One of the most useful pieces of information you can get from a network interface is the list of IP addresses that are assigned to it. You can obtain this information from aNetworkInterface
instance by using one of two methods. The first method,getInetAddresses()
, returns anEnumeration
ofInetAddress
. The other method,getInterfaceAddresses()
, returns a list ofjava.net.InterfaceAddress
instances. This method is used when you need more information about an interface address beyond its IP address. For example, you might need additional information about the subnet mask and broadcast address when the address is an IPv4 address, and a network prefix length in the case of an IPv6 address.The following example program lists all the network interfaces and their addresses on a machine:
The following is sample output from the example program:import java.io.*; import java.net.*; import java.util.*; import static java.lang.System.out; public class ListNets { public static void main(String args[]) throws SocketException { Enumeration<NetworkInterface> nets = NetworkInterface.getNetworkInterfaces(); for (NetworkInterface netint : Collections.list(nets)) displayInterfaceInformation(netint); } static void displayInterfaceInformation(NetworkInterface netint) throws SocketException { out.printf("Display name: %s\n", netint.getDisplayName()); out.printf("Name: %s\n", netint.getName()); Enumeration<InetAddress> inetAddresses = netint.getInetAddresses(); for (InetAddress inetAddress : Collections.list(inetAddresses)) { out.printf("InetAddress: %s\n", inetAddress); } out.printf("\n"); } }Display name: bge0 Name: bge0 InetAddress: /fe80:0:0:0:203:baff:fef2:e99d%2 InetAddress: /121.153.225.59 Display name: lo0 Name: lo0 InetAddress: /0:0:0:0:0:0:0:1%1 InetAddress: /127.0.0.1