Extract host name/domain name from URL string

Question

I have a URL like http://hostname:port_no/control/login.jsp.

I have the above url stored in some String.Now, I need to extract hostname from the String.

I am doing like this in my Java code

String domain = url.substring(url.indexOf('/') + 2, url.lastIndexOf(':'));

I want to know if there is any better way to do the same.

Answer 1

You can use the java.net.URI-class to extract the hostname from the string.

Here below is a method from which you can extract your hostname from a string.

public String getHostName(String url) {
    URI uri = new URI(url);
    String hostname = uri.getHost();
    // to provide faultproof result, check if not null then return only hostname, without www.
    if (hostname != null) {
        return hostname.startsWith("www.") ? hostname.substring(4) : hostname;
    }
    return hostname;
}

This above gives you the hostname, and is faultproof if your hostname does start with either hostname.com/... or www.hostname.com/..., which will return with 'hostname'.

If the given url is invalid (undefined hostname), it returns with null.