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Blog Entries publications that: entertain, make you think, offer insight
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 */
I suspect that many of you are familiar with the term "hard coding a value" whereby the age of an individual or their location is written into the condition (or action) of a business rule (in this case) as shown below:
if customer.age > 21 and customer.city == 'denver'
then ...
Such coding practices are perfectly expectable provided that the conditional values, age and city, never change. They become entirely unacceptable if a need for different values could be anticipated. A classic example of where this practice occurred that caused considerable heartache in the IT industry was the Y2K issue where dates were updated using only the last 2 digits of a four digit number because the first 2 digits were hard-coded to 19 i.e. 1998, 1999. All was well provided that the date did not advance to a time beyond the 1900’s since no one could be certain of what would happen when the millennia arrived (2000). A considerably amount of work (albeit boring) and money, approximately $200 billion, went into revising systems by way of software rewrites and computer chip replacements in order to thwart any detrimental outcomes. It is obvious how a simple change or an assumption can have sweeping consequences.
You may wonder what Y2K has to do with Business Rule Management Systems (BRMS). Well, what if we considered rules themselves to be hard-coded. If we were to write 100s of rules in Java, .NET or whatever language that only worked for a given scenario or assumption, would that not constitute hard-coded logic? By hard-coded, we obviously mean compiled. For example, if a credit card company has a variety of bonus campaigns, each with their own unique list of rules that may change within a week’s time, what would be the most effective way of writing software to deal with these responsibilities?
People are optimistic about problem solving, but in most cases this is easier said than done. How do you do it?
In Adobe’s 2016 global study on creativity in business, 96% of people identified creativity as essential to their success, both in terms of their income and the value they bring to the world. Moreover, 78% wished they were capable of thinking differently, believing that they would progress through their careers more quickly if they did.
According to Malcom Gladwell, the world's most successful people have one thing in common: they think differently from most everyone else. In his book, How Successful People Think, Malcom opens with the following: “Good thinkers are always in demand. A person who knows how may always have a job, but the person who knows why will always be his boss. Good thinkers solve problems, they never lack ideas that can build an organization, and they always have hope for a better future”
Too often we attribute creative and “different” thinking to natural, innate characteristics that belong only to the lucky. The truth is that you can study how ridiculously successful people think and incorporate their approach into your world.
Snippets and Quotes from Tech Innovators.
In most business circles, the question of whether or not a website truly helps a company's business has become somewhat moot. Simply put, a website is a necessary evil, like it or not. The question is no longer, should a company have a website, but rather, is the website optimized to ensure the best potential results. Of course, it is important to understand what is meant by "helping a company."
Many businesses are under the assumption that a website is going to turn into cold hard cash for the company. Well, that could be the case if the organization is using a type of e-commerce platform to buy and sell goods. Many businesses are service oriented and as such, the website serves an entirely different purpose.
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The Hartmann Software Group understands these issues and addresses them and others during any training engagement. Although no IT educational institution can guarantee career or application development success, HSG can get you closer to your goals at a far faster rate than self paced learning and, arguably, than the competition. Here are the reasons why we are so successful at teaching:
- Learn from the experts.
- We have provided software development and other IT related training to many major corporations since 2002.
- Our educators have years of consulting and training experience; moreover, we require each trainer to have cross-discipline expertise i.e. be Java and .NET experts so that you get a broad understanding of how industry wide experts work and think.
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- Save on travel expenses by learning right from your desk or home office. Enroll in an online instructor led class. Nearly all of our classes are offered in this way.
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- See the big picture and have the instructor fill in the gaps
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