How to use wait/nofity in socket server

Question

Dear all
that is one of sample code from a book which's use mutil connection with socket program , but i if it is possible to use wait and nofity to controle client activety by wait and notify in this sample code ?
some idea hope someone give me a help please
import java.net.*;
import java.io.*;
* Threaded Echo Server, pre-allocation scheme.
* Each Thread waits in its accept() call for a connection; this synchronizes
* on the serversocket when calling its accept() method.
* @author Ian F. Darwin.
public class EchoServerThreaded2 {
     public static final int ECHOPORT = 7;
     public static final int NUM_THREADS = 4;
     /** Main method, to start the servers. */
     public static void main(String[] av)
          new EchoServerThreaded2(ECHOPORT, NUM_THREADS);
     /** Constructor */
     public EchoServerThreaded2(int port, int numThreads)
          ServerSocket servSock;
          Socket clientSocket;
          try {
               servSock = new ServerSocket(ECHOPORT);
          } catch(IOException e) {
               /* Crash the server if IO fails. Something bad has happened */
               System.err.println("Could not create ServerSocket " + e);
               System.exit(1);
               return;     /*NOTREACHED*/
          // Create a series of threads and start them.
          for (int i=0; i<numThreads; i++) {
               new Thread(new Handler(servSock, i)).start();
     /** A Thread subclass to handle one client conversation. */
     class Handler extends Thread {
          ServerSocket servSock;
          int threadNumber;
          /** Construct a Handler. */
          Handler(ServerSocket s, int i) {
               super();
               servSock = s;
               threadNumber = i;
               setName("Thread " + threadNumber);
          public void run()
               /* Wait for a connection. Synchronized on the ServerSocket
                * while calling its accept() method. */
               while (true){
                    try {
                         System.out.println( getName() + " waiting");
                         Socket clientSocket;
                         // Wait here for the next connection.
                         synchronized(servSock) {
                              clientSocket = servSock.accept();
                         System.out.println(getName() + " starting, IP=" +
                              clientSocket.getInetAddress());
                         DataInputStream is = new DataInputStream(
                              clientSocket.getInputStream());
                         PrintStream os = new PrintStream(
                              clientSocket.getOutputStream(), true);
                         String line;
                         while ((line = is.readLine()) != null) {
                              os.print(line + "\r\n");
                              os.flush();
                         System.out.println(getName() + " ENDED ");
                         clientSocket.close();
                    } catch (IOException ex) {
                         System.out.println(getName() + ": IO Error on socket " + ex);
                         return;
}if i add end of my code like this and then the error message indicat that
java.lang.IllegalMonitorStateException: current thread not owner
try{
                    clientSocket.wait();
             }catch(InterruptedException e){
                                          clientSocket.close();
                                          clientSocket.notify();
                                        }

Answer 1

Why? Closing the socket will cause the client to return from reading the socket with a null or zero or EOFException. You don't need anything else.
In any case notifying the clientSocket will only wakeup threads in the current JVM that are waiting on it. This mechanism isn't magic, and it can't wake up another JVM.