Very Simple Regex Question

Like this:

String baseUrl;
Pattern p = Pattern.compile("^(([a-zA-Z]+://)?[a-zA-Z0-9.-]+\\.[a-zA-Z]+(:\d+)?/");
Matcher m = p.matcher(str); 
if (m.matches())
    baseUrl = m.group(1);

However, you should use the URI class instead, like this:

URI uri = new URI(str);

A one liner without regexp:

String baseUrl = url.substring(0, url.indexOf('/', url.indexOf("//")+2));