Get relevant part of domain name in Java

Question

If we have an url e.g www.google.de how can I get ONLY the "google"

In Java new URL (url).getHost(); does work but it gives me google.de and this is not what I want to have.

Thank you

EDIT: If we have something like www.google.co.uk then I also want to have only "google" as result.

I dont want "google.de" or "www.google" I ONLY want "google"

You're going to have to create your own rules. On what basis are you choosing "google" from "www.google.co.uk"? Second element? First element but ignoring "www" as a special case? What other special cases do you want to ignore? It's your requirement - you have to define it. — slim
– slim, Commented Jul 11, 2017 at 15:30
The part you want to ignore, i.e. the www actually is the hostname. — Björn Zurmaar
– Björn Zurmaar, Commented Jul 11, 2017 at 15:36
Stepping back, I think this is an XY problem. meta.stackexchange.com/questions/66377/what-is-the-xy-problem -- why do you want to do this? — slim
– slim, Commented Jul 11, 2017 at 15:47

17slim · Accepted Answer · 2017-07-11 15:48:56Z

1

Splitting on a period and selecting the first or second element (whichever is not "www") would work:

URL url = new URL("http://www.host.ext.ext");
String host = url.getHost(); // host = "www.host.ext.ext"
String splitHost = host.split("\\.") // splitHost = { "www", "host", "ext", "ext" }

host = splitHost[0].equals("www") ? splitHost[1] : splitHost[0]; // host = "host"

If there is anything more than http://www. before it, and the extension is potentially more than two "extensions" (.co.uk for instance), then there is no easy way to get just the part you want. As far as I know, you would have to try iterating over a list of extensions and return the part immediately before the longest matching extension.

edited Jul 11, 2017 at 15:48

answered Jul 11, 2017 at 15:33

17slim

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4 Comments

styfle Over a year ago

This works but I agree with the comment above that this is likely an XY Problem and there is missing information why "google" is more useful than "google.com".

17slim Over a year ago

Yeah, I think I agree as well now.

17slim Over a year ago

While it is possible this is an XY, I think it could also be exactly what they're asking. Perhaps they actually want to display the important part, ignoring the extension? Although that might be problem X now that I think about it; "how do I display a website's display name/title?"

17slim Over a year ago

Also, could anyone explain the downvote? The answer does exactly what the asker asked for, and explains the one possible pitfall. Help us out here.

PotatoManager · Accepted Answer · 2017-07-11 15:41:11Z

0

The most basic solution would be using

 System.out.println(url.split("\\.")[1]);

Or you could try this https://stackoverflow.com/a/23079402/2555419

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;
}

edited Jul 11, 2017 at 15:41

answered Jul 11, 2017 at 15:34

PotatoManager

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2 Comments

SLaks Over a year ago

He needs to specify his question, but he probably actually wants a ccTLD list.

PotatoManager Over a year ago

Yeah probably, I just gave him the most basic solution so he can have somewhere to start from if he wants to use String manipulation.

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