get protocol from URL if not typed in

Question

I am trying to find a way to get the protocol from a URL that the user types in. I have an EditText set as uri in an android layout file. The user types in his web address as www.thiersite.com or theirsite.com.

Now how can I get the correct protocol from what they have typed in? It seems everywhere I look that you need to have either https:// or http:// as the protocol in the http request. I get a malformed exception when I don't have a protocol for their web address.

Is there a way to check the URL without having the need to have the protocol when they typed their address? So in essence, do I need to ask the User to type in the protocol as part of the URL? I would prefer to do it programmatically.

Do you ever expect something other than http or https? If no, just add one of those. — mattm
– mattm, Commented Feb 15, 2015 at 15:51
Check whether string starts with "http". If not, add http:// — mattm
– mattm, Commented Feb 15, 2015 at 16:03

Community · Accepted Answer · 2017-05-23 10:24:12Z

1

/**
* Protocol value could be http:// or https://
*/
boolean usesProtocol(String url,String protocol){
    boolean uses = false;
    try{
        URL u = new URL( protocol.concat(url) );
        URLConnection con = u.openConnection();
        con.connect();
        // the following line will be hit only if the 
        // supplied protocol is supported
        uses = true;
    }catch(MalformedURLException e){
        // new URL() failed
        // user has made a typing error
    }catch(IOException e){
        // openConnection() failed
        // the supplied protocol is not supported
    }finally{
        return uses;
    }
}

I believe that the code is self-explaining. The above code uses no external dependencies. If you do not mind using JSoup, there is another answer on SO that deals with the same: Java how to find out if a URL is http or https?

My Source: http://docs.oracle.com/javase/tutorial/networking/urls/connecting.html

edited May 23, 2017 at 10:24

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answered Feb 15, 2015 at 15:51

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5 Comments

Dino Over a year ago

Am I correct in assuming that Java can not get a http request without the protocol in front of the URL such as https:// or http://? So a malformed exception will occur if www.theirsite.com does not have https:// or http:// in front of it?

An SO User Over a year ago

@Dino You are correct. You can read the docs here: docs.oracle.com/javase/7/docs/api/java/net/URL.html Also note that raising exceptions is an expensive process. Consider caching the URLs for further use.

Dino Over a year ago

I was wondering about that, I think I will not do this method and ask them to select https:// or http://

An SO User Over a year ago

The implementation is completely yours :)

Dino Over a year ago

Yes very true, just trying to develop for the "lazy user".

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