Regular expression to match URLs in Java

user_2138 0
Viewed 231763

I use RegexBuddy while working with regular expressions. From its library I copied the regular expression to match URLs. I tested successfully within RegexBuddy. However, when I copied it as Java String flavor and pasted it into Java code, it does not work. The following class prints false: 

public class RegexFoo {

    public static void main(String[] args) {
        String regex = "\\b(https?|ftp|file)://[-A-Z0-9+&@#/%?=~_|!:,.;]*[-A-Z0-9+&@#/%=~_|]";
        String text = "http://google.com";
        System.out.println(IsMatch(text,regex));
}

    private static boolean IsMatch(String s, String pattern) {
        try {
            Pattern patt = Pattern.compile(pattern);
            Matcher matcher = patt.matcher(s);
            return matcher.matches();
        } catch (RuntimeException e) {
        return false;
    }       
}   
}

Does anyone know what I am doing wrong?

regexbuddy regex java
11 Answers

Try the following regex string instead. Your test was probably done in a case-sensitive manner. I have added the lowercase alphas as well as a proper string beginning placeholder.

String regex = "^(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]";

This works too:

String regex = "\\b(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]";

Note:

String regex = "<\\b(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]>"; // matches <http://google.com>

String regex = "<^(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]>"; // does not match <http://google.com>
TomC_131830

I'll try a standard "Why are you doing it this way?" answer... Do you know about java.net.URL?

URL url = new URL(stringURL);

The above will throw a MalformedURLException if it can't parse the URL.

Bill_James_138240

This works too:

String regex = "\\b(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]";

Note: 

String regex = "<\\b(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]>"; // matches <http://google.com>

String regex = "<^(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]>"; // does not match <http://google.com>

So probably the first one is more useful for general use.

user_21380
user_116361960

When using regular expressions from RegexBuddy's library, make sure to use the same matching modes in your own code as the regex from the library. If you generate a source code snippet on the Use tab, RegexBuddy will automatically set the correct matching options in the source code snippet. If you copy/paste the regex, you have to do that yourself.

In this case, as others pointed out, you missed the case insensitivity option.

Jan_Goyvaerts_333580

Here is a proposal of an URL parser regex that recognizes :

  • Protocol
  • Host
  • Port
  • Path (Document/folder)
  • Get parameters
^(?>(?<protocol>[[:alpha:]]+(?>\:[[:alpha:]]+)*)\:\/\/)?(?<host>(?>[[:alnum:]]|[-_.])+)(?>\:(?<port>[[:digit:]]+))?(?<path>\/(?>[[:alnum:]]|[-_.\/])*)?(?>\?(?<request>(?>[[:alnum:]]+=[[:alnum:]]+)(?>\&(?>[[:alnum:]]+=[[:alnum:]]+))*))?$

This regex is able to parse an URL such :

jdbc:hsqldb:hsql://localhost:91/index.

There can be many way to engineer a URL regex, thus the one I propose can be lightly adapted to match more accurate URL grammars.

It can be tested on the following page : https://regex101.com/r/Dy7HE0/5

Be aware that langages native API for regex (such as java.util.regex) don't support smart character classes such as [[:alnum:]] and [[:alpha:]].

Use instead \w and \d.

user_72012920

First, an regex example:

regex = “((http|https)://)(www.)?” 
+ “[a-zA-Z0-9@:%._\\+~#?&//=]{2,256}\\.[a-z]” 
+ “{2,6}\\b([-a-zA-Z0-9@:%._\\+~#?&//=]*)”

*The URL must start with either http or https and *then followed by :// and *then it must contain www. and *then followed by subdomain of length (2, 256) and *last part contains top level domain like .com, .org etc.

In JAVA

// Java program to check URL is valid or not
// using Regular Expression
 
import java.util.regex.*;
 
class GFG {
 
    // Function to validate URL
    // using regular expression
    public static boolean
    isValidURL(String url)
    {
        // Regex to check valid URL
        String regex = "((http|https)://)(www.)?"
              + "[a-zA-Z0-9@:%._\\+~#?&//=]"
              + "{2,256}\\.[a-z]"
              + "{2,6}\\b([-a-zA-Z0-9@:%"
              + "._\\+~#?&//=]*)";
 
        // Compile the ReGex
        Pattern p = Pattern.compile(regex);
 
        // If the string is empty
        // return false
        if (url == null) {
            return false;
        }
 
        // Find match between given string
        // and regular expression
        // using Pattern.matcher()
        Matcher m = p.matcher(url);
 
        // Return if the string
        // matched the ReGex
        return m.matches();
    }
 
    // Driver code
    public static void main(String args[])
    {
        String url
            = "https://www.superDev.org";
        if (isValidURL(url) == true) {
            System.out.println("Yes");
        }
        else
            System.out.println("NO");
    }
}

In python 3

# Python3 program to check
# URL is valid or not
# using regular expression
import re
 
# Function to validate URL
# using regular expression
def isValidURL(str):
 
    # Regex to check valid URL
    regex = ("((http|https)://)(www.)?" +
             "[a-zA-Z0-9@:%._\\+~#?&//=]" +
             "{2,256}\\.[a-z]" +
             "{2,6}\\b([-a-zA-Z0-9@:%" +
             "._\\+~#?&//=]*)")
     
    # Compile the ReGex
    p = re.compile(regex)
 
    # If the string is empty
    # return false
    if (str == None):
        return False
 
    # Return if the string
    # matched the ReGex
    if(re.search(p, str)):
        return True
    else:
        return False
 
# Driver code
 
# Test Case 1:
url = "https://www.superDev.org"
 
if(isValidURL(url) == True):
    print("Yes")
else:
    print("No")
user_157957230

This regular expression works for me:

String regex = "(https?://|www\\.)[-a-zA-Z0-9+&@#/%?=~_|!:.;]*[-a-zA-Z0-9+&@#/%=~_|]";
user_127879360
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