Multiple threads but they are using the same thread ID

Question

I'm a newbie in Java programming. I have the following codes, please take a look and tell me what wrong with my codes: server side written in Java, client side written in C. Please help me out, thanks for your time.
Here is my problem: why my server program assigns the same thread ID for both threads???
.Server side: start server program
.Client side: set auto startup in /etc/rc.local file in a different machine, so whenever this machine boots up, the client program will start automatically.
==> here is the result with 2 clients, why they always come up the same thread ID ????????
Waiting for client ...
Server thread 1024 running
Waiting for client ...
Server thread 1024 running
But if I do like this, they all work fine:
.Server side: start server program
.Client side: telnet or ssh to each machine, start the client program
==> here is the result:
Waiting for client ...
Server thread 1024 running
Waiting for client ...
Server thread 1025 running
server.java file:
import java.io.*;
import java.net.*;
import java.awt.*;
import java.util.Hashtable;
import java.util.Enumeration;
import java.util.regex.Pattern;
import java.util.Date;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class Server extends Frame implements Runnable
private ServerThread clients[] = new ServerThread[50];
private ServerSocket server = null;
private Thread thread = null;
private int clientCount = 0;
//some variables over here
public Server(int port)
//GUI stuffs here
//network stuff
try
System.out.println("Binding to port " + port + ", please wait ...");
server = new ServerSocket(port);
System.out.println("Server started: " + server);
start();
catch(IOException ioe)
System.out.println("Can not bind to port " + port + ": " + ioe.getMessage());
public boolean action(Event e, Object arg)
//do something
return true;
public synchronized void handle(int ID, String input)
//do something
public synchronized void remove(int ID)
int pos = findClient(ID);
if (pos >= 0)
//remove a client
ServerThread toTerminate = clients[pos];
System.out.println("Removing client thread " + ID + " at " + pos);
if (pos < clientCount-1)
for (int i = pos+1; i < clientCount; i++)
clients[i-1] = clients;
clientCount--;
try
{  toTerminate.close(); }
catch(IOException ioe)
{  System.out.println("Error closing thread: " + ioe); }
toTerminate.stop();
private void addThread(Socket socket)
if (clientCount < clients.length)
clients[clientCount] = new ServerThread(this, socket);
try
clients[clientCount].open();
clients[clientCount].start();
clientCount++;
catch(IOException ioe)
System.out.println("Error opening thread: " + ioe);
else
System.out.println("Client refused: maximum " + clients.length + " reached.");
public void run()
while (thread != null)
try
{       System.out.println("Waiting for a client ...");
addThread(server.accept());
catch(IOException ioe)
System.out.println("Server accept error: " + ioe); stop();
public void start()
if(thread == null)
thread = new Thread(this);
thread.start();
public void stop()
if(thread != null)
thread.stop();
thread = null;
private int findClient(int ID)
for (int i = 0; i < clientCount; i++)
if (clients[i].getID() == ID)
return i;
return -1;
public static void main(String args[])
Frame server = new Server(1500);
server.setSize(650,400);
server.setLocation(100,100);
server.setVisible(true);
ServerThread.java file
import java.net.*;
import java.io.*;
import java.lang.*;
public class ServerThread extends Thread
private Server server = null;
private Socket socket = null;
private int ID = -1;
InputStreamReader objInStreamReader = null;
BufferedReader objInBuffer = null;
PrintWriter objOutStream = null;
public ServerThread(Server server, Socket socket)
super();
server = _server;
socket = _socket;
ID = socket.getPort();
public void send(String msg)
objOutStream.write(msg);
objOutStream.flush();
public int getID()
return ID;
public void run()
System.out.println("Server thread " + ID + " running");
while(true)
try{
server.handle(ID,objInBuffer.readLine());
catch(IOException ioe)
System.out.println(ID + "Error reading: " + ioe.getMessage());
//remove a thread ID
server.remove(ID);
stop();
public void open() throws IOException
//---Set up streams---
objInStreamReader = new InputStreamReader(socket.getInputStream());
objInBuffer = new BufferedReader(objInStreamReader);
objOutStream = new PrintWriter(socket.getOutputStream(), true);
public void close() throws IOException
if(socket != null) socket.close();
if(objInStreamReader != null) objInStreamReader.close();
if(objOutStream !=null) objOutStream.close();
if(objInBuffer !=null) objInBuffer.close();
And client.c file
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h> /* close */
#include <time.h>
#define SERVER_PORT 1500
#define MAX_MSG 100
//global variables
long lines = 0;
int sd = 0;
char command[100];
time_t t1,t2;
double timetest = 0.00;
int main (int argc, char *argv[])
int rc, i = 0, j = 0;
struct sockaddr_in localAddr, servAddr;
struct hostent *h;
char buf[100];
FILE *fp;
h = gethostbyname(argv[1]);
if(h==NULL) {
printf("unknown host '%s'\n",argv[1]);
exit(1);
servAddr.sin_family = h->h_addrtype;
memcpy((char *) &servAddr.sin_addr.s_addr, h->h_addr_list[0], h->h_length);
servAddr.sin_port = htons(SERVER_PORT);
/* create socket */
sd = socket(AF_INET, SOCK_STREAM, 0);
if(sd<0) {
perror("cannot open socket ");
exit(1);
/* bind any port number */
localAddr.sin_family = AF_INET;
localAddr.sin_addr.s_addr = htonl(INADDR_ANY);
localAddr.sin_port = htons(0);
rc = bind(sd, (struct sockaddr *) &localAddr, sizeof(localAddr));
if(rc<0) {
printf("%s: cannot bind port TCP %u\n",argv[1],SERVER_PORT);
perror("error ");
exit(1);
/* connect to server */
rc = connect(sd, (struct sockaddr *) &servAddr, sizeof(servAddr));
if(rc<0) {
perror("cannot connect ");
exit(1);
//send register message
rc = send(sd, "register\n", strlen("register\n"), 0);
//if can't send
if(rc < 0)
close(sd);
exit(1);
//wait here until get the flag from server
while(1)
buf[0] = '\0';
rc = recv(sd,buf,MAX_MSG-1,0);
if(rc < 0)
perror("receive error\n");
close(sd);
exit(1);
buf[rc] = '\0';
if(strcmp(buf,"autoplay")==0)
//do something here
else if(strcmp(buf,"exit")==0)
printf("exiting now ....\n");
close(sd);
exit(1);
return 0;

Answer 1

Yes......I do so all the time.