I will begin our blog on Java Tutorial with an incredibly important aspect of java development:  memory management.  The importance of this topic should not be minimized as an application's performance and footprint size are at stake.

From the outset, the Java Virtual Machine (JVM) manages memory via a mechanism known as Garbage Collection (GC).  The Garbage collector

• Manages the heap memory.   All obects are stored on the heap; therefore, all objects are managed.  The keyword, new, allocates the requisite memory to instantiate an object and places the newly allocated memory on the heap.  This object is marked as live until it is no longer being reference.
• Deallocates or reclaims those objects that are no longer being referened. 
• Traditionally, employs a Mark and Sweep algorithm.  In the mark phase, the collector identifies which objects are still alive.  The sweep phase identifies objects that are no longer alive.
• Deallocates the memory of objects that are not marked as live.
• Is automatically run by the JVM and not explicitely called by the Java developer.  Unlike languages such as C++, the Java developer has no explict control over memory management.
• Does not manage the stack.  Local primitive types and local object references are not managed by the GC.

So if the Java developer has no control over memory management, why even worry about the GC?  It turns out that memory management is an integral part of an application's performance, all things being equal.  The more memory that is required for the application to run, the greater the likelihood that computational efficiency suffers. To that end, the developer has to take into account the amount of memory being allocated when writing code.  This translates into the amount of heap memory being consumed.

Memory is split into two types:  stack and heap.  Stack memory is memory set aside for a thread of execution e.g. a function.  When a function is called, a block of memory is reserved for those variables local to the function, provided that they are either a type of Java primitive or an object reference.  Upon runtime completion of the function call, the reserved memory block is now available for the next thread of execution.  Heap memory, on the otherhand, is dynamically allocated.  That is, there is no set pattern for allocating or deallocating this memory.  Therefore, keeping track or managing this type of memory is a complicated process. In Java, such memory is allocated when instantiating an object:

String s = new String();  // new operator being employed
String m = "A String";    /* object instantiated by the JVM and then being set to a value.  The JVM
calls the new operator */

As someone who works in many facets of the music industry, I used to seethe with a mixture of anger and jealousy when I would hear people in more “traditional” goods-based industries argue in favor of music content-based piracy. They made all the classic talking points, like “I wouldn’t spend money on this artist normally, and maybe if I like it I’ll spend money on them when they come to town” (which never happened), or “artists are rich and I’m poor, they don’t need my money” (rarely the case), or the worst, “if it were fairly priced and worth paying for, I’d buy it” (not true).  I always wondered if they’d have the same attitude if 63% of the things acquired by customers in their industries weren’t actually paid for, as was conservatively estimated as the case for the music industry in 2009 (other estimations put the figure of pirated music at 95%). Well, we may soon see the answer to curiosities like that. Though one can say with tentative confidence that music piracy is on the decline thanks to services like Spotify and Rdio, it could be looming on the horizon for the entire global, physical supply chain. Yes, I’m talking about 3d printers.

Before I get into the heart of this article, let me take a moment to make one thing clear: I think these machines are incredible. It’s damn near inspiring to think of even a few of their potentially world-changing applications: affordable, perfectly fit prosthetic limbs for wounded servicemen and women; the ability to create a piece of machinery on the spot instead of having to wait for a spare to arrive in the mail, or en route if your car or ship breaks down in a far away place; a company based out of Austin, TX even made a fully functioning firearm from a 3d printer a few months ago.

If these machines become as consumer-friendly and idiot-proof as possible (like computers), it’s possible that in a matter of decades (maybe less), a majority of U.S. households will have their own 3d printer. There’s also the possibility they could take the tech-hobbyist path, one that is much less appealing to the masses. Dale Dougherty of Makezine.com estimates there are currently around 100,000 “personal” 3d printers, or those not owned for business or educational purposes. I don’t think they’ll ever be as ubiquitous as computers, but there are plenty of mechanically inclined, crafty hobbyists out there who would love to play around with a 3d printer if it was affordable enough.

That being said, is there reason to worry about the economic implications of consumers making what they want, essentially for free, instead of paying someone else to produce it? Or will the printers instead be used for unique items more so than replicating and ripping off other companies’ merchandise in mass amounts? The number of people working in industries that would be affected by a development like this is far greater than the number of people who work in content-based industries, so any downturn would probably have a much larger economic implications. Certainly, those times are a ways off, but a little foresightedness never hurt anyone!

There are many excellent opportunities for IT professionals to present themselves to corporate entities for future consulting positions. You can find yourself in your next consulting engagement if you are willing to combine your IT skill-set, a good amount of corporate research and a bit of old fashioned moxie. Contrary to popular practice for applying for jobs through placement agencies and recruiters, it’s possible to meet with hiring managers, representing your firm, you, directly.

Although recruiters may not take a fee directly from you, the fact that they charge a fee for their services to a company after your placement may keep them from being able to place you. On the other hand, corporations searching for individuals with advanced knowledge of IT functions cannot rely on the friends and family of current employees to find superior consults in all fields.

What are some other options? First take the time to research corporations you would like to consult with. Look for the ones that most likely are complementary to your area of expertise because of the goods they produce or the services they provide to the public. Or you may opt to choose a company that is geographically close to where you live for the convenience of a short daily commute.  

Another way to find your next consulting job is to actively scan the news and see what corporations are making waves within their individual marketplaces. This is a good indicator of possible expansion and the need to hire on a contractual basis. Another good indicator of a need for IT professionals is a mention of a company relocation or expansion. Growth or renovation of office environments is often accompanied by a modernization of IT systems. Current IT team members may not be relocating or might not be familiar with systems other than the ones they already service.

Do as much research as possible about each corporation from their own websites and other sources dedicated to their particular field of endeavor. This gives you the edge in being able to speak about the IT systems they already have in place or your ideas for adapting their line of work or new product with the use of an IT system advancement. Their websites will often have a list of their corporate management. Make sure you address your cover-letter and resume to not only the Director of Human Resources, but to all executives in charge of their IT departments. Be specific in your abilities and the fact that you can be flexible with hiring arrangements.

Attend job fairs that have an emphasis on the more technical fields. When possible, also circulate your resume both digitally and in paper format to smaller and mid-sized companies. These corporations may not be able to maintain their own full-time IT group for fiscal reasons and your consulting prowess may be able to “save the day” for them in an emergency. You can become part of a corporate team on your own; all it takes is additional work on your part. However after your consultant job placement, you will be pleased that your efforts have succeeded so well.

Every programming language has a mechanism to allow the programmer to create variables which hold custom data entered in by either the coder themselves or by the user of the application.

Regardless of whether you’re new to programming or not, you will have used variables and you should understand that in javascript they can hold any value such as a number or a string of text.

There is also another type of variable called an Array. Now, depending on who you talk to, some will say an array is actually an object, while others say it is a variable. Neither one is wrong but for the sake of simplicity we’ll refer to it as a variable.

Now, arrays are special because they can hold multiple values as opposed to standard variables which can only hold a single value at one time. If you can, try and imagine that your computer’s memory is made up of thousands of little boxes, and each of those boxes has an address which javascript will use to retrieve the array values when needed.