10 Examples of using ArrayList in Java - Tutorial

ArrayList in Java is most frequently used collection class after HashMap in Java. Java ArrayList represents an automatic re-sizeable array and used in place of array. Since we can not modify size of an array after creating it, we prefer to use ArrayList in Java which re-size itself automatically once it gets full. ArrayList in Java implements List interface and allow null. Java ArrayList also maintains insertion order of elements and allows duplicates opposite to any Set implementation which doesn't allow duplicates. ArrayList supports both Iterator and ListIterator for iteration but it’s recommended to use ListIterator as it allows the programmer to traverse the list in either direction, modify the list during iteration, and obtain the Iterator's current position in the list. But while using ListIterator you need to be little careful because ListIterator has no current element; its cursor position always lies between the element that would be returned by a call to previous() and the element that would be returned by a call to next(). In this Java ArrayList tutorial we will see how to create Java ArrayList and perform various operations on Java ArrayList. This collection class is also favourites on many core Java interviews with questions like Difference between ArrayList and Vector  or LinkedList vs ArrayList.

Why wait notify and notifyAll called from synchronized block or method in Java

Why wait (), notify () and notifyAll () must be called from synchronized block or method in Java

Why wait(), notify() and notifyAll() method must be called from synchronized block or method in JavaMost of Java developer knows that wait() ,notify() and notifyAll() method of object class must have to be called inside synchronized method or synchronized block in Java but how many times we thought why ? Recently this questions was asked to in Java interview to one of my friend, he pondered for a moment and replied that if we don't call wait () or notify () method from synchronized context we will receive IllegalMonitorStateException in java. He was right in terms of behavior of language but as per him interviewer was not completely satisfied with the answer and wanted to explain more about it. After the interview he discussed the same questions with me and I thought he might have told about race condition between wait () and notify () in Java that could exists if we don't call them inside synchronized method or block. Let’s see how it could happen:

Top 30 UNIX command Interview Questions asked in Investment Banks

UNIX Interview Questions and Answers
UNIX or Linux operating system has become default Server operating system and for whichever programming job you give interview you find some UNIX command interview questions there. These UNIX command interview questions are mostly asked during Java development and Support role interviews on various investment banks mostly because most of electronic trading systems or stock trading system works on Unix servers. As we know that high volume low latency systems which wants to take advantage of little bit of volatility in market for Equity , Futures and options or Foreign exchange trading need a stable server side operating system and Redhat Linux is doing great job there. with the advent of Algorithmic trading this speed factor becomes more important so getting someone who has good knowledge of operating system and commands on which these trading system runs is definitely required. but these UNIX command interview questions are equally applicable for any job interview which requires some work on Unix Operating System. With the growing use of Linux in form of RedHat, Solaris and IBM AIX its must to keep you familiar with essential Linux commands available on various platforms. 

10 points about Java Heap Space or Java Heap Memory

10 Points about Java heap memory
When I started java programming I didn't know what is java heap or heap space in Java, I was even not aware of where does object in Java gets created, it’s when I started doing professional programming I came across error java.lang.OutOfMemoryError in Tomcat then I realized What is Heap in Java or Java Heap Space. Its happens with most of programmer because learning language is easy but learning basics is difficult since there is no formal process which can teach you every basics of programming its experience and work which reveals the secret of programming. For Java developer knowledge of Heap in Java, setting size of java heap space, dealing with Java heap space OutOfMemoryError, analyzing heap dumps is very important. This Java Heap tutorial is for my beginner brothers who are new in programming and learning it. It makes too much difference if you know the basics and underlying, until you know that object is created in heap, you won't be able to think why OutOfMemoryError occurs in Heap. I am trying to provide as much information about Heap in Java as I know but would like you guys to contribute and share your knowledge about Heap in Java to benefit all. By the way if you are confused between heap and stack, which is where your local variables get created, then, you can also check difference between heap and stack memory in Java.

Tibco Tutorials for beginners

This Tibco Tutorial is collection of all my previous Tibco rendezvous and Tibco EMS tutorials. I have written this compilation post to provide all tibco tutorials at one place for easy navigation and access. Anyone who is started working on Tibco on any investment bank or brokerage house for there electronic trading systems or algorithmic trading system can benefit from these tibco tutorials because these are based on my experience in stock trading systems which uses Tibco Rendezvous for all there Front-End backend communication. Tibco Certified messaging is used by Electronic trading system or Order Management system to receive orders and Send Execution in FIX Protocol.

Top 10 Tips on Logging in Java - Tutorial

Java logging or logging in java is as much an art as science. knowing write tools and API for java logging is definitely science part but choosing format of java logs , format of messages, what to log in java , which logging level to use for which kind of messages are purely an experienced based things and sort of art which you learn by applying logging in java. Since its proven fact that java logging severely affects performance and I have seen latency of online stock trading application goes multiple times if they run in DEBUG mode than in WARN or higher level mode. Since latency and speed is major concern for any electronic trading system or high volume low latency stock trading system, it becomes absolutely necessary to understand and learn java logging in great details and best practices and tips available on logging in java. This is not just for finance and investment banking domain but also to any java server or client application which requires speed and java logging at same time.