I have a jar file with source code packed.
i inserted the jar in war/WEB-INF/lib/xxx.jar Add to build path
but when i run the project i got an error
If you want to include external jar to GWT then make sure you did the following
Eg. if you have a package in jar named "sample.source" and your .gwt.xml file in jar is "Source.gwt.xml" and this .gwt.xml file in "sample" folder and classes or entities in "source" folder
Then your current project must inherits it. ie it must have the following tag
<inherits name='sample.Source'/>
Eg : Sorce.gwt.xml in jar file
<module>
<source path="">
<include name="**/MyEntity.java"/>
</source>
</module>
For reference :http://jonathan.lalou.free.fr/?p=1077
GWT is not supporting serialization in client side so try to use RPC and use these classes from jar in server or you just copy the packages of jar and add to src of gwt project.
OR
I solved the problem the jar files must have java source code along with class files or pack java source code into jar and use.