Top 75 Programming Interview Questions Answers to Crack Any Coding Job Interview

Hello guys, if you are preparing for your next Programming Job interview and looking for some frequently asked Coding or Programming questions to practice then you have come to the right place. In this article, I am going to share some of the most commonly asked Coding questions from Programming Job interviews. In order to do well on the Coding interview you need practice, you just can't go there and try to solve the coding problems in limited time, that's actually one of the most common reasons to fail your programming Job interviews.  Sometimes, the interviewer also asks a little bit easier coding questions on a telephonic interview like revering array in place or reversing a string in place.

10 Examples of an Array in Java

Along with the String, the array is the most used data structure in Java. In fact, String is also backed by a character array in Java and other programming languages. It's very important for a Java programmer to have good knowledge of array and how to do common things with array e.g. initialization, searching, sorting, printing array in a meaningful way, comparing array, converting an array to String or ArrayList and doing some advanced slicing and dicing operation with an array in Java. Like my previous tutorials 10 examples of HashMap in Java, I'll show you some practical examples of an array in Java. If you think, any important operation is not included, you can suggest their examples and I'll add them to this list.

How to implement linked list data structure in Java using Generics

The linked list is a popular data structure for writing programs and lots of questions from a linked list are asked in various Programming Job interviews. Though Java API or JDK provides a sound implementation of the linked list data structure as java.util.LinkedList, a doubly-linked list, you don't really need to implement a linked list of your own for writing production code, but all these interview questions require you to code a linked list in Java for solving coding problems. If you are not comfortable creating your own a linked list, it would be really difficult to solve questions like reversing a linked list or finding the middle element of a linked list in one pass.

Top 40 Binary Tree Coding Interview Questions for Programmers

A lot of programmers and my readers have been asking me to share some binary tree-based coding interview questions, just like I have done for the array, linked list, string, software design, patterns, hash table, and data structure in general. This task was actually pending for quite some time and it was stuck for me trying to find the solution for each and every question I could have collected. So, I decided to publish the list of binary tree interview questions now and possibly publish the solution as a separate article later. This is like creating an interface and providing implementation later so that you don't block other people who are dependent upon your interface (actually, this is one advantage of using the interface in Java or any other programming language).

Post order traversal Algorithms for Binary Tree in Java with example

In the last couple of articles, you have learned about pre-order and in-order tree traversal algorithms in Java, and today, you will learn about the post order traversal in a binary tree. It is the toughest of all three tree traversal algorithms and programmers generally struggle to implement this when asked in a coding interview, hence it makes sense to understand and practice this algorithm before going for the interview. The post order traversal is also a depth-first algorithm because you go deep before you visit other nodes on the same level.

What Every Java Programmer should know about Array Data Structure

Without any doubt, the array is one of the most used data structure in all programming languages, including Java. Pick up any programming language be it functional, object-oriented, imperative or even scripting languages like Python, Bash, and Perl, you will always find array. That's why it's important for any programmer to have a good understanding of the array data structure. Like any other data structure, the array also provides a way to organize and store objects, but the way it does makes all the difference. An array is used to store elements in the contiguous memory location and many C, C++ programmers can take advantage of a pointer to work with an array.

How to print all leaf nodes of a Binary Tree in Java without Recursion

In the last article, you have learned how to print all leaf nodes of a binary tree in Java by using Recursion, a useful technique to solve binary tree problems and in this article, we'll answer the same question without using Recursion. Why should we do this? Well, it's a typical pattern on a programming job interview to solve the same problem using both Recursion and Iteration. Since some questions are easy to solve using recursion like linked list problems, binary tree-based problems, tower of Hanoi, or Fibonacci series but their non-recursive solution is comparatively tricky, interviewer test candidates against this shift in the algorithm.

10 Books Java Developers Should Read in 2021

Hello guys, If you are a Java developer and wondering what to read in 2021, then you have come to the right place. In this article, I am going to share 10 books on Java, Spring, and related technology a Java developer can read. I have included books for both experienced Java developer who is more inclined to learn about architecture stuff,  developing for Cloud, MicroService, Java 9 to Java 13 features, and Spring 5 features and thinking of learning Kotlin to improve their productivity. Still, I have not forgotten junior and less experienced Java developers or some who are thinking of starting their journey into the Java world in 2021.

3 Ways to change Embedded Tomcat Server Port in Spring Boot Application

If you know Spring Boot really simplifies the Java web development by embedding essential libraries as well as a tomcat server to run Java web application. By default, this tomcat server listens on port 4588, and for any reason, if you want to change, then Spring boot provides several configuration options to achieve that. For example, I wanted tomcat to listen on port 8080 because port 80 is forwarded to 8080 in our Linux machine, and we wanted our clients to provide our client with a clean URL without a port.

Difference between @SpringBootApplication vs @EnableAutoConfiguration annotations in Spring Boot

Even though both @SpringBootApplication and @EnableAutoConfiguration can be used to enable the auto-configuration feature of Spring Boot, there is a subtle difference between them. The @SpringBootApplication does much more than what @EnableAutoConfiguration does. It's actually a combination of three annotations: @Configuration, which is used in Java-based configuration on Spring framework, @ComponentScan to enable component scanning of components you write like @Controller classes, and @EnableAutoConfgiuration itself, which is used to allow for auto-configuration in Spring Boot application.

How to Print all leaf Nodes of a Binary tree in Java - Coding Interview Questions

This is another interesting coding problem which is based on a binary tree and mostly asked beginner programmers. If you have some experience in solving binary tree-based problems then it's rather easy to solve because, like many other binary tree algorithms, you can use recursion to print all leaf nodes of a binary tree in Java. Since the tree is a recursive data structure, you can apply the same algorithm to both the left and right subtree. In order to solve this problem, the first thing you should know is what is a leaf node because if you don't know that then you won't be able to solve the problem. Well, a leaf node is the one who's left and right child nodes are null.

Counting Sort in Java - Example

Hello guys, the Counting sort algorithm, like Radix sort and Bucket sort, is an integer-based algorithm (i.e. the values of the input array are assumed to be integers), non-comparison, and linear sorting algorithm. Hence counting sort is among the fastest sorting algorithms around, in theory. It is also one of the few linear sorting algorithms or O(n) sorting algorithm. It's quite common in Java interviews nowadays to ask, whether do you know any O(n) sorting algorithm or not. If you face this question in the future, you can mention Radix sort, Bucket sort, or Counting sort algorithms.

What is the use of ContextLoaderListener in Spring MVC Framework?

The ContextLoaderListner is one of the essential components of the Spring MVC framework, probably the most important after the DispatcherServlet itself. It is used to create the root context and responsible for loading beans, which are shared by multiple DispatcherServlet like beans related to the service layer and data access layer. In general, When you develop Spring MVC based web application and also using Spring in the services layer, you need to provide two application-contexts. The first one is configured using ContextLoaderListener, and the other is set using DispatcherServlet. The DispatcherServlet is responsible for loading web component-specific beans like controllers, view resolvers, and handler mappings while, as I said before, ContextLoaderListener is accountable for loading middle-tier and data-tier beans which forms the back end of Spring applications.

Top 5 Data Science and Machine Learning degrees you can earn Online - Best of Lot

Hello guys, I have been sharing some online degree programs you can take online from last a couple of weeks as more and more people are looking for online technical degree programs. Earlier, I have shared Top 5 Computer Science degree you can earn online, and today, I will share the top 5 Data Science and Machine learning degrees you can earn online from the world's reputed universities.  Data Science is the way or the process of extracting insights and useful information from your data to understand different things and turn that data into a story in the shape of graphs and a dashboard that anyone can understand and by using many different programming languages like Python and R. But imagine if you can earn an online degree in this topic, that's what we are covering in this article.

4 Books to learn Java Programming from Scratch in 2021 - Best of lot

I receive half a dozen emails every day asking about which is the best to learn Java from scratch? Which book should I read in 2021 to learn Java? Or Which is the best Java for beginners? When I receive such an email, before giving my recommendation, I ask two questions, first do you have any programming experience? like, Are you coming from C, C++, or Python background? Or you are a fresher with no experience in programming, just a couple of classes on data structure and algorithm and operating system in college.

Top 21 Java HashMap Interview Questions and Answers

The java.util.HashMap is one of the workhorses of JDK. Along with ArrayList, it is one of the most used classes from Java's collection framework. There is hardly a real-world Java project, where I haven't seen the use of HashMap. It is an implementation of hash table data structure, and it's not a surprise that HashMap is so useful, as someone has rightly said, "if you could have just one data structure, make it a hash table". The hash table data structure allows you to search for a value in O(1) time if you have key. In Java, several implementations of hash table data structure exist like Hashtable, ConcurrentHashMap, LinkedHashMap, etc. but HashMap is your general-purpose map.

How to prepare Oracle Certified Master Java EE Enterprise Architect (1z0-807, 1Z0-865, 1Z0-866) - OCMJEA6 Exam

The OCMJEA 6 certification is one of the most difficult, time-consuming, and tiresome Java certifications. Still, it was also the one that made me learn and grow professionally. This certification consists of 5 phases:

Phase 1: Compulsory Course

At this point, the candidate is required to take at least one official Oracle course from Java at any partner company. You can complete this course during certification - before, during, or after.

If you already have experience in Java and architecture, leave to take the course at the end. If not, use the classes to gain knowledge for the test by doing them before. There is a complete grid of Java courses for the candidate to acquire the necessary know-how for this certification.

Top 25 Java Date, Time, and Calendar Interview Questions Answers

The Date and Time API is a very important one for day to day Java development work but many interviewers don't ask enough questions on this topic. Most of the questions are based on either Java Collection framework like  HashMap, ConcurrentHashMap, or ArrayList or on multi-threading concepts like volatile, synchronized, and atomic variables. This is not good and I think many interviewers have realized that a good understanding of date and time API is also important for a good Java developer. That's the main reason for an increasing number of date, time, and calendar-based Java interview questions in recent times, particularly in the last couple of years.

Top 5 Books to learn SQL and Database design in 2021 - Best of Lot

The SQL (Structured Query Language) is one of the most essential skills of a programmer. I would rate this skill similar to UNIX if you are a professional programmer because it doesn't matter whether you are Java, C++, or a .NET developer, you are bound to write SQL queries. Since a database is an integral part of any modern Java or Web application, the Interviewer always preferred candidates with excellent SQL skills. Now, the big question comes, how a programmer can learn SQL? Does just knowing how to query a table is enough? If you remember, insert, update, delete, and select, then are you a competent SQL programmer?

Solving org.springframework.beans.factory.BeanCreationException: Error creating bean with name X [Java Spring]

If you are using the Spring framework in your Java application and getting this error during startup it means Spring is not able to initialize the bean X and add into its application context, Why? There could be multiple reasons like a typo on the spring bean name. Let's take a closer look at the stack trace to find out the real reason:

BeanInstantiationException: Could not instantiate bean class [X]: No default constructor found; nested exception is java.lang.NoSuchMethodException: X.()

Here X is the class, which is declared as Spring bean. The error clearly says that the default constructor is not present in class X.