String results = "";
for(char c: String.toCharArray()) {
results += (char)(c+3);
}

and

StringBuilder results = new StringBuilder();
for(char c: String.toCharArray()) {
results.append((char)(c+3));
}

He then proceeded to convert the entire collection of works by Shakespeare. Method 1 was estimated to take over 21 days by the computer. Method 2 finished in seconds. That caught my attention.
There are several cool data structures and search techniques that I have found awesome throughout this semester.

Binary Search

The people who write these algorithims are brilliant. To search through a sorted array, why look at every element? Why not just jump to the middle, see if what you are looking for is less than or greater than the middle, then do it again, with the new middle being the middle of the selected half.

ArrayList

ArrayList’s is essentially a circular array that handles the dirty details of dealing with arrays. When programming simple projects, I prefer to use ArrayLists as they are just more friendly than arrays. It dynamically resizes to allow you to constantly add without having to handle the actual details of expanding the underlying arrays. Finding an element at a certain element is VERY cheap as it essentially an array wrapper, the problem with ArrayList is removing or adding as it requires all of the following elements to be moved which can be pricey in a large array (I don’t mean hundreds, I mean hundreds of thousands).

LinkedList

LinkedList’s can be awesome when used correctly. A LinkedList is a group of nodes, linearly linked together. Node A contains certain data and a link to B. B contains data and a link to C, etc. This can be quite efficient if all you need to do is traverse the list in order. Finding a certain index can be much more costly than an ArrayList, but adding and removing at the end, or having a certain Node is extremely cheap. While sounding sort of lame, it can be very useful.

Tries

Now Trie’s really got my attention the first day of class. While looping through every String in a String[] can be very expensive, say an 80,000 word dictionary. While a binary search can cut that down to around 30 loops. Imagine if you could do that in 5 for a 5 letter word, or 8 for an 8 letter word. Imagine a tree, with the head having 26 children, each corresponding to a letter. From each letter are more children, and more children from there. Say following from the root, ‘a’ to ‘c’ to ‘e’, and ‘e’ contains a ‘emptyString’ property that holds the boolean true. You have found the word ‘ace’ in 3 actions. Mind boggling.

Conclusions

Knowing these staples of data structures enables you to mix and mash creating the perfect data structure for any ocassion. Today I mixed LinkedLists with float arrays to efficiently store millions of floating point numbers so that I could both stay memory efficient (arrays of primitive types) while keeping object sizes down (breaking the large arrays up through the LinkedLists). Note: I in no way claim to be a genius on this, or even know a good amount about it, as I have only spent a few months studying it, but it’s some awesome stuff that all developers should look into if they haven’t already.

So I need to verify it, the main and recommended way is to use TXT record supported by most domain name registrars. Well mine wasn’t supported. Shouldn’t be a problem, all I need to do is upload an HTML file to a server behind the domain name to verify. That is quite dificult it turns out.

Next I fire up a VM, put a web server on it, put the verification file on it, and open it to the world and put it in the DNS settings for the domain name. Cox Communications doesn’t allow port 80; FAIL.

Try two, I’ll do a redirect from my domain name to a file on jtmcgee.net projects. FAIL, Google Apps doesn’t allow redirects when looking for the verification file.

3rd times the charm, right? I’ll CNAME my App Engine and put my project there. FAIL, the App Engine just redirects me to google.com.

4th time I try to CNAME my own website. This has a similar result, getting redirected back to epicserve.com, the owner of the servers website.

5th time, I contacted my friend Brent and asked him to work some config magic so that I could CNAME my project server without redirecting. Finally I can validate!

Yet I am still waiting for that CNAME change to propogate to the DNS servers around the world… 1and1 is famous for their slowness. It shows up right on my computer I am just waiting for it to show up right at Google.

Never thought something so simple would take so long.

The Happy Birthday Facebook App was designed for lazy people, me in mind, that want to post on peoples walls at midnight for their birthday so it can be special and all, but for one reason or another they can’t. This app basically lets you choose friends to wish happy birthday to at midnight, set a custom message, and adds it to the database to wait for that special night when it strikes 12. Then it will use that access token you gave it long ago and write on their birthday giving them your special message.

Like a large majority of my projects, it is open sourced.  You can find it at GitHub and do whatever you want with the source. If you are looking for a simple Java Facebook app example or a simple Java App Engine app example, then it’s for you.

Try it out on Facebook.

This year I moved the project to GitHub and you can find it here. This years version features an install script that dramatically makes it simpler to setup. Once you clone the git repository just running the install.php will setup everything from the MySQL DB, to error reporting, to your Google Maps API (for the map on the geo-location). All that’s needed to install this correctly is giving the web server the ability to write/edit files.

If you have a plugin for eclipse that you release check it out. Worst case scenario is it breaks, and if that happens it will turn itself off, stop logging, and allow the downloads to continue as if it was never there. Check it out.

Now for this application, as I wrote it in a matter of days and released it the day of schedule releases, I had to go with a language I knew very well, and I had to have a reliable, dependable source to host it at. I automatically though of the Google App Engine as it is pretty sweet to play around with and now would be a great time to test it in a live environment. My previous application I had wrote on Google’s free, scalable engine was written in Python. It utilized the amazing Django framework, but I felt like I didn’t really understand the Python language as well as some others. The only other option for selection on the App Engine was Java. This was perfect as I had just completed a summer class on Java and it was extremely fresh in my mind.

Core Java Servlets

Now coming from PHP for web development the idea of Servlets and JSP’s was totally a different way of thinking. With PHP I was used to putting what code I needed to on each page to achieve what needed to be done. With a bit of Python/Django experience, Java’s way was still different, but not as different as PHP to Java. Java’s JSP method reminded me a lot of Django templates, except that JSP’s are a load more powerful. As Django templates (at least from my experience) only allow a few tags, a JSP allows practically any Java code (that would normally go inside a main method) and allows imports and special features unique to JSP’s, like includes. JSP’s includes in fact reminded me some more of Django’s templates with all the splitting up possible of the HTML files.

Now that we briefly know what a JSP is, a servlet is just like a Java class that implements the standard Apache servlet. Within these servlets you have two methods by default doGet(HttpServletRequest req, HttpServletResponse resp) and doPost() with the same arguments. There are a few differences from a standard Java class beyond those previously noted:

resp.getWriter().println(); // to print to the screen you must get the PrintWriter via the resp.getWriter() method
resp.setContentType("text/html"); // must do if you print out any HTML and don't want it to appear as standard text
resp.sendRedirect(String url); // a simple way to send a user to be redirected

There is (obviously) no console input on a web browser, so the standard way to get input via the web is through GET and POST methods. These are handled via the corresponding doGet() and doPost() methods. Now to actually get the value passed, you must know the variable name and use it accordingly.

req.getParameter(String paramName); // where paramName is the ?name=Joe&age=18 name or age

Sometimes you will also find yourself in need of getting an array, from say a multiple choice drop down.

req.getParameterValues(String paramName); // just once and it will return a String[]

Now onto more of the theory behind servlets, and less of the syntax. Now please remember when I say theory, this is just the way I perceive it. In my application if I would have a full blown HTML page, I would always put it in a JSP as it is so simple and better looking. However when there was a simpler page that had a bit more code behind it, I would make that a servlet. An example of a simpler page with more code that I used as a servlet would be my form handlers (any adding or updating interaction with the database), and also I handled the OAuth authentication with servlets.

JSP’s

JSP’s, or Java Server Pages, are a mix between Java code & client-side scripting. It allows you to mix the power of Java and your the models in your MVC framework with the simplicity of a HTML file. You probably see them all over the web, as they are quite effective, especially in larger businesses and universities.
I have not personally gone that far into all the powers of JSP’s but enough to know that I like them. I am not going to try and write a tutorial but just point out a few things I use and a good tutorial or two.
Now one of the simplest, but greatest is the server-side include of static content. This allows you to keep your web pages on the server side leaner and able to easily change base things like headers or footers.

<%@ include file="/include.html" %>

Other useful things to know, if you need to get any parameters or need to mess with the request or response, they are simply called request and response in all JSP’s. So you could use a request.getParameter("id"); for example.
If you need to write anything to the page from within the Java code just throw a out.println(String value); or out.print(String value).

For anything more than what I included check Google for some JSP tutorials or here is a good looking one.

Benefits

I see there being several benefits of using Java as the language behind more complex applications because of it is an object oriented language. It being OO allows code to get so many more times complex. Now, in web development at least, a OO language is only as good as the database that supports it . I happened to be very lucky with Google App Engine as it was powered by a OO database allowing me to store some of my unique data types like “Student”, “Teacher”, “Course”, and “Schedule” in the database and retrieve it like it has been open since it was created. Most of the interface for this was provided in the JDO classes in javax.JDO.
With this and a few classes for getting and selecting certain Students/Teachers/Courses, it was very easy to get exactly the results I want in a few lines of code in a JSP. And I know that in Python and PHP you can have classes and objects, but it’s just not the same as it is in Java. While Java can be pretty strict with it’s types and defining them, it in turn gives a lot of power to create awesome and dynamic applications for the end user.

Finally

As I have been reading in my “Clean Code” book, it is better to take longer and write software better the first time. Better being Javadoc’d and Object-Oriented. If you were to write it the other way, with say PHP or Python and have each script access the relational database, get the results, sort the results into the data you need, and output it correctly, that is so much code duplication. One script could be anywhere from 20% – 50% of the same code over and over, why not just write it great in the beginning in an OO way so the only code duplication you have is one or two lines to load the pre-written-by-you libraries that does all that work in one place, one time.

And sorry Brent I think I like Java Servlets & JSP’s a wee bit more than Python/Django even though I think Django is a great framework and would love if it were written in Java instead, Python just isn’t as big and powerful as Java.

My application, only available for MHS students, allows you to add your schedule (teachers and classes), see who’s in your class, comment and Facebook Like both your teachers and your hours.

It was written on the Google App engine, using an OO (object oriented) database with JSP’s and Core-servlets. I  will be writing a post about this stuff later.

For some who want to complain about how “bad” it is, I remind you this was about 8 days of work. However here is some of my attached code for it. Note: this is only SOME, not all.

socialschedulesSource [zip]

1. Download & Unzip
2. Put it into /home/youruser/scripts ( so tweet and twitter and etc. are in that directory )
3. sudo bash install.sh ( it will try to install php5-curl if you don’t have it, you need this )
4. . ~/.bashrc ( include the period at the beginning )
5. setupTwitter twitterusername twitterpassword
6. You may now use twitter to view the 5 latest tweets or tweet “YOUR Text here“ to tweet something

Download [tar.gz]

Download [zip]

Download [tar]

Download FlickrDownloadR

( It’s kind of slow, but it gets the job done! )

Eclipse Plugin Download Log [download]

Have a shot at it, it is very low in smarts but it is building. This project was made by jtmcgee.net projects.