Getting a List of computers on a network

Question

I have been trying to get the name or the ip of all computers on the network I am on in Java.

I have tried pinging for each one with 2 different ways:

Process p = java.lang.Runtime.getRuntime().exec("ping -n 1 " + host);
returnval = p.waitFor();

This returns 0 for every address even when it fails.

and

InetAddress.getByAddress(host).isReachable(timeout);

Always returning false

The computers appear in Windows network tab in explorer.

Is there some way to retrieve a list of names of those computer in Java to use?

This is not a Java question. You know how to run external native programs, so your question is purely a Windows/Linux/MAC question. — Xabster, Aug 18 '14 at 02:49
have you tried [google your question](https://www.google.com/#q=java+get+a+list+of+computers+on+a+network)? — Baby, Aug 18 '14 at 02:51
Are you reading the response from the process. What does *"However both do not work"* actually mean? Did they throw and exception, fail to run not report anything?? — MadProgrammer, Aug 18 '14 at 02:54
@Funkydiddykong then it's customary to accept an answer. That shows people you don't need more help/comments/answers. — Xabster, Aug 18 '14 at 03:52

score 3 · Accepted Answer · answered Aug 18 '14 at 02:52

3

Windows?

net view

or

arp -a

Last one gives MAC addresses.

answered Aug 18 '14 at 02:52

Xabster

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Funkydiddykong · Answer 2 · 2014-08-18T06:58:32.050

Extending on Xabsters answer I was able to achieve a list via the following code.

Runtime rt = Runtime.getRuntime();
    try {
        Process p = rt.exec("arp -a");

        BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));

        String s = null;
        while ((s = stdInput.readLine()) != null) {
            s = s.trim();
            if (!s.startsWith("I") && s.length >0)
            System.out.println(s.split(" ")[0]);
        }

    } catch (Exception e) {
        e.printStackTrace();
    }

score 1 · Answer 3 · answered Aug 18 '14 at 06:37

1

Just a complement to above answers.

InetAddress.getByName(host).isReachable(timeout); which would be the java way of doing this (portable across different architectures), did not work because it expects a host name. When using IP addresses, you should use :

InetAddress.getByAddress(host).isReachable(timeout);

That is the platform independant way.

answered Aug 18 '14 at 06:37

Serge Ballesta

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Sorry, that was a mistake in the question. – Funkydiddykong Aug 18 '14 at 06:39

Getting a List of computers on a network

3 Answers3