Checking for valid (and working) address

Question

(sorry if i posted in the wrong forum... i didn't found any that suits better my problem)
that's the question: i have a string and need to check if it's a valid host name/ip address and also check if it's up and running at the moment. to solve the host name, i have the following code:
try {
URL url = new URL(sURL);
HttpURLConnection uc = (HttpURLConnection) url.openConnection() ;
uc.setRequestMethod("GET") ;
uc.connect();
uc.getResponseMessage();
catch (IOException ioe) {
//wrong url/not working
but it doesn't work with ip addresses. Someone suggested me to use InetAddress.isReachable(int), but it's only avaliable since Java 1.5, and i must use 1.4. Another way around would be to use InetAddress.get(Canonical)HostName(), but it may fail even with a valid ip address, and i can't allow that.
can someone give me a hand?
thanks!

Answer 1

(sorry if i posted in the wrong forum... i didn't
found any that suits better my problem)
that's the question: i have a string and need to
check if it's a valid host name/ip address and also
check if it's up and running at the moment. to solve
the host name, i have the following code:Easy - it isn't possible at all.
If and only if you were to use ICMP (which you can't in 1.4 using just java) and if and only if the target computer responded to ICMP then you could use that.
That is seldom very useful because generally one doesn't care if a computer responds to ICMP. What they need to know is if the computer is actually doing what it is supposed.
For example if you have an http server, what you care about is if it is actually handling http requests. (The computer can be up and not handling http requests.)
Not to mention of course that a host name requires that the DNS server respond to it first. And just because the DNS server is failing it doesn't mean that the target PC is failiing.
But if you really want to do nothing but ICMP then you can use Runtime.exec() and an OS specific command (usually 'ping') to do just that.