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,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */ 

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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Programming and Extremism

InPursuit

The evils of extremism are evident from code. Good code is written efficiently, doing only what is required to accomplish the task. Good code is written incrementally, making small changes over time.

In life, nature abhors extremes. Extremists follow single-minded goals, going far beyond what is necessary to handle the problems it seeks to solve. Unlike good code, extremism is incredibly inefficient. Good code remains efficient, accomplishing its task and exiting.

If leaders would become like code, the world would be a better place. Politicians budget great resources and establish new programs to accomplish their tasks. Good code only devotes the necessary resources to the task at hand.

If the world of people worked like good code, all things would benefit.

Pursuing a Dream Written in Code


InPursuit
What is this dream?

It all started years ago, when I was in my late teens. My friend, Bill, had a computer. I was enthralled with the things he could do with it. It was amazing to see the things he programmed on his Apple computer. I think it was the iie but I don’t remember the model number for sure. Unfortunately, Bill didn’t see his dream of being a programmer. He died of leukemia when he was about 18 or 19 years old. I think he would have been a great contributor to excellence in the computer-driven world we have today.

I’ve wandered my own path in life but computers and music have always been of prime importance. I tried computer programming when I was younger but the math classes discouraged me. I’ve taught music forever, own and operate my own business that does a variety of media production (including music and video) and teaches music and art in our local community. I worked as a technical writer for a number of years, went to school for music and to learn the business of the entertainment industry, and also write and manage the company’s web pages. My interest in programming has never left but my own near death experience in November 2012 has given me an enhanced appreciation of life and the impetus to do the things I’ve wanted to do for a long time.

So, Here’s the Plan

I am currently doing websites in PHP and HTML (my strongest web languages), with MySQL and CSS (necessary companions) and a smattering of Javascript (my weakest language and the closest to being my nemesis). I will be working to update these skills as I go in my daily work.

The areas of interest I have in learning and using additional languages include refreshing my knowledge of C, continuing in C++ and getting farther with Java than I have gone. I learned C years ago but got stuck on pointers. How silly that seems now. I didn’t get very far with C++; I’m going through the tutorial now and can tell you that a couple of years makes a big difference. I stopped for a while in Java but need to go through all the object oriented stuff more fully.

Will You Join Me on My Journey?

I will be posting about my journey here as I strive to become a better programmer. It doesn’t mean I will only post about computer programming. I will also be posting about music, my other great passion, and the two great things you are never supposed to discuss in polite company, namely, religion and politics. You are welcome to join me as I continue a journey that is years in the making. There may be wisdom and wit; that often happens when I’m at my best. You may also, from time to time, catch me at my worst. I hope you will gain something from every minute of it.