This is one of the frequently asked questions from Scala interviews. Even though both var and val keyword is used to declare variables in Scala there is a subtle difference between them. A var is a variable. It’s a mutable reference to a value. Since it’s mutable, its value may change through the program lifetime. On the other hand, val keyword represents a value. It’s an immutable reference, meaning that its value never changes. Once assigned it will always keep the same value. It’s similar to a final variable in Java or constants in other languages. It's also worth to remember that the variable type cannot change in Scala. You may say that a var behaves similarly to Java variables.
If you are preparing for Oracle Java SE 8 Certifications e.g. OCAJP8 and OCJP8, also known as exam 1Z0-808 and 1Z0-809 and looking for some free practice tests then you have come to the right place. In this article, I am going to share some of the best OCAJP 8 and OCPJP 8 mock tests available for free of cost online, so that you can check your speed and accuracy before the real exam. These tests are not just useful for Oracle's Java OCA and OCP certification but also for upgrade exams like OCJP 8 upgrade exams with code 1Z0-810 and 1Z0-813, upgrade to Java SE 8 from Java 6 and prior version. Many of these practice tests are like web simulator where you need to solve a relatively small number of questions within 45 to 60 minutes. The web simulator also includes timer so that you can finish these free mock tests on time.
In the last article, I have shown you how to implement post order traversal in a binary tree using recursion and today I am going to teach you about post order traversal without recursion. To be honest, the iterative algorithm of post-order traversal is the toughest among the iterative pre-order and in-order traversal algorithm. The process of post order traversal remains same but the algorithm to achieve that effect is different. Since post-order traversal is a depth-first algorithm, you go deep before you go wide. The left subtree is visited first, followed by right subtree and finally the value of a node is printed. This is the reason why the value of root is printed last in the post-order traversal algorithm.
No doubt that Oracle's Java certification is one of the most valuable certification for IT industry and helps you to get a better job, a better pay, and a better rise in your current salary. It also improves your recognition and job prospects because many big clients demands certified Java programmers for their mission critical applications. Because of huge popularity and usefulness, many Java developers and computer science graduate aspire for Java certifications. I often receive queries like, what is the best way to prepare for Java certifications like OCAJP or OCPJP? or I am already coding in Java, do I need to prepare explicitly for this exam to do well or my Java development experience is enough? I have 5 years of experience in Java, do I need to prepare for OCAJP 8 or OCPJP 8 exam? etc.
In order to become a Java 8 Certified developer, you need to pass two exams, the OCAJP 8 exam with code 1Z0-808 and the OCPJP8 exam with code 1Z0-809. You will not be a Java SE 8 certified programmer if you just pass the OCAJP8 exam. In order to prepare for both these exams, you need to choose a good study guide and a good mock exam simulator, apart from writing programs on daily basis. Since there are a lot of demand for Java 8 certified professionals across the world, it seems to be a good opportunity to change your career path by learning Java 8, if you are doing some boring IT work and wants to become an application developer. The Java certifications will provide you both knowledge and competitive edge over other candidates who are applying for same Java developer job.
Every Programmer loves free eBook, even more, if it comes from renowned technical book publishers like Oreilly or Manning. In the last article, I have shared some of the best free Java programming books and today I am going to share some of the equally best free Python Programming books. These books are not illegal copies which are uploaded into the internet, but they are the legal copies, made free by their author and publishers. Though these are not full-fledged books but concise eBooks, they are very informative and comprehensive enough to learn things like Data Science and Functional programming in Python.