Java HashMap is not a thread-safe implementation of key-value storage, it doesn’t guarantee an order of keys as well. In the scope of this article, I’ll explain: HashMap internal implementation methods and functions and its performance (O(n) time complexity) collisions in HashMap interview questions and best practices Keep reading and use a table of contents … Read more
Java Object toString method is one of the basics in Java. toString function returns a string representation of an object. I’ll explain how to add toString method to a Java class with code examples. Using toString in Java To string method in Java should be informative to make it easy to read. it’s recommended to … Read more
The basic “for” loop was enhanced in Java 5 and got a name “for each loop”. It also called: Java for each loop, for in loop, advanced loop, enhanced loop. It’s more readable and reduces a chance to get a bug in your loop. You can use for each loop in Java to iterate through … Read more
I hope you already heard about string constant pool in Java? If no, I’ll explain what is it. The main advantage of the string pool in Java is to reduce memory usage. When you create a string literal: Java checks for the same value in the string pool. If it’s present, Java takes a reference … Read more
This article is an overview of Java JSON libraries. You’ll learn how to parse (decode) JSON in Java – string to object representation. I’ll explain 2 approaches of parsing JSON in Java and what is a best Java JSON library for each case. But first of all, let’s define what is a JSON and why … Read more
There are 2 interfaces for sorting in Java: Comparator and Comparable. I’ll explain to you how to define Comparator and Comparable objects, what’s the difference and when you can use it. Let’s comparable vs comparator fight begin… When to Use Comparable and Comparator So what is the main difference between Comparator and Comparable interfaces? Comparator … Read more
List is an interface for an ordered collection of elements in Java. You can easily add, remove and get elements by index. 2 main things that you should keep in mind using Lists in Java: Lists guarantee an order of elements. That means if you will add 1, 2, 3 integers to the list, you … Read more
Java static methods are one of the most important language instrument. I’ll explain what’s static function in Java, how to make it and what is its purpose. I’ll describe what is the difference between static and non-static methods and why main() method in Java is static. To define static method you should add “static” keyword … Read more
Java Thread is a basic of a multithreading program. This article is the first part of Java concurrency topics. I’ll give answers to the following interview questions: How to create a thread in Java? What is a Thread Lifecycle? How to prioritize thread execution? How to stop a thread in Java? What is a daemon … Read more
So what is an abstraction in OOP programming? Let’s imagine you have a car. it has a lot of characteristics like a weight, dimensions, color, maximum speed etc. To describe a Car object you need only color and max speed for your use-case. Weight and dimensions don’t matter to you. Abstraction means showing only necessary … Read more