How can I determine the IP of my router/gateway in Java?

Question

How can I determine the IP of my router/gateway in Java? I can get my IP easily enough. I can get my internet IP using a service on a website. But how can I determine my gat

Answer 1

    try{
        String gateway;
        Process result = Runtime.getRuntime().exec("netstat -rn");

        BufferedReader output = new BufferedReader(new InputStreamReader(result.getInputStream()));

        String line = output.readLine();
        while(line != null){
            if ( line.trim().startsWith("default") == true || line.trim().startsWith("0.0.0.0") == true )
                break;      
            line = output.readLine();
        }
        if(line==null) //gateway not found;
            return;

        StringTokenizer st = new StringTokenizer( line );
        st.nextToken();
        st.nextToken();
        gateway = st.nextToken();
        System.out.println("gateway is: "+gateway);


    } catch( Exception e ) { 
        System.out.println( e.toString() );
        gateway = new String();
        adapter = new String();
    }