Question

I know someone will give me a hard time for this, but here goes. I am trying to convert some C code to Java and am still learning java as I go. I am having a very difficult time figuring out how to do this conversion and learning java for that matter. Any help or pointers on where to go would be greatly appreciated.

for(d=alldevs; d; d=d->next)
    {
        printf("%d. %s", ++i, d->name);
        if (d->description)
            printf(" (%s)\n", d->description);
        else
            printf(" (No description available)\n");
    }

    if(i==0)
    {
        printf("\nNo interfaces found! Make sure WinPcap is installed.\n");
        return -1;
    }

    printf("Enter the interface number (1-%d):",i);
    scanf("%d", &inum);

    if(inum < 1 || inum > i)
    {
        printf("\nInterface number out of range.\n");
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return -1;
    }

    /* Jump to the selected adapter */
    for(d=alldevs, i=0; i< inum-1 ;d=d->next, i++);

Answer 1

A conversion offering:

public class Item {

   private String name;

   private String description;

   public Item(String name, String description) {
     this.name = name;
     this.description = description;
   }

   public String getName() {
     return this.name;
   }

   public String getDescription() {
     return this.description;
   }

}

 (defined elsewhere)
 List<Item> items;

And now the code

int index = 1;
for (Item item: items) {
   System.out.print(index + ". " + item.getName());
   if (item.getDescription() != null) {
     System.out.println(" (" + item.getDescription() + ")");
   } else {
     System.out.println"( (No Description Available)");
   }
   index++;
}    

List<NetworkInterface> nets = Collections.list(NetworkInterface.getNetworkInterfaces());
if (nets.size() == 0) {
  System.out.println();
  System.out.println("No interfaces found! Make sure WinPcap is installed.");
  return;
}

System.out.print("Enter the interface number(1-" + nets.size() + "):");
Byte[] input = new byte[100];
System.in.read(input);
String inString = new String(input);
int interfaceIndex = Integer.getInteger(inString);

if (interfaceIndex < 1 || interfaceindex > nets.size()) {
   System.out.println();
   System.out.println("Interface number out of range.");
   // freeing items is done by dereferencing
   nets = null;
   return;
} 

// jump to the selected adapter
NetworkInterface selectedInterface = nets.get(interfaceIndex);

Note that you will have to do the “real” conversion of the rest of the program; that is writing a PCap solution in Java, or writing a JNI (Java) interface to call the PCap library routines.