Prashant Sharma Official

Java Collections Deep Dive (Simple & Complete Guide) Introduction In real Java applications, we rarely work with just one value. Most of the time, we deal with: A list of users A set of permissions A map of IDs and objects A queue of tasks Handling such data using normal variables is not possible. This is where  Java Collections  come into the picture. Java Collections are ready-made data structures provided by Java to store, manage, and process multiple objects easily and efficiently. Understanding Java Collections is extremely important for: Backend development Real-world applications Java interviews Why Java Collections Are Needed Before Java Collections, developers used  arrays . Arrays have multiple problems: Fixed size (cannot grow or shrink) No built-in methods for sorting or searching Difficult to manage large and dynamic data Java Collections solve all these problems: Dynamic size Easy add, remove, and update Built-in algorithms Cleaner and readable code Java...

Java HashMap Internals Explained in Simple Terms (With Examples & Time Complexity) Java  HashMap  is one of the most frequently asked topics in Java interviews. Many developers use it daily, but very few understand  how it actually works internally . In this article, we will explain: What HashMap is How HashMap stores data internally Role of  hashCode()  and  equals() What collisions are and how they are handled Improvements made in newer Java versions Time complexity of all major operations How to reduce frequent collisions All explanations are in  simple terms , with  examples . 1. What Is a HashMap? A  HashMap  stores data in  key–value pairs . Example: Map<String, Integer> map = new HashMap<>(); map.put("A", 10); map.put("B", 20); Key characteristics: Keys must be  unique Values can be duplicated Order is  not guaranteed One  null key  is allowed Multiple null values are allowed Why HashMap is...

Why HashMap Uses  (n - 1) & hash  and Why Capacity Is Always Power of 2 If you are learning  Java HashMap internals , one line that often confuses beginners is: index = (n - 1) & hash; Many people ask: Where is the  power of 2  here? Why not use  %  (modulo)? Why does HashMap care so much about powers of 2? In this article, we’ll explain everything in  very simple terms . What Is  n  in  (n - 1) & hash ? In this formula: index = (n - 1) & hash; n  is the  capacity of the HashMap , meaning the  number of buckets . Important rule: HashMap capacity is ALWAYS a power of 2 Examples: 16 → 2⁴ 32 → 2⁵ 64 → 2⁶ 128 → 2⁷ So the  power of 2 is hidden inside  n . Why HashMap Capacity Must Be Power of 2 HashMap calculates bucket index using  bitwise AND ( & ) , not modulo ( % ). This works correctly  only when  n  is a power of 2 . Let’s understand this with an example. Example: Cap...

Top Backend Anti-Patterns That Kill Scalability Scalability issues usually do not appear on day one. Most backend systems work perfectly fine with low traffic. The problems start  when users increase and data grows . In many cases, the system fails not because of traffic, but because of  bad backend design decisions made early . These decisions are called  anti-patterns . In this article, we will cover the  most common backend anti-patterns  that silently break scalability, explained in simple language with clear reasoning. 1. Turning Microservices Into a Distributed Monolith What Goes Wrong Teams break a monolithic application into multiple services and call it “microservices”. However: All services share the same database Services cannot be deployed independently One service failure affects others This is not real microservices. It is a  distributed monolith . Why This Hurts Scalability You cannot scale one service independently Database becomes a single ...

  Backend Developer Skills That Will Be Irrelevant by 2027 Over the next ~18 months (through the end of 2027) several task-level and tooling-centric skills that many backend developers treat as core will decline sharply in relevance. This post identifies those skills, explains why they will become less valuable, presents quantitative evidence and market forecasts, and finishes with actionable recommendations for developers who want to stay valuable. Short list of skills likely to become largely irrelevant (for most roles) by 2027: Writing boilerplate CRUD endpoints and scaffolding by hand Manual database provisioning/tuning for common operational loads (regular DBA chores) Hand-written deployment scripts and ad-hoc CI glue code for mainstream cloud stacks Handcrafting Kubernetes & YAML for routine deployments (the lowest-value parts) Handwriting repetitive SQL migrations and schema-change plumbing without automation Implementing standard authentication plumbing from scratch ...

Role of IP Addresses in System Design and Architecture When people start learning  system design , IP addresses often feel confusing or too technical. But in reality, IP addresses are  one of the simplest and most important ideas  behind how systems work. If you understand IP addresses properly, many things suddenly become clear: How websites work Why databases are not exposed to the internet How systems scale safely Let’s break this down  slowly and simply . What Is an IP Address? An  IP address  is a  number that identifies a device on a network . Every device connected to a network needs one: Mobile phone Laptop Server Database Think of an IP address like a  home address . If someone wants to send you a letter, they need your home address If one computer wants to send data to another, it needs the  IP address Example: 192.168.1.10 This number tells the network: “Send data to this exact device.” Without IP addresses, computers would not kno...