LOG4J in serialized Thread

Question

Hi,
I've made a class ClientServer which extends Thread implements Remote, Serializable.
Inside, i've got this attribute : private transient static Logger LOG = Logger.getLogger(ClientServer.class);I've made another class ClientPartenaire which extends UnicastRemoteObject implements Remote
Inside, i've got this attribute : private transient static Logger LOG = Logger.getLogger(ClientPartenaire.class);Then, I've generated stubs for both classes.
Thus, I try to serialize it while using RMI server.
When I do
Naming.rebind("server", new ClientPartenaire ())everything works well
but when I do
Naming.rebind("server", new ClientServer("demeter"));I get this stacktrace : java.rmi.ServerError: Error occurred in server thread; nested exception is:
     java.lang.NoClassDefFoundError: Lorg/apache/log4j/Logger;
     at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:382)
     at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:240)
     at sun.rmi.transport.Transport$1.run(Transport.java:153)
     at java.security.AccessController.doPrivileged(Native Method)
     at sun.rmi.transport.Transport.serviceCall(Transport.java:149)
     at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:460)
     at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:701)
     at java.lang.Thread.run(Thread.java:595)
     at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Unknown Source)
     at sun.rmi.transport.StreamRemoteCall.executeCall(Unknown Source)
     at sun.rmi.server.UnicastRef.invoke(Unknown Source)
     at sun.rmi.registry.RegistryImpl_Stub.bind(Unknown Source)
     at java.rmi.Naming.bind(Unknown Source)
     at i2.application.demeter.client.RunClient.main(RunClient.java:61)
Caused by: java.lang.NoClassDefFoundError: Lorg/apache/log4j/Logger;
     at java.lang.Class.getDeclaredFields0(Native Method)
     at java.lang.Class.privateGetDeclaredFields(Class.java:2232)
     at java.lang.Class.getDeclaredField(Class.java:1852)
     at java.io.ObjectStreamClass.getDeclaredSUID(ObjectStreamClass.java:1555)
     at java.io.ObjectStreamClass.access$600(ObjectStreamClass.java:47)
     at java.io.ObjectStreamClass$2.run(ObjectStreamClass.java:381)
     at java.security.AccessController.doPrivileged(Native Method)
     at java.io.ObjectStreamClass.<init>(ObjectStreamClass.java:373)
     at java.io.ObjectStreamClass.lookup(ObjectStreamClass.java:268)
     at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:504)If I comment all lines using attribute LOG and delete attribute LOG, keeping the import for Logger class, I get this error again. Then, if I delete the import, the error disapears !
Any idea why do I get this error ?
Thanks a lot for your help :)

Answer 1

Thanks for your kind words. On second thoughts, I do
have a doubt regarding threads. In the above program
[or for that matter any program using Threads], is
there some way I can ensure that all the threads
start at the same time? No. All threads can't start at the same time.
My concern is more towards
the fact that I want execution of the next step [in
this case, the System.out.println saying "hello"] to
continue only after all threads have been executed.
I feel that in the approach I have used, there are
chances of a thread finishing before I reach the
join() portion of the code.Does it matter if the thread has finished before you call join? It only means that join will return immediately.
Kaj