Declaring a two-dimensional array is very interesting in Java as the Java programming language provides many ways to declare a 2D array and each one of them has some special things to learn about. For example, It's possible to create a two-dimensional array in Java without specifying the second dimension, sounds crazy right? but it's possible because a two-dimensional array in Java is nothing but an array of array. You can even create a two-dimensional array where each subarray has a different length or different type, also known as a heterogeneous array in Java. This means it's possible to create a two-dimensional array with variable column length in Java. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

Sometimes, we need to merge multiple lists into one before performing any operation, say Iteration or transformation. It's quite common to merge two lists, or combine them into a bigger list and there are multiple ways to do it. In this article, we will take a look at two simple way to join two lists in Java, you can further extend that idea to join any number of List or it's implementation e.g. ArrayList or LinkedList in Java. One way to merge multiple lists is by using addAll() method of java.util.Collection class, which allows you to add the content of one List into another List. By using the addAll() method you can add contents from as many List as you want, it's the best way to combine multiple List. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

You will always see some interview questions from Exception and Error handling in core Java Interviews. Exception handling is an important aspect of Java application development and its key to writing robust, stable Java programs, which makes it natural favorites on interviews. Questions from Error and Exception in Java mostly based on the concept of Exception and Error in Java, How to handle Exception , best practices to follow during Exception handling etc. Though multithreading, garbage collection, JVM concepts and questions from object oriented design rules these interviews, you should always expect and prepare some questions on effective error handling. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

There are several ways to create an array in Java, for example, you can declare the array without initializing it, or you can create and initialize the array in the same line. If you want to make an array with values, then you need to first decide which type of array you want to create? e.g., do you want a String array, which can contain String objects like "abc," "def," or do you want to create an int array that contains int values like 10, 20, etc. In Java, you can create an array of any type, including primitives like byte, int, long, and objects like String, Integer, and other user-defined objects. Let's some code to make a new array in Java. --- Java Interview questions and tutorials

Hello guys, if you have been using Eclipse for Java development then you might have seen this dreaded  "Access restriction: The type BASE64Decoder is not accessible due to restriction Error" before. This error comes when you are trying to encode String into Base64 using BASE64Decoder in Eclipse because the class BASE64Decoder is not part of JDK's public API, it comes from sun.misc package which is non-public. Though this class is present in JDK and JRE and allows you to encode and decode String into base 64, any access to this class from Eclipse flags as an error in Eclipse IDE. If you compile and run the same program from the command line or NetBeans you will not get this error. --- Java Interview questions and tutorials

One of the most common programming task while working with date and time objects are calculating the difference between dates and finding a number of days, months, or years between two dates. You can use the Calendar class in Java to get days, months between two dates. The easiest way to calculate the difference between two dates is by calculating milliseconds between them by converting java.util.Date to milliseconds using the getTime() method. The catch is converting those milliseconds into Days, Months and Year is not tricky due to leap years, the different number of days in months, and daylight saving times. --- Java Interview questions and tutorials

What is the difference between TCP and UDP is a popular networking question from Java interviews? Though TCP or UDP is Java independent concept and very likely to be asked in other programming language interviews as well, many programmers do not really understand them clearly. They sure have heard them because TCP and UDP are two of the most important transport protocol of the internet, but when it comes to listing down the difference between them, they fail to mention key differences in terms of ordering, guaranteed delivery, speed, and usage.  --- Java Interview questions and tutorials

The Quicksort algorithm is one of the very popular sorting algorithms in programming, often used to sort a large array of numbers. Though there is numerous algorithm available to sort a list of objects, including integer, string, and floating-point number, quicksort is best for general purpose. It's a divide and conquers algorithm, where we divide the given array with respect to a particular element, known as 'pivot' such that the lower partition of the array is less than the pivot and upper partition elements of the array are higher than the pivot. --- Java Interview questions and tutorials

Hello guys, if you want to learn Java and look for the best Java courses online, you have come to the right place.  Earlier, I have shared the best Java Programming courses, and today, I am going to review Java Programming and Software Engineer Fundamentals course from Coursera. This is one of the top Java courses from Coursera, and more than 180K students have already joined this course. This course is offered by Duke University, and it also offers a certification after completing all modules of the course and doing the project on the final module. While the social proof is enough to join this course, we'll review this course on different parameters like Instructor quality, course structure, content, etc., to help you make an informed decision. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

You can convert a character like 'A' to its corresponding ASCII value 65 by just storing it into a numeric data type like byte, int, or long as shown below : int asciiOfA = (int) 'A'; Here casting is not necessary, simply assigning a character to an integer is enough to store the ASCII value of character into an int variable, but casting improves readability. Since ASCII is a 7-bit character encoding, you don't even need an integer variable to store ASCII values, byte data type in Java, which is 8 bits wide is enough to store the ASCII value of any character.  So you can also do like this : byte asciiOfB = 'B'; // assign 66 to variable --- Java, Unix, Tibco RV and FIX Protocol Tutorial

Almost all Java developers know that compiler adds a default constructor or better known as a no-argument constructor in every Java class, but many of them forget that it only does when you don't provide any other constructor. This means it becomes the developers' responsibility to add a no-argument constructor if he is adding an explicit constructor. Now, Why it's important to provide a default constructor in Java, What happens if your class doesn't have a no-argument constructor? Well, this is how it's asked in many Java interviews, most commonly as part of Spring and Hibernate interviews. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

Hello there, If you want to loop over an array in Java but not sure how to do that then you have come to the right place. Earlier, I have shared many Java array tutorials and the best Java courses for beginners, and today, I am going to teach you how to iterate over an array in Java. There are multiple ways to loop over an array in Java, like you can use a for loop, an enhanced for loop, a while loop, or a do-while loop. Since while and do-while needs a condition to terminate they often depend upon the content of the array like stop when the current element is null or even or odd etc. If you just want to iterate over an array to access each element like loop over an array and print each entry then you should use either for loop or the enhanced for loop. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

Apart from reading files, Scanner can also read user input from Console in Java. Just like in the case of reading files, we have provided File as a source for scanning, We need to provide System.in as a source to scan for user input in Console. Once you created and initialized java.util.Scanner, you can use its various read method to read input from users. If you want to read String, you can use nextLine(), if you want to read integer numbers, you can use nextInt().  --- Java Interview questions and tutorials

Can a static method be overridden in Java, or can you override and overload static method in Java, is a common Java interview questions mostly asked to 2 years experienced Java programmers. The answer is, No, you can not override static method in Java, though you can declare a method with the same signature in a subclass. It won't be overridden in the exact sense, instead, that is called method hiding. But at the same time, you can overload static methods in Java, there is nothing wrong with declaring static methods with the same name, but different arguments. Some time interviewer also ask, Why you can not override static methods in Java? The answer to this question lies in the time of resolution. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

Hello guys, In the last article, you have learned how to reverse an array in place in Java, and today I have come back with another array-based coding interview question. It's also one of the frequently asked coding questions, not as popular as the previous one but still has been asked a lot of times on various Programming Job interviews, particularly to beginners. In this problem, you are asked to write a program to remove a given number from the given array. It may seem easy, but the trick is that because an array is a fixed data structure and you cannot change the length of the array once created.  --- Java Interview questions and tutorials

10 EJB Interview Questions and Answer from my collection of interview questions. I have been sharing interview questions on various topics like Singleton interview questions, serialization interview questions, and most recently Spring interview questions. No doubt these questions are very important for performing better in J2EE and EJB interviews but also they open a new path for learning as you may find some concepts new even while revising your knowledge in EJB. EJB interviews have always been tough because its difficult to find people who have hands-on experience on Enterprise Java Beans (EJB) and most of the guys either have worked only on sample projects and are not aware of critical functionalities like distributed transaction management, container-managed persistence, and various other services which EJB provides. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

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. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

You can use a regular expression and replaceAll() method of java.lang.String class to remove all special characters from String. A special character is nothing but characters like - ! #, %, etc. Precisely, you need to define what is a special character for you. Once you define that you can use a regular expression to replace those characters with empty String, which is equivalent to removing all special characters from String. For example, suppose, your String contains some special characters e.g. "Awesome!!!" and you want to remove those !!! to reduce some excitement, you can use replaceAll("!", "") to get rid of all exclamation marks from String. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

One of the common Java coding interview questions is to write a program to reverse a String in place in Java, without using additional memory. You cannot use any library classes or methods like StringBuilder to solve this problem. This restriction is placed because StringBuilder and StringBuffer class define a reverse() method which can easily reverse the given String. Since the main objective of this question is to test the programming skill and coding logic of the candidate, there is no point in giving him the option to use the library method which can make this question trivial.  --- Java Interview questions and tutorials

valueOf Example in Java Enum valueOf method of Java Enum is used to retrieve Enum constant declared in Enum Type by passing String in other words valueOf method is used to convert String to Enum constants. In this Java Enum valueOf example we will see how to use the valueOf method in Java. valueOf method is implicitly available to all Java Enum because every enum in Java implicitly extends java.lang.Enum class. valueOf method of enum accepts exactly the same String which is used to declare Enum constant to return that Enum constant. valueOf method is case-sensitive and invalid String will result in IllegalArgumentException. --- Java Interview questions and tutorials

Hello guys, I have an interesting news to share with you today. After a long wait of almost 10 years, the Effective Java 3rd edition is finally coming this year, hopefully, December 2017. The Effective Java 2nd Edition was released in May 2008 and updated for Java SE 6, but it been, good 10 years now and there is a lot of interest from Java developers around the world for Effective Java 3rd edition after Java SE 8 release and I am very happy to inform you guys that, finally, all our wishes are granted and Effective Java 3rd edition is set to arrive this year. It will not only cover Java 9 release but also all the changes from Java 7 and Java 8. --- Java, Unix, Tibco RV and FIX Protocol Tutorial

Hello guys, if you have been doing Java development for few years, then you know that Performance is the key for any Java application. As a senior Java developer, one should know how to improve the performance of Java applications and understand memory management and garbage collection, which often causes Performance in Java applications. These are some advanced skills that take some effort to develop. It doesn't come by default even if you have been programming in Java for years, as most people don't touch these topics. Many of them are afraid or take the performance tuning work and always look up to the most senior or brilliant developers in their team. --- Java Interview questions and tutorials