Hello,
First I'd like to say I am really pleased with your course layout thus
far. I seem to be having a problem compiling your sample multicast
networking program on my mac.
The exception/compiler output is as follows:
run:
MulticastSocket is created at port 5000
Exception in thread "main" java.net.SocketException: Can't assign requested
address
at java.net.PlainDatagramSocketImpl.join(Native Method)
at
java.net.AbstractPlainDatagramSocketImpl.join(AbstractPlainDatagramSocketImpl.java:179)
at java.net.MulticastSocket.joinGroup(MulticastSocket.java:323)
at MulticastChatServer.main(MulticastChatServer.java:27)
/Users/Benjamin/Library/Caches/NetBeans/8.1/executor-snippets/run.xml:53:
Java returned: 1
BUILD FAILED (total time: 0 seconds)
The code is:
import java.net.*;
public class MulticastChatServer {
public static void main(String args[])
throws Exception {
// Default port number we are going to use
int portnumber = 5000;
if (args.length >= 1) {
portnumber = Integer.parseInt(args[0]);
}
// Create a MulticastSocket
MulticastSocket serverMulticastSocket =
new MulticastSocket(portnumber);
System.out.println("MulticastSocket is created at port " +
portnumber);
// Determine the IP address of a host, given the host name
// The host name can either be a machine name, such as "java.sun.com
",
// or a textual representation of its IP address. If a literal IP
// address is supplied, only the validity of the address format is
checked.
InetAddress group = InetAddress.getByName("225.4.5.6");
// getByName- returns IP address of given host
serverMulticastSocket.joinGroup(group);
System.out.println("joinGroup method is called...");
boolean infinite = true;
// Continually receives data and prints them
while (infinite) {
byte buf[] = new byte[1024];
DatagramPacket data =
new DatagramPacket(buf, buf.length);
serverMulticastSocket.receive(data);
String msg =
new String(data.getData()).trim();
System.out.println("Message received from client = " + msg);
}
serverMulticastSocket.close();
}
}
My network interface configuration is as follows:
Last login: Wed Sep 28 18:26:58 on ttys000
Benjamins-MacBook-Pro:~ Benjamin$ ifconfig
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
options=3<RXCSUM,TXCSUM>
inet6 ::1 prefixlen 128
inet 127.0.0.1 netmask 0xff000000
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
nd6 options=1<PERFORMNUD>
gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280
stf0: flags=0<> mtu 1280
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether a4:5e:60:d9:ad:21
inet6 fe80::a65e:60ff:fed9:ad21%en0 prefixlen 64 scopeid 0x4
inet 192.168.1.10 netmask 0xffffff00 broadcast 192.168.1.255
nd6 options=1<PERFORMNUD>
media: autoselect
status: active
en1: flags=963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX> mtu 1500
options=60<TSO4,TSO6>
ether 4a:00:01:1f:c8:30
media: autoselect <full-duplex>
status: inactive
en2: flags=963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX> mtu 1500
options=60<TSO4,TSO6>
ether 4a:00:01:1f:c8:31
media: autoselect <full-duplex>
status: inactive
p2p0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 2304
ether 06:5e:60:d9:ad:21
media: autoselect
status: inactive
awdl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1484
ether de:39:ac:c0:e3:7c
inet6 fe80::dc39:acff:fec0:e37c%awdl0 prefixlen 64 scopeid 0x8
nd6 options=1<PERFORMNUD>
media: autoselect
status: active
bridge0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=63<RXCSUM,TXCSUM,TSO4,TSO6>
ether a6:5e:60:9d:fb:00
Configuration:
id 0:0:0:0:0:0 priority 0 hellotime 0 fwddelay 0
maxage 0 holdcnt 0 proto stp maxaddr 100 timeout 1200
root id 0:0:0:0:0:0 priority 0 ifcost 0 port 0
ipfilter disabled flags 0x2
member: en1 flags=3<LEARNING,DISCOVER>
ifmaxaddr 0 port 5 priority 0 path cost 0
member: en2 flags=3<LEARNING,DISCOVER>
ifmaxaddr 0 port 6 priority 0 path cost 0
nd6 options=1<PERFORMNUD>
media: <unknown type>
status: inactive
utun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
inet6 fe80::935a:dea6:fc62:3b81%utun0 prefixlen 64 scopeid 0xa
nd6 options=1<PERFORMNUD>
Benjamins-MacBook-Pro:~ Benjamin$ -Djava.net.preferIPv4Stack=true
-bash: -Djava.net.preferIPv4Stack=true: command not found
Benjamins-MacBook-Pro:~ Benjamin$
My basic computer info is in attachment:
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