s.accept ( ) method, gives me an error ?

[Ayman Jaffar]

Hi all,
I've a win98 OS and I don't recal installing any S/W for server.
I've got this program from a book and I want to know why it's not working.
I'm getting this message exactly:
C:\Delete>javac SimpleServer.java
SimpleServer.java:20: variable s might not have been initialized
Socket s1 = s.accept();
^
1 error

and here is my program:
public class SimpleServer {
public static void main(String args[]) {
ServerSocket s;
// Register service to port 5432 or anyother number
try {
s = new ServerSocket(5432);
} catch (IOException e) { }

while (true) {
try {
// Wait here and listen for a connection
Socket s1 = s.accept();
// Get output stream associated with the socket
OutputStream s1out = s1.getOutputStream();
DataOutputStream dos = new DataOutputStream(s1out);
// Send your string!
dos.writeUTF("Hello Net World!");
// Close the connection, but not the server socket
dos.close();
s1.close();
} catch (IOException e) { }
} //end of while
}//end of main
}//end of class
Thanks alot

[Carl Trusiak]

Which Version of the JDK are you using? The problem appears to be a condition called something like self referential error. It's a documented bug with certain versions. Basically the compiler sees that s may not get itialized in the constructor because it exists inside of braces and it complains. set s to null when you declare it
ServerSocket s = null;
or in the catch statement of the constructor prevents this.
One note, never have an empty catch block, this will mask errors and can be a horror to debug. a simple e.printStackTrace() will save a lot of hair!

import java.io.*;
import java.net.*;
public class SimpleServer
{
    public static void main(String args[]) 
    {
        ServerSocket s;
        // Register service to port 5432 or anyother number
        try 
        {
            s = new ServerSocket(5432);
        } 
        catch (IOException e) 
        {
            s = null; 
            e.printStackTrace();
        }

        while (true) 
        {
            try 
            {
                 // Wait here and listen for a connection
                 Socket s1 = s.accept();
                 // Get output stream associated with the socket
                 OutputStream s1out = s1.getOutputStream();
                 DataOutputStream dos = new DataOutputStream(s1out);
                 // Send your string!
                 dos.writeUTF("Hello Net World!");
                 // Close the connection, but not the server socket
                 dos.close();
                 s1.close();
            } 
            catch (IOException e) 
            { 
                e.printStackTrace();
            }
        } //end of while
    }//end of main
}//end of class

Hope This Helps

[Ayman Jaffar]

Thank you Carl Trusiak my program "SimpleServer.java" is now working becuase I set "ServerSocket s = null;"....exactly as you said !!
I've jdk 1.3 and I guess it is a bug.
I've just finished runnig both "SimpleClient.java" and "SimpleServer.java" and they're both workin' fine.
Thanks again.

[This message has been edited by Ayman Jaffar (edited January 09, 2001).]