networking - Java HTTP getResponseCode returns 200 for non-existent URL

Question

I was expecting this code to return a 404, however it produces the output :

"Response code is 200"

Would it be possible to learn how to differentiate between existent and non-existent web pages . . . thanks so much,

    try
    {
    // create the HttpURLConnection
    URL url = new URL("http://www.thisurldoesnotexist");
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();

    System.out.println("Response code is " + connection.getResponseCode());
    }

Answer 1

EDIT: I see you've call openConnection() but not connect() - could that be the problem? I would expect getResponseCode() to actually make the request if it hasn't already, but it's worth just trying that...

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That suggests you've possible got some DNS resolver which redirects to a "helper" (spam) page, or something like that.

The easiest way to see exactly what's going on here is to use Wireshark - have that up and capturing traffic (HTTP-only, to make life easier) and then run your code. You should be able to see what's going on that way.

Note that I wouldn't have expected a 404 - because that would involve being able to find a web server to talk to to start with. If you're trying to go to a host which doesn't involve, there shouldn't be an HTTP response at all. I'd expect connect() to throw an exception.