Explaining OOP Concepts with a Supermarket Example

I’ve started writing to improve how I understand and explain concepts. My first blog focuses on a fundamental topic in programming—recursion vs iteration—and how they represent two different ways of thinking while solving problems. This is just the beginning. I’ll be writing on a mix of technical topics and general ideas going forward. Read here: https://lnkd.in/gw98ph77 #Programming #Learning #Algorithms #StudentJourney

Day 23 | Programming Classes at TAP Academy 🚨 Mastering String Problems: Logic Over Syntax You’re given a string: 👉 "he#l@lo123" Task? Remove only special characters. Sounds basic But this is where logic—not syntax—gets tested. 💥 The Real Trap Most of us write: if (ch >= 'a' && ch <= 'z' || ch >= 'A' && ch <= 'Z') { result += ch; } Looks correct. But this removes numbers too ❌ 👉 Problem: remove only special characters 👉 Your code: removes everything except alphabets That’s not solving. That’s assuming. 🧠 Core Concept Every character falls into 3 buckets: Alphabet Numeric Special character So don’t try to detect special characters (it’s messy across Unicode ❌) 👉 Instead, keep what you know is valid if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9')) { result += ch; } 🔍 Underlying Logic Pattern Strings are immutable. So the real workflow is: ➡️ Traverse (for loop) ➡️ Extract (charAt(i)) ➡️ Validate (conditions) ➡️ Build new string String result = ""; for (int i = 0; i < s.length(); i++) { char ch = s.charAt(i); if (Character.isLetterOrDigit(ch)) { result += ch; } } ⚡ Level Up: Rearranging the String New problem: 👉 Uppercase -> Lowercase -> Numbers (remove specials) Two approaches: Approach 1 (naive): 3 loops -> O(3n) Approach 2 (optimized): 1 loop + 3 strings -> O(n) String uc="", lc="", nc=""; for(char ch : s.toCharArray()){ if(ch >= 'A' && ch <= 'Z') uc += ch; else if(ch >= 'a' && ch <= 'z') lc += ch; else if(ch >= '0' && ch <= '9') nc += ch; } return uc + lc + nc; 👉 Same result. Better thinking. 💣 The Dangerous Bug (ASCII Trap) You try to sum numbers: sum += ch; Output? ❌ 155 instead of 11 Why? 👉 '2' = 50, '4' = 52, '5' = 53 👉 You added ASCII, not actual numbers 🔥 Fix: sum += (ch - '0'); 👉 Converts char -> actual digit ⚠️ Operator Precedence Trap This looks harmless: result += ch + 32; But gives ❌ "H32E32..." Why? 👉 String + char + int -> left to right evaluation 🔥 Fix: result += (char)(ch + 32); 🔄 Case Conversion Logic (No Inbuilt Methods) Key insight: 👉 'A' → 'a' difference = 32 So: Upper → Lower → +32 Lower → Upper → -32 if(ch >= 'A' && ch <= 'Z'){ result += (char)(ch + 32); }else{ result += ch; } 🔁 Swap Case Logic if(ch >= 'A' && ch <= 'Z'){ result += (char)(ch + 32); } else if(ch >= 'a' && ch <= 'z'){ result += (char)(ch - 32); } else{ result += ch; } 👉 Clean. No shortcuts. Pure logic. #Java #CodingInterview #ProblemSolving #Developers #LearnToCode #Programming #TechCareers #CodeSmart #CoreJava #Strings #Logics #Thinking #Coding #Upskilling #Problems #Syntax #DSA #TAPAcademy #Software #Development #Learning

If anyone is interested in developing their skills in Object-Oriented Programming (OOP), a quick thought based on my experience that might be helpful. 💬 Here are some tips for developing this skill.If anyone is interested in developing their skills in Object-Oriented Programming (OOP), here are a few tips based on my experience that might help: 💬 I personally learned OOP from W3Schools, and it gave me a strong foundation to understand the basics clearly. 💡 Here are some tips for developing this skill: * Start with the fundamentals: understand concepts like classes, objects, inheritance, encapsulation, and polymorphism. * Practise consistently by writing small programs and projects. * Break problems into smaller parts and solve them using OOP principles. * Read and learn from other people’s code to see how OOP is applied in real-world scenarios. * Be patient and keep improving step by step. OOP takes time to master, but with practise land the right resources, you can become confident in using it.

✨ LEARNING TAP Academy One of the fundamental pillars of Object-Oriented Programming (OOPS) is ABSTRACTION. 🔹 What is Abstraction? Abstraction is the concept of hiding implementation details and showing only the essential features of an object. 🔹 Abstract Class An abstract class is a restricted class that cannot be used to create objects. It acts as a blueprint for other classes. 🔹 Abstract Method An abstract method contains only the method signature (declaration) and no body (implementation). 💡 Key Points to Remember: ✔ An abstract class can inherit from another abstract class ✔ An abstract class can also inherit from a normal class ✔ A normal class can inherit from an abstract class ✔ An abstract class can have both abstract methods and concrete (normal) methods ✔ abstract and final keywords cannot be used together 💻 Example Program (Java): abstract class Animal { abstract void sound(); // abstract method void eat() { // concrete method System.out.println("Animal eats food"); } } class Dog extends Animal { void sound() { System.out.println("Dog barks"); } } public class Main { public static void main(String[] args) { // Animal a = new Animal(); ❌ Not allowed Dog d = new Dog(); d.sound(); d.eat(); } } 📌 Output: Dog barks Animal eats food ✨ Understanding abstraction helps you write cleaner, more secure, and maintainable code by focusing only on what is necessary. #Java #OOPS #Abstraction #Programming #TapAcademy #Learning #Coding

🚀 What is OOP (Object-Oriented Programming)? Object-Oriented Programming (OOP) is a programming paradigm that organizes code into objects — combining data and behavior together. Here’s a simple trick to keep it in order 👉 PEI 🔑 Core Concepts of OOP: ✔️ Encapsulation – Keep data safe by restricting access ✔️ Inheritance – Reuse code from existing classes ✔️ Polymorphism – One interface, multiple behaviors ✔️ Abstraction – Hide complexity, show only essentials 💡 Why OOP matters? • Makes code more modular & reusable • Improves maintainability • Helps build scalable applications • Reflects real-world problem solving 🌍 From small apps to enterprise systems, OOP is the backbone of modern development. 👉 Whether you're working with C#, Java, or Python — mastering OOP is a must for every developer. What’s your favorite way to remember OOP concepts? 🚀 Comment Here #OOP #Programming #SoftwareDevelopment #Coding #Tech #Developers #Learning #CareerGrowth

I am developing a dynamically typed, object-oriented, garbage-collected programming language written in pure Rust. Meet Scarlet, Scarlet is a programming language built in Rust. It compiles source code to Bytecode and executes it on a stack-based virtual machine, with the entire runtime weighing in at just ~500 KB. Scarlet runs natively as a CLI tool and also compiles to WebAssembly for embedded use in browsers and Node.js environments. ✅ Bytecode Compilation: Single-pass Pratt parser that emits bytecode directly, no AST built. ✅ Stack-based VM: Virtual machine with closures, upvalues, and call frames supporting functions as first class data types. ✅ Garbage Collection: Tri-color mark-and-sweep, self-growing Garbage collector. ✅ Object-Oriented: Classes, single inheritance, this, super, and constructors via init. ✅ String Interning: Identical strings share a single allocation for O(1) equality checks. ✅ Bitwise Operators: Full support for &, |, ^, !, <<, >> on integer operands. ✅ Native Functions: Built-in I/O, type introspection, coercion, and timing, platform-gated for WASM. ✅ WebAssembly Target: Compiles to .wasm for web, bundler, and Node.js targets via wasm-pack. ✅ REPL: Interactive session with persistent state across lines. ✅ Debug Mode: Annotated bytecode disassembly for tracing execution. Scarlet's here on Github: https://lnkd.in/gw2sNCDF I am building Scarlet as a recreational project, following the clox implementation of the Lox language from the great Crafting Interpreters book by Bob Nystrom. It was a pain to build the virtual machine, fighting the borrow checker. I wish I could have pivoted to a different language earlier. I have solved the famous Reverse Nodes in K-Group problem from LeetCode https://lnkd.in/g6ihmfaT in my own programming language - the algorithm is attached below. I would like to thank Dr. Prasina Sathish m'am, Dinesh D. sir and R. Gowri Thirugnanam ma'am and my class faculty for their encouragement and for fostering a healthy programming culture in our department and college.

💻 Coding is not just about writing code… It’s about creating something from nothing. From simple logic ➝ to complex patterns From lines of code ➝ to real outputs Whether it’s: • Generating patterns • Building visual designs • Solving logical problems Every small program improves your thinking. At first, it looks difficult. But once you understand the logic… It becomes creativity. 🚀 Code is not just syntax. It’s thinking. #Python #Coding #Programming #Developers #Learning #Tech

Day 15 | Programming Classes at TAP Academy 🧠 Multiple Arrays 🔹 1. Sorted arrays Instead of brute force, we learned to observe patterns first. Example: Finding the largest repeating element in a sorted array. 👉 Instead of scanning from the beginning, start from the end. 👉 Why? Because the largest element always sits at the last. 👉 Compare adjacent elements once. If equal → done. If not → move backward. Mini logic: for (int i = n-1; i > 0; i--) {   if (arr[i] == arr[i-1]) return arr[i]; } Simple logic. Clean code. Faster solution. 🔹 2. One problem → multiple variations The same structure can solve: • largest repeating element • smallest repeating element • largest repeating even element • prime repeating element Just tweak the condition: if (arr[i] == arr[i-1] && arr[i] % 2 == 0) Once logic is strong, variations become easy. 🔹 3. Common elements in two sorted arrays Big lesson here: avoid nested loops. Instead: 👉 Use two pointers (i & j) 👉 Compare step-by-step 👉 Move only the smaller pointer 👉 Print once when equal Mini logic: while (i < n && j < m) {   if (a[i] == b[j]) { print(a[i]); i++; j++; }   else if (a[i] < b[j]) i++;   else j++; } Cleaner. Faster. No duplicates. 🔹 4. Merging sorted arrays = thinking like the brain Before coding, ask: 👉 What should the result look like? 👉 Why does each number go where it goes? Mini logic: while (i < n && j < m) {   if (a[i] <= b[j]) res[k++] = a[i++];   else res[k++] = b[j++]; } Then don’t forget leftovers: while (i < n) res[k++] = a[i++]; while (j < m) res[k++] = b[j++]; That tiny detail decides whether your code passes or fails. #Programming #ProblemSolving #DSA #CodingJourney #LearningToCode #LogicBuilding #TAPAcademy #Java #Upskilling #Learning #Arrays #Logics

🚀 Mastering OOP Inheritance: Supercharge Your Coding Skills! 🌟 Inheritance in OOP is like passing on genetic traits, but for code! 🧬✨ Simply put, it allows a new class to inherit properties and methods from an existing one. For developers, this means reusability, efficiency, and easier maintenance of codebases. 🤖⚡️ Let's break it down: 1️⃣ Create a parent class with common attributes and behaviors. 2️⃣ Define child classes that inherit from the parent class. 3️⃣ Access parent class elements using super() method. 👩💻 Pro tip: Utilize inheritance to avoid code repetition and build scalable applications! 🌟 🛑 Common mistake: Forgetting to call super() in the child class constructor can lead to unexpected errors. Oops! 🙈 🤔 What's your favorite use case for inheritance in your projects? Share with us below! 💬 🌐 View my full portfolio and more dev resources at tharindunipun.lk 🚀 #OOP #Inheritance #CodeReuse #ProgrammingTips #DeveloperLife #ObjectOrientedProgramming #CodeEfficiency #SoftwareDevelopment #ProDev #CodingCommunity