Appreciation about Pcap devices

Question

I'm just trying to get automatically the active device on my System.

For Example:

My PC has two devices. 1. TAP-Windows Adapter V9 2. Intel(R) Ethernet Connection

Actually the active device is the Intel Connection.

So I want that my application can automatically use the active device to dump a pcap.

My Idea is to search for the Subnetmask in both devices. The active device has an INET4 IP like this mask=[INET4: 255.255.255.0]. The deactive one gives me this: mask=[0]

Is it the right thinking, that an active device never gets a mask of 0?

This extends also for the broadcast.

Here is my implementation:

static public PcapIf selectActiveDev(List alldevs){ PcapIf device = new PcapIf();

for(int a = 0; a<=alldevs.size()-1; a++){
    if(alldevs.get(a).getAddresses().get(0).getNetmask().toString() != "0"){
        device = alldevs.get(a);        
    }
}
return device;  

}

I'm using JNetPcap 1.3.0 with eclipse. :)