Network Interface Parameters
You can access network parameters about a network interface beyond the name and IP addresses assigned to it
You can discover if a network interface is "up" (that is, running) with the isUP() method. The following methods indicate the network interface type:
isLoopback()indicates if the network interface is a loopback interface.isPointToPoint()indicates if the interface is a point-to-point interface.isVirtual()indicates if the interface is a virtual interface.
The supportsMulticast() method indicates whether the network interface supports multicasting. The getHardwareAddress() method returns the network interface's physical hardware address, usually called MAC address, when it is available. The getMTU() method returns the Maximum Transmission Unit (MTU), which is the largest packet size.
The following example expands on the example in Listing Network Interface Addresses by adding the additional network parameters described on this page:
import java.io.*;
import java.net.*;
import java.util.*;
import static java.lang.System.out;
public class ListNetsEx {
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("Up? %s\n", netint.isUp());
out.printf("Loopback? %s\n", netint.isLoopback());
out.printf("PointToPoint? %s\n", netint.isPointToPoint());
out.printf("Supports multicast? %s\n", netint.supportsMulticast());
out.printf("Virtual? %s\n", netint.isVirtual());
out.printf("Hardware address: %s\n",
Arrays.toString(netint.getHardwareAddress()));
out.printf("MTU: %s\n", netint.getMTU());
out.printf("\n");
}
}
The following is sample output from the example program:
Display name: bge0 Name: bge0 InetAddress: /fe80:0:0:0:203:baff:fef2:e99d%2 InetAddress: /129.156.225.59 Up? true Loopback? false PointToPoint? false Supports multicast? false Virtual? false Hardware address: [0, 3, 4, 5, 6, 7] MTU: 1500 Display name: lo0 Name: lo0 InetAddress: /0:0:0:0:0:0:0:1%1 InetAddress: /127.0.0.1 Up? true Loopback? true PointToPoint? false Supports multicast? false Virtual? false Hardware address: null MTU: 8232