找不到类？？？

package javaworks.net.multicast;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
public class MChatServer
{
public static final String GROUP_IP="230.0.0.1";
public static final int MAX_PACKET_SIZE=65507;
public static final int SERVER_PORT=2008;
public static void main(String args[])throws IOException
{
System.out.println("==========UDP cast=========");
try
{
MulticastSocket server= new MulticastSocket(SERVER_PORT);
InetAddress group= new InetAddress.getByName(GROUP_IP); server.joinGroup(group);
System.out.println("now listenning"+server.getLocalPort()+"...");
while(true)
{
try
{

byte buffer[]=new byte[MAX_PACKET_SIZE];
DatagramPacket packet=new DatagramPacket(buffer,buffer.length);
server.receive(packet);
String s=new String(packet.getData(),0,packet.getLength());
System.out.println(""+packet.getAddress().getHostAddress()+":"+packet.getPort()+":"+s);
if("shutdown".equals(s))
break;
}
catch(Exception e)
{
e.printStackTrace();
}
}
server.leaveGroup(group);
server.close();

}
catch(Exception e)
{
e.printStackTrace();
}
}
}

运行结果：
cannot find symbol class getByname
怎么回事？这还是书上的例子。。。。