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POjava client server serialization problem
 

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  1. POjava client server serialization problem
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    <p>hi i am working on a client server programme with containing some special functions like sending private message, show online list etc. so i know i must use serialization and first i managed it but after a while a screwed up :) nowadays i spending time for learn to serialize. i will share only meaningfull parts for prevent comlpexity. and i wanna learn where i making wrong. so thanks for your help anyway. here is a part of server code;</p> <pre><code> public class Server { private ServerSocket ss; private Socket socket; private Map&lt;Socket,DataOutputStream&gt; list = new HashMap&lt;Socket,DataOutputStream&gt;(); private LinkedList&lt;Person&gt; client_list = new LinkedList&lt;Person&gt;(); private String socketName; private Object lockObj = new Object(); public Server(int port_number) throws IOException{ create_Server(port_number); } public static void main(String[] args) throws IOException { int port_number=23; new Server(port_number); } private void create_Server(int port_number) throws IOException{ ss = new ServerSocket(port_number); System.out.println("Server is ready!"); while(true){ socket=ss.accept(); System.out.println(socket.getLocalAddress().getHostName() + " was connected!"); send_con_mes(); list.put(socket,new DataOutputStream(socket.getOutputStream()) ); ServerThread st = new ServerThread(socket,this); Person per = new Person(socket.getInetAddress().toString()); client_list.add(per); st.start(); } } public LinkedList&lt;Person&gt; send_list(){ return client_list; } </code></pre> <p>so i am creating the server and waiting for response for any socket. moreover i used list for save the socket and its output and clien_list saves Object person (person is a serializable object ).</p> <p>here is serverthread part</p> <pre><code>public class ServerThread extends Thread { private Socket s; private Server srv; private String socketName; private StringTokenizer str; private String message = ""; private LinkedList&lt;Person&gt; client_list; private ObjectOutputStream oos; private static int i=0; public ServerThread(Socket s,Server srv){ this.s = s; this.srv = srv; try { oos = new ObjectOutputStream(s.getOutputStream()); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public void setList(){ client_list = srv.send_list(); } private LinkedList&lt;Person&gt; getList(){ return client_list; } @Override public void run() { String msg; String token; DataInputStream dis; try { dis = new DataInputStream(s.getInputStream()); while(true){ msg = dis.readUTF(); srv.send_to_All(msg, s); setList(); oos.writeObject(getList()); oos.flush(); } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally{ try { srv.remove_Connection(s); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } </code></pre> <p>so i send client_list over on a <code>ObjectOutputStream oos</code> to clients.</p> <p>finally here is client part which takes the list and deserialize person object and read the information...</p> <pre><code>public class Client extends javax.swing.JFrame implements Runnable { private DataOutputStream dos; private DataInputStream dis; private Socket s; private String Client_name; private String Ip_addr; private Font font = new Font("Arial", Font.PLAIN, 13); private int click_num_b=0; private int click_num_i=0; private LinkedList&lt;Person&gt; client_list; private FileOutputStream fos; private PrintStream pts; private ObjectInputStream socketIn; /** Creates new form Client */ public Client() { initComponents(); Screen.setEditable(false); Text_Field.setFont(font); Screen.setFont(font); start_Chat(); } @Override public void run() { try { while(true){ read_list(); String message = dis.readUTF(); Screen.append(message + "\n"); } } catch (IOException ex) { Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex); } } private void read_list() throws IOException{ socketIn = new ObjectInputStream(s.getInputStream()); try { client_list = (LinkedList&lt;Person&gt;) socketIn.readObject(); for (Iterator&lt;Person&gt; itr = client_list.iterator(); itr.hasNext();) { Person per = itr.next(); pts.println(per.getnickName() ); } socketIn.close(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public void start_Chat() { try { Ip_addr = JOptionPane.showInputDialog("Enter the IP number of the server to connect : "); s = new Socket(Ip_addr, 23); Client_name = JOptionPane.showInputDialog("Enter your Nickname : "); dis = new DataInputStream(s.getInputStream()); dos = new DataOutputStream(s.getOutputStream()); fos = new FileOutputStream("personList.txt"); pts = new PrintStream(fos); new Thread(Client.this).start(); </code></pre> <p>in here private <code>ObjectInputStream socketIn;</code> takes the serializable object and writes on a file. here is some errors which i am facing with</p> <pre><code>java.io.EOFException at java.io.DataInputStream.readUnsignedShort(Unknown Source) at java.io.DataInputStream.readUTF(Unknown Source) at java.io.DataInputStream.readUTF(Unknown Source) at ServerThread.run(ServerThread.java:58) SEVERE: null java.io.StreamCorruptedException: invalid type code: 00 at java.io.ObjectInputStream.readObject0(Unknown Source) at java.io.ObjectInputStream.readObject(Unknown Source) at Client.read_list(Client.java:81) at Client.run(Client.java:61) at java.lang.Thread.run(Unknown Source) </code></pre> <p>so i appreciated if you can help me to handles this issue. </p>
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    1. USquartaela
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      1. VTUpMod
    1. COIt's a bit ugly to declare `socket` as a class variable and only use it as a variable local to a method.
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      1. UScorsiKa
    2. COwell i will be glad if you can explain more clearly your idea :)
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      1. USquartaela
    3. COSure. I would move `Socket socket` into the `while` loop in `create_Server`. This will prevent anything from ever messing with the socket object and more assuredly protect it. You never want to expose information unnecessarily.
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