Regular Expression to Find URLs in Java

I’ve been learning how to use regular expressions in Java and found that it’s hard to get some of the code working properly from tutorials and places like Stack Overflow. I thought it might be handy to provide a working script in Java that can return multiple URLs from a string.

So, I’ve modified code from Oracle’s tutorial on regular expressions, using a slight variant a regular expression I found on Stack Overflow. This class prompts you to input a string, then evaluates the string, returning all the URLs in the string. It does this by searching for href=”[any characters in the url]” and returning each instance of this in a separate line on the screen.

This code can easily be modified as a starting point for evaluating source code returned by a spider for evaluating links on a website. I hope it is useful for you.

/*
 * THIS WORK IS A DERIVATIVE OF CODE COPYRIGHTED BY ORACLE.
 * YOU MAY USE THIS WORK FREELY UNDER THE CONDITIONS OF THE ORACLE COPYRIGHT.
 * THE AUTHOR OF THE DERIVATIVE CODE DOES NOT REQUIRE ANY FURTHER ATTRIBUTION
 *
 * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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import java.io.Console;
import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class RegexURL {
    public static void main(String[] args){
        Console console = System.console();
        if (console == null) {
            System.err.println("No console.");
            System.exit(1);
        }
        while (true) {
            Pattern pattern = 
            Pattern.compile("href=\"(.*?)\"");

            Matcher matcher = 
            pattern.matcher(console.readLine("Enter input string to search: "));

            boolean found = false;

            while (matcher.find()) {
                console.format("%s\n",
                    matcher.group(),
                    matcher.start(),
                    matcher.end());
                found = true;
            }

            if(!found){
                console.format("No match found.%n");
            }
        }
    }
}
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