java - Socket transferring -

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i have several classes running @ same time input server. both have sockets set up.

the problem that, though transfer same data between classes, when data arrives, not same.

here sending method:

        private boolean transferbroadcastdata() {             boolean success = false;              try {                            vector<client> clientslist =                     onlinelist.getclientslist();                  (client client : clientslist) {                         objectoutputstream objectoutputstream =                             client.getobjectoutputstream();                             objectoutputstream.writeobject(clientslist);                             objectoutputstream.flush();                 }                   success = true;              } catch (exception ioexception) {                 ioexception.printstacktrace();             }              return success;         }

and here receiving-method:

        while (true) {                 try {                     object object = objectinputstream.readobject();                      if (object instanceof vector<?>) {                         string x = "i got it:\n";                          vector<client> clients = (vector<client>) object;                          for(client c : clients) {                             x += "\n" + c;                         }                          joptionpane.showmessagedialog(clientmanager.this, x);                          userspanel.addclientstolist((vector<client>) object);                     }                      else if (object instanceof message)                         messagepanel.appendtext((message) object);                   } catch (classnotfoundexception classnotfoundexception) {                     statuspanel.updatestatus("error reading socket");                 }             }

when receive vector on clients, elements in different. not content of vector tried transfer.

what missing?

the problem use of serialization / objectoutputstream. when object serialized objectoutputstream keeps internal records "optimize" serialization process, if serialize same object twice repeats id , assumes object hasnt changed. example if run code:

objectoutputstream oos = new objectoutputstream(); myobject[] arr = new myobject[]{myobject}; oos.write(myobject); oos.write(arr);

the output might (note not actual format example):

[[myobject;id=357;foo=bar;baz=36;]] [[myobject[];id=358;data={id=357}]]

note array not serialize object again, rather id serialized version. taking 1 step further if have code:

objectoutputstream oos = new objectoutputstream(); oos.write(myobject); myobject.setbaz(99999); oos.write(myobject);

you'll end with:

[[myobject;id=357;foo=bar;baz=36;]] {id=357}

note even though object changed internal id serialized. trick when writing objects need clear internal state of objectoutputstream, can accomplished reset(). javadocs:

reset disregard state of objects written stream. state reset same new objectoutputstream.

so if take previous example , add reset:

objectoutputstream oos = new objectoutputstream(); oos.write(myobject); myobject.setbaz(99999); oos.reset(); oos.write(myobject);

you should output expected behaviour of:

[[myobject;id=357;foo=bar;baz=36;]] [[myobject;id=358;foo=bar;baz=99999;]]

one things careful of note second serialization will considered different object original serialization. depending on how transferring data , internal relationship must careful not reset stream if objects share references 1 , want relationships maintained.


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