImpl.java:175)
	at ch.nextstride.jane.reporting.server.ReportServiceImpl.doGet(ReportServiceImpl.java:144)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362)
	at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
	at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
	at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
	at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
	at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
	at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
	at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
	at org.mortbay.jetty.Server.handle(Server.java:324)
	at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
	at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:829)
	at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:513)
	at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
	at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
	at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
	at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)

[Maneesh Godbole]

Is your Report under shared?
If yes, then I cannot help further than suggesting a full clean build

[Rainer Spruenken]

the object it is not under shared...

[Maneesh Godbole]

Aha!
/client - all your UI code goes here
/server - all your server code goes here
/shared - all your data code goes here

Just refactor under shared and you should be good

[Rainer Spruenken]

ok, I will give it a try. Thanks a lot for your help. Regards Rainer

[avi sinha]

Aha!
/client - all your UI code goes here
/server - all your server code goes here
/shared - all your data code goes here

Just refactor under shared and you should be good

Maneesh!! are you sure, this is going to make a difference. whatever you have written is a convention in my opinion (I strongly agree that we all should organize classes like this in a GWT application.)
Both the client and shared packages are on the GWT client side.
There is no any difference between the client & shared packages. please correct me if i am wrong.

Thanks

[avi sinha]

Hi Rainer,

if the issue still persists, just change the Map to HashMap & List to ArrayList ( or any other implementer which you are using) and give it a try .
Providing concrete datatypes sometimes resolves the serialization issues and also enhances the performance.

Thanks

[Rainer Spruenken]

Hi, thank you for the reply, I will try using the concrete types.

Regards Rainer

[Maneesh Godbole]

avi sinha wrote:

Aha!
/client - all your UI code goes here
/server - all your server code goes here
/shared - all your data code goes here

Just refactor under shared and you should be good

Maneesh!! are you sure, this is going to make a difference. whatever you have written is a convention in my opinion (I strongly agree that we all should organize classes like this in a GWT application.)
Both the client and shared packages are on the GWT client side.
There is no any difference between the client & shared packages. please correct me if i am wrong.

Thanks

It is a convention and a good convention at that. Remember, anything (including UI and data) has to be Java<->JS translatable. By default, the GWT "compiler" is configured to pick everything under client and shared.