ArrayList Deep Dive: Java Collections Framework

Day 64 of Sharing What I’ve Learned 🚀 Understanding Multithreading — From Programs to Threads After exploring how Java collections help manage and traverse data efficiently, I started looking into something equally important — how programs actually execute and handle multiple tasks. That’s where multithreading comes in. Before diving deeper into threads, I decided to revisit the fundamentals and build a clearer understanding first: 🔹Program A program is simply a set of instructions written in a language like Java. It’s what we write — but not yet running. 🔹Process When we run a program, it becomes a process. A process is an active instance of a program with its own memory and resources. 🔹Thread A thread is an independent set of code or the smallest unit of execution inside a process. Each process can have multiple threads working simultaneously. 🔹Multithreading Multithreading means running multiple threads within a single process. Instead of doing tasks one by one, we can perform multiple operations at the same time. 🔹Why it matters In real-world applications, tasks often need to happen together: 👉 Handling multiple users in an application 👉 Performing background tasks 👉 Improving performance and responsiveness Without multithreading, everything would run sequentially — slower and less efficient. 🔹Simple perspective Program → What we write Process → What runs Thread → What actually executes 🔹My realization Until now, I focused on how data is stored and traversed. Now it’s time to understand how execution can be optimized and made more efficient. 👉 Collections manage data 👉 Threads manage execution And both together are what make applications powerful. This is just the beginning — next, I’ll dive into how to create and manage threads in Java. #Java #Multithreading #Programming #JavaDeveloper #100DaysOfCode #DeveloperJourney #Day64 Grateful for guidance from TAP Academy Sharath R kshitij kenganavar

🚀 Day 55 of #100DaysOfCode — Getting Started with Multithreading in Java Over the past 2 days, I explored one of the most important concepts in Java: Multithreading 🔥 💡 What I Learned 🧵 What is Multithreading? Multithreading allows a program to execute multiple tasks simultaneously, improving performance and efficiency ⚡ 👉 Instead of running tasks one after another, we can run them in parallel. ⚙️ Creating Threads in Java 1️⃣ Using Thread Class Extend the Thread class Override the run() method Start using start() 2️⃣ Using Runnable Interface (Best Practice ✅) Implement Runnable Pass it to a Thread object Start execution using start() 🧠 Key Takeaways ✔ Runnable is preferred over Thread (better design & flexibility) ✔ Supports multiple inheritance ✔ Separates task from execution ✔ Helps in building scalable backend systems ⚠️ Important Concept 👉 Difference between: run() ❌ (normal method call) start() ✅ (creates new thread) 🔥 Real-World Use Cases Backend APIs Payment systems Real-time applications Inventory & billing systems (like the one I'm building 🏪) 🚀 What’s Next? ➡️ Synchronization ➡️ Race Conditions ➡️ ExecutorService (Thread Pool) Learning multithreading feels like unlocking a new level in Java 💪  Huge thanks to my mentor Suresh Bishnoi for simplifying complex concepts like multithreading and pushing me to keep learning consistently. #Java #Multithreading #100DaysOfCode #BackendDevelopment #LearningJourney

Day 73 of #90DaysDSAChallenge Solved LeetCode 451: Sort Characters By Frequency Learned an important Java design concept today. Problem Overview: The task was to sort characters in a string based on descending frequency. What confused me initially: Why create a separate Freq class instead of just using HashMap and PriorityQueue directly? Key Learning: PriorityQueue stores one complete object at a time. For this problem, each item needs two pieces of data together: Character Frequency Example: Instead of storing: e and 2 separately We package them as: Freq('e', 2) That custom class acts like a container holding both values in one object, so PriorityQueue can compare and sort them correctly. Why this matters: This taught me that custom classes in Java are often not about complexity, they simply bundle related data into one manageable unit. Alternative approach: We can also use Map.Entry<Character, Integer> instead of creating a custom class, but building Freq makes the logic easier to understand while learning. Today’s takeaway: Not every class is for business logic — sometimes it exists just to package data cleanly. #Java #90DaysDSAChallenge #LeetCode #PriorityQueue #HashMap #CodingJourney #ProblemSolving

Exploring one of the most powerful concepts in Java — Polymorphism, and I achieved it using Inheritance with a simple Plane program. In Java, polymorphism allows a single object to take multiple forms. Using inheritance and method overriding, I implemented a Plane example where different types of planes (like Cargo Plane and Passenger Plane) show different behaviors even though they share a common parent class. It was really interesting to see how a parent class reference can call different implementations at runtime — making the program dynamic and flexible. A big thank you to TAP Academy for teaching this concept so clearly and effortlessly. The real-time examples, like the Plane program, made it much easier to understand how inheritance and polymorphism work together. Excited to apply these concepts in real-world projects and keep growing 🚀 #Java #OOP #Polymorphism #Inheritance #CodingJourney #Learning #SoftwareDevelopment #TAPAcademy

Day 56 of Sharing What I’ve Learned🚀 TreeSet in Java — Sorted & Unique Elements After exploring how LinkedHashSet maintains insertion order, I moved to something even more powerful — TreeSet. 👉 It not only stores unique elements but also keeps them automatically sorted 🔹 What is TreeSet? TreeSet is an implementation of the Set interface that stores unique elements in sorted order. 👉 It is internally based on a Red-Black Tree (self-balancing binary search tree) 🔹 How does TreeSet store & sort data? 👉 Elements are stored in a tree structure, not randomly 👉 While inserting, elements are placed in a way that keeps the tree balanced 👉 Data is always arranged in ascending order (default) ✔ Smallest element → left side ✔ Largest element → right side ✔ In-order traversal → gives sorted output 🔹 Why use TreeSet? ✔ Sorted Data Elements are always in ascending order ✔ No Duplicates Just like other Sets, duplicates are not allowed ✔ Navigable Operations Supports methods like higher(), lower(), ceiling(), floor() 🔹 Key Features ✔ Stores unique elements ✔ Automatically sorts elements ✔ Does NOT allow null values ✔ Slower than HashSet & LinkedHashSet (due to sorting) 🔹 Important Methods ✔ add() ✔ remove() ✔ contains() ✔ first() / last() ✔ higher() / lower() 🔹 When should we use TreeSet? 👉 Use TreeSet when: ✔ You need sorted data ✔ You want range-based operations ✔ You need navigation (greater/smaller elements) 🔹 When NOT to use? ❌ When order doesn’t matter → use HashSet ❌ When insertion order matters → use LinkedHashSet ❌ When performance is critical (faster ops needed) 🔹 Key Insight 💡 TreeSet is like a self-sorting set — 👉 You don’t sort the data, it sorts itself automatically 🔹 Day 56 Realization 🎯 Data structures are not just about storing data… 👉 they define how efficiently you can retrieve, organize, and use it #Java #TreeSet #DataStructures #CollectionsFramework #Programming #DeveloperJourney #100DaysOfCode #Day56 Grateful for guidance from, Sharath R TAP Academy

Access modifiers in Java confused me more than inheritance at first. Not because they are complex — but because I didn’t understand where they actually matter. This diagram helped me connect the dots 👇 Here’s what finally made sense: • public → no restrictions • private → only inside the class • default → package-level access • protected → the tricky one → works like default → BUT also accessible through inheritance (even outside the package) Access modifiers are not just about visibility — they define how safely and cleanly your code interacts across packages. That’s where Java moves from syntax → design. Grateful to TAP Academy and Harshit T sir for breaking this down clearly Which modifier took you the longest to understand? #Java #OOP #AccessModifiers #SoftwareDevelopment #LearningJourney

🚀 Day 75 — LeetCode Practice 🚀 Today’s problem: To Lower Case 💡 What I learned today: • Understood how to convert characters using built-in string methods • Learned the importance of string immutability in Java • Practiced writing clean and minimal code • Realized that sometimes the simplest problems reinforce core concepts 🧠 Key Idea: Use Java’s inbuilt function: toLowerCase() → converts all uppercase letters to lowercase easily 🔥 Takeaway: Not every problem needs complex logic — knowing the right method saves time ⏱️ Consistency > Complexity 💯 #Day75 #LeetCode #Java #DSA #CodingJourney #Consistency #Learning

☕ Learn Java with Me — Day 8 One variable for every value? That gets messy very fast. Today we learned something that makes code much smarter: 👉 Arrays in Java Instead of this: int a = 10; int b = 20; int c = 30; We can simply write: int[] numbers = {10, 20, 30}; Simple. Cleaner. Much more efficient. This is where Java starts feeling practical. From basics → real logic building 🚀 Week 2 already feels exciting. We’re learning together 🤝 #java #coding #arrays #learning #showup

Day 91 of #100DaysOfLeetCode 💻✅ Solved #875. Koko Eating Bananas problem in Java. Approach: • Used Binary Search on possible eating speeds • Set range from 1 to maximum pile • Checked feasibility using helper function • Narrowed down to minimum valid speed Performance: ✓ Runtime: 6 ms (Beats 99.77% submissions) 🚀 ✓ Memory: 47.78 MB (Beats 76.18% submissions) Key Learning: ✓ Mastered Binary Search on answer space ✓ Learned handling ceil calculations efficiently ✓ Improved optimization using helper functions Learning one problem every single day 🚀 #Java #LeetCode #DSA #BinarySearch #Arrays #ProblemSolving #CodingJourney #100DaysOfCode

🚀 Day 58 at Tap Academy – Core Java Journey Today’s session was all about understanding powerful data structures and concepts that improve performance and efficiency in Java. 📚 What I learned today: 🔹 HashSet and its features 🔹 Hashing, Hash Functions & Hash Table properties 🔹 Load Factor and Bucket Locations 🔹 When to use HashSet effectively 🔹 LinkedHashSet and its advantages 🔹 Introduction to Map interface 🔹 HashMap and LinkedHashMap concepts These concepts helped me understand how data is stored, retrieved, and managed efficiently using hashing techniques. It’s exciting to see how these structures play a crucial role in real-world applications! 💡 Every day is a step closer to becoming a better developer. #Java #CoreJava #LearningJourney #TapAcademy #Programming #DataStructures #100DaysOfCode #DeveloperLife