How to detect network breakage using java program?

Question

Is there any way to detect the network breakage or weaker network, using Java?

Answer 1

you can intermittently test a http connection to a known host such as google and detect ConnectionExceptions

URLConnection con = new URL("http://www.google.com/").openConnection();
con.setUseCaches(false);
con.setAllowUserInteraction(false);

while(true)
{
    try
    {
        con.connect();
        con.getContentType(); // just to make sure the connection works
        // sleep for some interval
    }
    catch(IOException e)
    {
        // handle and break
    }
}