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 */

The future looks just as bright for information technology as it did ten years ago when this career field started growing in huge numbers due to major internet technological advances and the popularity of mobile devices such as the smartphone and eReaders like Amazon’s Kindle.  In classrooms and libraries across the nation, information technology has become instrumental in the way students learn and the way teachers give lessons, and thanks to online education more adults have access to a better education without incurring a lot of debt. Needles to say, the need for qualified workers in information technology will continue in times to come. Some of the technological careers that are rapidly growing in popularity in the last decade are a direct reflection of current trends.

Information Technology Managers

The information technology manager is responsible for handling all computer activities for a business and performs upgrades on computer software and hardware, installs new security features on computers, creates budgets and goals for the IT department, supervises other IT employees and troubleshoots computers when needed. According to the Bureau of Labor Statistics, there were 332,700 information technology management jobs filled in 2012 and a majority of these positions were in the computer systems sector. Most information technology managers hold a bachelor's degree in computer science or information technology, and a growing number of employers prefer a graduate degree. The job growth is expected to grow at 15% between now and 2022.

Mobile Application Developers

This job will grow by leaps and bounds as millions of people continue to purchase mobile devices and download apps for business and entertainment purposes. It creates expanded opportunities for those who want to become mobile application developers. A mobile application developer often works with other developers to create mobile-friendly apps or mobile-friendly versions of business websites for consumers. The developer may have his own firm or he may be employed with a larger company, and he will need to understand the basics of web design and different kinds of codes to succeed in this career. The Bureau of Labor Statistics states that the job growth is expected to be at 28% by 2020.

Health Information Technology

Another fast growing sector within information technology is health information technology and there are various jobs to choose from. You can work with health insurance providers and your duties would include processing patients' insurance claims and managing patients' insurance information using a computer database. Another option is to work as a medical biller in a doctor's office preparing patient’s invoices. The good thing about these jobs is that you do not need a four-year degree to get the training; you can obtain a two-year associates degree or a certificate in health information technology.

Search Engine Optimization Consultant

This is an important information technology career because most businesses have websites and if these websites are going to receive high traffic from visitors and earn profit, proper search engine optimization is necessary. The SEO consultant's job is to ensure that a business website gets high rankings on the major search engines and plenty of traffic from visitors. A good SEO consultant at a minimum will know how to research keywords effectively and implement these into the website's content based on the website's theme and he would utilize web analytics as part of the job. An SEO consultant may work on a freelance basis or be employed with an advertising company as an example.

Best Cities for Technology Careers

If you're thinking about relocating for your career, here are some of the best cities currently for information technology jobs listed in Forbes. 

Although reports made in May 2010 indicate that Android had outsold Apple iPhones, more recent and current reports of the 2^nd quarter of 2011 made by National Purchase Diary (NPD) on Mobile Phone Track service, which listed the top five selling smartphones in the United States for the months of April-June of 2011, indicate that Apple's iPhone 4 and iPhone 3GS outsold other Android phones on the market in the U. S. for the third calendar quarter of 2011. This was true for the previous quarter of the same year; The iPhone 4 held the top spot.  The fact that the iPhone 4 claimed top spot does not come as a surprise to the analysts; rather, it is a testament to them of how well the iPhone is revered among consumers. The iPhone 3GS, which came out in 2009 outsold newer Android phones with higher screen resolutions and more processing power. The list of the five top selling smartphones is depicted below:

1. Apple iPhone 4
2. Apple iPhone 3GS
3. HTC EVO 4G
4. Motorola Droid 3
5. Samsung Intensity II[1]

Apple’s iPhone also outsold Android devices7.8:1 at AT&T’s corporate retail stores in December. A source inside the Apple company told The Mac Observer that those stores sold some 981,000 iPhones between December 1st and December 27^th 2011, and that the Apple device accounted for some 66% of all device sales during that period (see the pie figure below) . Android devices, on the other hand, accounted for just 8.5% of sales during the same period.

According to the report, AT&T sold approximately 981,000 iPhones through AT&T corporate stores in the first 27 days of December, 2011 while 126,000 Android devices were sold during the same period. Even the basic flip and slider phones did better than Android, with 128,000 units sold.[2] However, it is important to understand that this is a report for one particular environment at a particular period in time. As the first iPhone carrier in the world, AT&T has been the dominant iPhone carrier in the U.S. since day one, and AT&T has consistently claimed that the iPhone is its best selling device.

Chart courtesy of Mac Observer: http://www.macobserver.com/tmo/article/iphone_crushes_android_at_att_corporate_stores_in_december/

A more recent report posted in ismashphone.com, dated January 25 2012, indicated that Apple sold 37 million iPhones in Q4 2011.  It appears that the iPhone 4S really helped take Apple’s handset past competing Android phones. According to research firm Kantar Worldpanel ComTech, Apple’s U.S. smartphone marketshare has doubled to 44.9 percent.[3] Meanwhile, Android marketshare in the U.S. dropped slightly to 44.8 percent. This report means that the iPhone has edged just a little bit past Android in U.S. marketshare. This is occurred after Apple’s Q1 2012 conference call, which saw themselling 37 million handsets. Meanwhile, it’s reported that marketers of Android devices, such as Motorola Mobility, HTC and Sony Ericsson saw drops this quarter.

Cloud computing is the recent rage in the IT industry. According to the report by Forbes, the estimated global market for cloud computing is expected to reach $35.6 billion in 2015, from the $12.1 billion market of 2010.

How it began

The idea of cloud computing was inspired by the concept of “utility computing” which introduced the idea of computing using the virtual servers. These virtual servers do not actually exist anywhere physically and can be moved anywhere without causing any disturbance to the end users. Thus it minimizes the cost involved on the devices to a great extent and provides innumerable benefits to the companies that adopt this system.

Cloud Computing Types