Java Quickly check for network connection

Question

My issue is fairly straightforward. My program requires immediate notification if a network connection is lost. I\'m using Java 5, so I\'m unable to use the very handy feature

Answer 1

From JGuru

Starting with Java 5, there is an isReachable() method in the InetAddress class. You can specify either a timeout or the NetworkInterface to use. For more information on the underlying Internet Control Message Protocol (ICMP) used by ping, see RFC 792 (http://www.faqs.org/rfcs/rfc792.html).

Usage from Java2s

  int timeout = 2000;
  InetAddress[] addresses = InetAddress.getAllByName("www.google.com");
  for (InetAddress address : addresses) {
    if (address.isReachable(timeout))
      System.out.printf("%s is reachable%n", address);
    else
      System.out.printf("%s could not be contacted%n", address);
  }

If you want to avoid blocking use Java NIO (Non-blocking IO) in the java.nio package

String host = ...; 
InetSocketAddress socketAddress = new InetSocketAddress(host, 80); 
channel = SocketChannel.open(); 
channel.configureBlocking(false); 
channel.connect(socketAddress);