Java IP of subnet

Hi all, I have a problem :

I was writing a little program that display all ip (all host) connected to my router and so in my same subnetwork.

Now I'll show my idea:

Code :

---

 private boolean pingHost(InetAddress ip) throws IOException{
 
		 if(ip.isReachable(1000)){
			 System.out.println(ip.toString() +"IS REACHABLE");
			 return true;
		 }
		 else{
			 return false;
		 }

---

I have made this to generate all ip in my range:

Code :

---

private ArrayList<InetAddress> generateAllSubnetIP(InetAddress localHostIP){
		  ArrayList<InetAddress> allsubnetIP = new ArrayList<InetAddress>();
		  byte[] localIPbyte = localHostIP.getAddress();
		  for (int i = 0; i < 256; i++) {
 
				  byte[] tempIP={localIPbyte[0],localIPbyte[1],localIPbyte[2],(byte)i};
				try {
					allsubnetIP.add(InetAddress.getByAddress(tempIP));
				} catch (UnknownHostException e) {
					System.out.println("UnknownHost generating all ip address");
					e.printStackTrace();
				}
			  }
		  return allsubnetIP;
	   }

---

and then I call pingHost for all the ip stored in the ArrayList.

but this doesn't work...


Any idea ?

I hope that you can understand my question...if not ask me for more details...

Thank you...