How to set JAVA_HOME environment in Linux, Unix and Windows? Example

JAVA_HOME is a system environment variable that represents the JDK installation directory. When you install JDK in your machine (Windows, Linux, or UNIX) it creates a home directory and puts all its binary (bin), library(lib), and other tools. In order to compile the java program "javac" tool should be in your PATH and in order to get that in PATH we use the JAVA_HOME environment variable. Many tools like ANT and web servers like tomcat use JAVA_HOME to find java binaries. In this article, we will see how to set the JAVA_HOME environment variable in the different operating systems including Windows (Windows 7, Vista, XP) and Linux (Unix).

JSTL Set tag examples or <c:set> in JSP – Java J2EE Tutorial

JSTL set tag or <c:set> also called as JSTL Core tag library is a good replacement of <jsp:setProperty> jsp action which lacks lot of functionality and only allow you to set bean property. you can not set Map's key-value or create a scoped variable by using <jsp:setProperty>. jstl <set> tag allows you to do all the stuff related to setting or creating variables or attributes. by using JSTL <c:set> tag you can :

What is Constructor Overloading in Java? Example

Constructor overloading in java allows having more than one constructor inside one Class. in the last article we have discussed method overloading and overriding and constructor, overloading is not much different than method overloading. Just like in the case of method overloading you have multiple methods with the same name but different signatures, in Constructor overloading, you have multiple constructors with a different signature with the only difference that Constructor doesn't have a return type in Java. That constructor will be called as an overloaded constructor.

Why use Memory Mapped File or MapppedByteBuffer in Java? Example

Memory Mapped Files in Java is a rather new java concept for many programmers and developers, though it’s been there from JDK 1.4 along with java.nio package. Java IO has been considerably fast after the introduction of NIO and memory-mapped file offers the fastest IO operation possible in Java, that's the main reason of Why high-performance Java application should use Memory Mapped files for persisting data. It's already quite popular in the high-frequency trading space, where the electronic trading system needs to be super fast and one-way latency to exchange has to be on the sub-microsecond level.

How to Fix Tibrv Errors and Exceptions? Examples

While working with tibco rv for many years I found that Tibco errors are mysteriously difficult to diagnose for a newcomer and minor differences between syntax and semantics along with network specifics lead to some strange errors. here I am putting the most common error which I have faced mainly because of some silly mistake in syntax and spent hours to figure out the exact cause during my initial days. This list is by no means complete and I would encourage to put any other error you have encountered to make this list more useful. Any suggestions, input feedback always welcome.

How to add Primary key into a New or Existing Table in SQL Server? Example

Since a primary key is nothing but a constraint, you can use the ALTER clause of SQL to add a primary key into the existing table. Though it's an SQL and database best practice to always have a primary key in a table, you will often find tables that don't have a primary key. Sometimes, this is due to lack of a column that is both NOT NULL and UNIQUE (constraint require to be a primary key), but other times purely due to lack of knowledge or lack of energy. If you don't have a column that can serve as the primary key, you can use identity columns for that purpose. Alternatively, you can also combine multiple columns to create composite primary keys, like you can combine firstname and lastname to create a primary key name, etc.

Difference between Session Level Reject and Business message Reject in FIX Protocol? Answer

FIX Protocol tutorials: Difference between Session Level Reject and Business message Reject
In FIX protocol there are multiple ways of rejecting message some of them are using an Execution Report (MsgType=8) and ExecType=8 to reject a FIX message if it can not be acceptable by exchange e.g. Sending order for an exchange and link between broker and exchange is down. Another way of rejecting message is OrderCancelReject (FIX MsgType=9) which is used to reject amend (OrderCancelReplace message FIX MsgType 35=G) and cancel (OrderCancelRequest FIX MsgType=F) messages if its not possible to modify or cancel original message e.g. Sending Cancel request to an already filled order will be rejected by OrderCancelReject message in FIX protocol.

Why non-static variable cannot be referenced from a static context? Example

"non-static variable cannot be referenced from a static context" is the biggest nemesis of someone who has just started programming and that too in Java. Since the main method in java is the most popular method among all beginners and they try to put program code there they face "non-static variable cannot be referenced from a static context" compiler error when they try to access a non-static member variable inside the main in Java which is static. if you want to know why the main is declared static in Java see the link.

Top 5 Java Forums for Programmers and Developers

When you face a Java problem where do you go? StackOverflow, Coderanch, or Official Java forums? Yes, there are lots of online resources to help a Java programmer when he is stuck. Being one of the most popular programming languages ever, Java has a huge community. There are lots of blogs, websites, and forums to help you with the minute detail of Java programming. It doesn't matter if you are a beginner facing a problem or an expert looking for the best possible way to do certain things in Java, forums always provide good support.

How to find if JVM is 32 or 64 bit from Java program? Example

You can find JVM bit sizes like 32 bit or 64 bit by using either running java command from the command prompt or by using System.getProperty() from Java program. The question is why do you want to know hardware or platform configuration while writing Java code which is supposed to write once and read anywhere(32 bit, 64 bit, etc)? Yes we don't really need to know whether JVM is 32 bit or 64 bit more often but there are many situations when this matters

Java Best Practices for Method Overloading? Examples

You need to be careful while overloading a method in Java, especially after the introduction of autoboxing in Java 5. Poorly overloaded method not only adds confusion among developers who use that but also they are error-prone and leaves your program at compiler's mercy to select proper method. One of the best examples of a poorly overloaded method is the removal method of ArrayList. There are two versions of remove, first, one which takes an Object as argument i.e. remove(Object element), and the second one, which takes an index as argument i.e. remove(int index).

How to take array input from command line in Java ? Scanner Example

There is no direct way to take array input in Java using Scanner or any other utility, but it's pretty easy to achieve the same by using standard Scanner methods and asking some questions to the user. For example, if you want to take a one-dimensional array of String as input then you can first ask the user about the length of the array and then you can use a for loop to retrieve that many elements from the user and store them in an array. You can use the next() to take a String input from the user. Similarly, if you need to take an integer array or double array, you can use the nextInt() or nextDouble() method of the Scanner class.

Top 10 FIX Message Interview Questions Answers for Beginners

FIX (financial information exchange) protocol is the global protocol used for Electronic trading of different asset classes e.g Equity, Fixed Income FX (foreign exchange) , Derivatives Futures and Options and its knowledge is essential to understand Electronic trading and FIX messages. I have listed some of the very common but informative questions asked in FIX protocol interview question, this list is by no means complete and only contains questions on top of my mind, I would encourage reader to post any question they have been asked and I will include on this list.

How to view FIX Messages in a Readable format? Free Online FIX Message Viewer Tool

It's been a long time, I wrote anything related to FIX protocol, my last article was about FIX protocol dictionaries, also known as Fixionnary, one of the most important tools of the trade for Java developers and support personnel working in FIX. Today, I am going to share another useful tool called FIX Log Viewer, which allows you to view FIX engine logs in a much more readable format.

How to use String.codepoint() method in Java? Example Tutorial

CodePoint method in String is used to get Unicode code point value at index or before the index.  In String class we have a lot of utility methods for dealing with String like Split, replace, and SubString method but here I am discussing a relatively lesser-known method codePointAt(), codePointCount(), and codePointBefore(), but before going deep about this method lets first understand what is of the code point, what exactly CodePoint method does and how to use CodePointAt, CodePointBefore methods using java code example.