Wsrtjtyk

I'm trying to do a simple chat in java using a multiplex server but I'm having a little problem: I can't seem to be able to iterate through the socket channel and relay a message to all clients connected to the server.

Here's the code: https://pastebin.com/ZaXzsRpA

import java.io.*;

import java.net.*;

import java.nio.*;

import java.nio.channels.*;

import java.nio.charset.*;

import java.util.*;



public class Server

{

  static private Selector selector;

  // A pre-allocated buffer for the received data

  static private final ByteBuffer buffer = ByteBuffer.allocate( 16384 );



  // Decoder for incoming text -- assume UTF-8

  static private final Charset charset = Charset.forName("UTF8");

  static private final CharsetDecoder decoder = charset.newDecoder();





  static public void main( String args ) throws Exception {

    // Parse port from command line

    int port = Integer.parseInt( args[0] );



    try {

      // Instead of creating a ServerSocket, create a ServerSocketChannel

      ServerSocketChannel ssc = ServerSocketChannel.open();



      // Set it to non-blocking, so we can use select

      ssc.configureBlocking( false );



      // Get the Socket connected to this channel, and bind it to the

      // listening port

      ServerSocket ss = ssc.socket();

      InetSocketAddress isa = new InetSocketAddress( port );

      ss.bind( isa );



      // Create a new Selector for selecting

      selector = Selector.open();



      // Register the ServerSocketChannel, so we can listen for incoming

      // connections

      ssc.register( selector, SelectionKey.OP_ACCEPT );

      System.out.println( "Listening on port "+port );



      while (true) {

        // See if we've had any activity -- either an incoming connection,

        // or incoming data on an existing connection

        int num = selector.select();



        // If we don't have any activity, loop around and wait again

        if (num == 0) {

          continue;

        }



        // Get the keys corresponding to the activity that has been

        // detected, and process them one by one

        Set<SelectionKey> keys = selector.selectedKeys();

        Iterator<SelectionKey> it = keys.iterator();

        while (it.hasNext()) {

          // Get a key representing one of bits of I/O activity

          SelectionKey key = it.next();



          // What kind of activity is it?

          if ((key.readyOps() & SelectionKey.OP_ACCEPT) ==

            SelectionKey.OP_ACCEPT) {



            // It's an incoming connection.  Register this socket with

            // the Selector so we can listen for input on it

            Socket s = ss.accept();

            System.out.println( "Got connection from "+s );



            // Make sure to make it non-blocking, so we can use a selector

            // on it.

            SocketChannel sc = s.getChannel();

            sc.configureBlocking( false );



            // Register it with the selector, for reading

            sc.register( selector, SelectionKey.OP_READ );



          } else if ((key.readyOps() & SelectionKey.OP_READ) ==

            SelectionKey.OP_READ) {



            SocketChannel sc = null;



            try {



              // It's incoming data on a connection -- process it



              sc = (SocketChannel)key.channel();

              boolean ok = processInput( sc );



              // If the connection is dead, remove it from the selector

              // and close it

              if (!ok) {

                key.cancel();



                Socket s = null;

                try {

                  s = sc.socket();

                  System.out.println( "Closing connection to "+s );

                  s.close();

                } catch( IOException ie ) {

                  System.err.println( "Error closing socket "+s+": "+ie );

                }

              }



            } catch( IOException ie ) {



              // On exception, remove this channel from the selector

              key.cancel();



              try {

                sc.close();

              } catch( IOException ie2 ) { System.out.println( ie2 ); }



              System.out.println( "Closed "+sc );

            }

          }

        }



        // We remove the selected keys, because we've dealt with them.

        keys.clear();

      }

    } catch( IOException ie ) {

      System.err.println( ie );

    }

  }





  // Just read the message from the socket and send it to stdout

  static private boolean processInput( SocketChannel sc ) throws IOException {

        // Read the message to the buffer

        buffer.clear();

        sc.read( buffer );

        buffer.flip();



        // If no data, close the connection

        if (buffer.limit()==0) {

            return false;

        }



        // Decode and print the message to stdout

        String message = decoder.decode(buffer).toString();

        System.out.println("RECEIVED: "+ message);

        buffer.flip();

        //InetSocketAddress isa = new InetSocketAddress( port );

        //ss.bind( isa );



      // Create a new Selector for selecting

      //selector = Selector.open();



        Set<SelectionKey> keys = selector.selectedKeys();

        Iterator<SelectionKey> it = keys.iterator();

        while (it.hasNext()) {

            System.out.println("One for each connect");

            // Get a key representing one of bits of I/O activity

            SelectionKey key = it.next();

            if(key.isAcceptable())

                continue;

            SocketChannel scAux = (SocketChannel)key.channel();



            scAux.write(buffer);

            buffer.rewind();

        }



        buffer.clear();



        return true;

    }

}

Anyone able to give me some feedback?