Question

I am making a Client Server application for my Android phone.

I have created a UDP Server in Python which sits and listens for connections.

I can put either the server IP address in directly like 192.169.0.100 and it sends data fine. I can also put in 192.168.0.255 and it find the server on 192.169.0.100.

Is it possible to get the broadcast address of the network my Android phone is connected to? I am only ever going to use this application on my Wifi network or other Wifi networks.

Cheers

Answer 1

As the broadcast IP address is the current IP address but finishing with 255, you can do something like this:

public String getLocalIpAddress() {
    try {
        for (Enumeration<NetworkInterface> en = NetworkInterface
                .getNetworkInterfaces(); en.hasMoreElements();) {
            NetworkInterface intf = en.nextElement();
            for (Enumeration<InetAddress> enumIpAddr = intf.getInetAddresses(); enumIpAddr.hasMoreElements();) {
                InetAddress inetAddress = enumIpAddr.nextElement();
                if (!inetAddress.isLoopbackAddress()) {
                    return inetAddress.getHostAddress().toString();
                }
            }
        }
    } catch (SocketException ex) {}
    return null;
}

public static String getBroadcast() throws SocketException {
    System.setProperty("java.net.preferIPv4Stack", "true");
    for (Enumeration<NetworkInterface> niEnum = NetworkInterface.getNetworkInterfaces(); niEnum.hasMoreElements();) {
        NetworkInterface ni = niEnum.nextElement();
        if (!ni.isLoopback()) {
            for (InterfaceAddress interfaceAddress : ni.getInterfaceAddresses()) {
                return interfaceAddress.getBroadcast().toString().substring(1);
            }
        }
    }
    return null;
}