Regular expression for finding URL in Java String

Question

How do you modify the following regex:

String URLpattern   = "((https?|ftp|gopher|telnet|file|Unsure|http):((//)|(\\\\))+[\\w\\d:#@%/;$()~_?\\+-=\\\\\\.&]*)"

with one that takes into account ALL the following URL forms?

http://www.website.com
https://www.website.com
www.website.com
website.com
http://website.com
https://website.com

EDIT: There are a bunch of already proposed solutions to the problem. I can list some of them:

Regular expression to match URLs in Java
Regex to matches a url with or without http in java (nice since explained, however not working in my code)
Regular Expression, match url without "http://" and any other "/"

However, although I tried all of them too, none of them is proposing an explanation of how and why the expression works. Thus, whenever there is a malfunctioning (and to me, a malfunctioning was happening in urls in the form website.com and http://website.com), it becomes difficult for newbies (like me ;) ) to apply any modification or understand what is going on when there is a failure. A well explained solution is always better than a solution made by others and not replicable in the next time =)

Why did I get so many downvotes? I mean: I looked for other questions related to this topic but none of them is offering a functioning solution... If you think this is not a good question you should require to close it :) — Eleanore, May 02 '14 at 13:14
We want to see effort. If you've done research, show it and explain why it doesn't help you. — Sotirios Delimanolis, May 02 '14 at 13:29

sshashank124 · Accepted Answer · 2014-05-02T13:12:50.083

3

Given your list of websites, the following regex will do the trick:

(https?://)?(www\.)?\w+\.com

Demo

edited May 02 '14 at 13:12

answered May 02 '14 at 13:03

sshashank124

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I know the feeling you get when upvotes don't count after reaching 20 upvotes lol – Amit Joki May 02 '14 at 13:04
@DavidWallace, Thank you, Answer corrected. The /g might have tagged along by mistake when I was copying. from regex101.com – sshashank124 May 02 '14 at 13:13
And also: I guess Java requires two backslashes – Eleanore May 02 '14 at 13:15
1

@Eleanore Well, not exactly. Having a regexp in a String literal means you have to double the backslashes, because of the rules about how String literals work. If your regexp came from somewhere else (like being read in from a file), you wouldn't have to double the backslashes. – Dawood ibn Kareem May 02 '14 at 13:18
@Eleanore, If my answer was helpful, would you mind accepting it? Thank you. – sshashank124 May 03 '14 at 04:47

score 0 · Answer 2 · answered May 02 '14 at 13:14

Try this one, it works fine.TESTED with all your URLs!

private static final String URL_PATTERN = "(@)?(href=')?(HREF=')?(HREF=\")?(href=\")?(http://)?(https://)?" +
        "[a-zA-Z_0-9\\-]+(\\.\\w[a-zA-Z_0-9\\-]+)+(/[#&\\n\\-=?\\+\\%/\\.\\w]+)?";

private Pattern urlPattern =Pattern.compile(URL_PATTERN);

public boolean isURL(String url)
{
    boolean mat = urlPattern.matcher(url.trim().replace(" ","")).matches();
    return urlPattern.matcher(url.replace(" ","")).matches();
}

Regular expression for finding URL in Java String

2 Answers2