How do I disable the Internet connection in Android Emulator?

I am trying to check Internet connectivity on Android using the following method. I have a Wi-Fi connection.

private boolean checkInternetConnection() {
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

    // Test for connection
    if (cm.getActiveNetworkInfo() != null
            && cm.getActiveNetworkInfo().isAvailable()
            && cm.getActiveNetworkInfo().isConnected()) {
        return true;
    }
    else {
        // No conection
        return false;
    }
}

I disconnect my PC from the Internet and then try to run the above method. Still it always returns true!? Why?