Top 10 Object-Oriented (OOP) Design Principles Java Programmers Should Know

The Object-Oriented Design Principles are the core of OOP programming, but I have seen most of the Java programmers chasing design patterns like Singleton pattern, Decorator pattern, or Observer pattern, and not putting enough attention on learning Object-oriented analysis and design. It's essential to learn the basics of Object-oriented programming like Abstraction, Encapsulation, Polymorphism, and Inheritance. But, at the same time, it's equally important to know object-oriented design principles. They will help you to create a clean and modular design, which would be easy to test, debug, and maintain in the future.

How to Print Duplicates from a Given String in Java? [Solved]

Problem : You have given an input String, write a program to print all the duplicates from input String. For example if given String is "Java" then your pogrom should print "a", and if given String is "C++" then your program should print "+". If String doesn't contain any duplicate then it should print nothing e.g. if you pass "Python" or "Ruby", it should print nothing. 

How to find the largest and smallest number in given Array in Java? Example Tutorial

Hello guys, today I am going to discuss one of the frequently asked programming interview questions to find the largest and smallest number from an integer array. This question is commonly asked on telephonic interviews and the first round for screening candidates. This coding problem is in the same league of other frequently asked algorithmic questions like Fibonacci, Palindrome, Prime, and Power of two checks. They are easy but you will find them difficult during the interview because of the pressure, particularly if you have not solved them before. Sometimes even if you have solved the problem one time, you tend to do mistakes because you haven't understood them properly. So, always take your time to understand the question.

Top 20 Amazon and Google Programming Interview Questions for Software Developers

Hello, In this article I am going to sharing some frequently asked programming job interviews from technical giants and startups. If you are going for a programming job interview with Microsoft, Google, or Amazon, you better be prepared for all kinds of questions. These companies are known to ask tough questions, tricky puzzles, and lots of data structure and algorithm questions. Since it's hard to prepare all these in a short time, it makes sense to at least have a good idea of frequently asked programming questions in Microsoft, Google, or Amazon.

Polymorphism and Inheritance Example in Java

Hello guys, If you are new to Java or Object oriented programming and wondering what is Polymorphism and Inheritance and what are their use then you have come to the right place. Polymorphism and Inheritance are two fundamental concepts in object-oriented programming that allow for flexibility and reusability of code. In Java, these concepts are closely related and often go hand in hand. Java Programming provides a couple of way to implement Inheritance like extending a class or implementing an interface. Similarly they provide overloading and overriding for Polymorphism. In the past, I have shared 40 object oriented questions as well as 23 design patterns and In this article, we'll explore these concepts with a practical example.

How to fix java.lang.NoSuchMethodError: main Exception in thread "main" in Java? Example

How to solve java.lang.NoSuchMethodError: main Exception in thread "main"

java.lang.NoSucMethodError comes when Java code tries to call a method that does not exist on a class, this could be either static or non-static method. a most common manifestation of java.lang.NoSuchMethodError is running a class that doesn't have the main method in Java. In this article, we will see what is "java.lang.NoSuchMethodError: main Exception in thread "main"", Why does java.lang.NoSuchMethodError comes and how to solve java.lang.NoSuchMethodError in Java.

How to deal with NullPointerException in Java with Examples - java.lang.NullPointerException Guide

The java.lang.NullPointerException or NullPointerException in Java is probably the first error or exception you will face in Java. It is a true nightmare for beginners in Java but pretty easy to solve once you get familiar with Exception handling in Java. What makes NullPointerException a little bit tricky to solve is its name which has a pointer in itself and Java does not support pointers like C++ or C, just like you don't have multiple inheritances in Java. As a Java developer with 20 years of experience, I have solved countless amount of NullPointerException and now I have developed a coding and debugging sense through which I can spot what causing a particular NullPointerException and how to fix it. 

Difference between transient and volatile keyword in Java? example

Surprisingly "Difference between transient and volatile keyword in Java" has asked many times on various java interviews. volatile and transient are two completely different keywords from different areas of Java programming language. the transient keyword is used during serialization of Java object while volatile is related to the visibility of variables modified by multiple threads during concurrent programming. The only similarity between volatile and transient is that they are less used or uncommon keywords and not as popular as public, static, or final.

Why wait, notify, and notifyAll methods are called from synchronized block or method in Java?

Most of the Java developers know that wait(), notify(), and notifyAll() methods 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 question 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 the behavior of language but as per him, the interviewer was not completely satisfied with the answer and wanted to explain to him more about it.

The multi-part identifier XXX could not be bound in SQL SERVER [Solution]

Problem, I was doing join statement and getting this error Msg 4104, Level 16, State 1, Line 69

The multi-part identifier "a.X" could not be bound."

Cause:

I was mixing implicit joins with explicit joins. That is allowed, but you need to be aware of how to do that properly.

The thing is, explicit joins (the ones that are implemented using the JOIN keyword) take precedence over implicit ones (the 'comma' joins, where the join condition is specified in the WHERE clause).

Difference between Wait and Sleep, Yield in Java? Example

The difference between wait and sleep or the difference between sleep and yield in Java is one of the popular core Java interview questions and asked on multi-threading interviews. Out of three methods that can be used to pause a thread in Java, sleep() and yield() methods are defined in thread class while wait() is defined in the Object class, which is another interview question. The key difference between wait() and sleep() is that the former is used for inter-thread communication while later is used to introduced to pause the current thread for a short duration. 

Difference between Thread vs Runnable interface in Java

Thread vs Runnable in Java is always been a confusing decision not just for beginners in Java but also for developers who have done a couple of projects in Java. Thread in Java seems easy in comparison to Runnable because you just deal with one class java.lang.Thread while in case of using Runnable to implement Thread you need to deal with both Thread and Runnable two classes. though the decision of using Runnable or Thread should be taken considering differences between Runnable and Thread and the pros and cons of both approaches.

What are AtomicInteger and AtomicLong in Java? How it works? compareAndSet() Example Tutorial

Concurrency is a fundamental aspect of modern software development, and Java provides a variety of tools and classes to help developers manage shared resources and coordinate the behavior of multiple threads. Among these tools one is atomic variables, which ensure that certain operations on shared data are performed atomically, I mean in one shot, without the need for explicit synchronization. In the past I talked about difference between atomic, synchronized, and volatile in Java and In this article, we'll explore atomic variables in Java, with a focus on AtomicInteger and AtomicLong, and explain how they work and how to use them effectively in Java. 

6 ways to get the selected text from html drop down list in jQuery?

One of the common task in web development is retrieving the selected text from a drop down list, which is nothing but HTML select element. This allows users to choose one of the options presented, each text is enclosed in option tag. how can we retrieve the selected text using jQuery? Well, there are multiple ways but core is first find the select element than the selected option by using :selected pseudo class selector.