Learning Mutable Strings in Java with StringBuffer & StringBuilder

Day 49 of Sharing What I’ve Learned🚀 ArrayList in Java In the Java Collections Framework, ArrayList is one of the first classes that helps manage data easily and efficiently. 🔹 What is ArrayList? ArrayList is a dynamic array in Java that can grow and shrink automatically as elements are added or removed. Unlike normal arrays, you don’t need to worry about size — it manages that internally. 🔹 Key Features ✔ Maintains insertion order ✔ Allows duplicate elements ✔ Provides fast random access (index-based) ✔ Automatically resizes when needed 🔹 Why Not Use Arrays? Traditional arrays have limitations: ❌ Fixed size ❌ Manual resizing ❌ Less flexibility ArrayList solves all of these problems with built-in methods. 🔹 Common Methods ✔ add() → Insert elements ✔ get() → Access elements ✔ set() → Update elements ✔ remove() → Delete elements ✔ size() → Get total elements 🔹 Example import java.util.ArrayList; public class Demo { public static void main(String[] args) { ArrayList<String> list = new ArrayList<>(); list.add("Java"); list.add("Python"); list.add("Java"); // duplicate allowed System.out.println(list); // [Java, Python, Java] list.remove("Python"); System.out.println(list.get(0)); // Java } } 🔹 When to Use ArrayList? ✔ When you need frequent data access ✔ When order matters ✔ When duplicates are allowed ✔ When size is not fixed 🔹 Key Insight ArrayList is powerful, but not always the best choice. If your use case involves frequent insertions/deletions in the middle, other structures like LinkedList may perform better. 🔹 Realization Learning ArrayList made me realize something important — Java is not just about writing logic, it’s also about choosing the right structure to support that logic. #Java #CoreJava #ArrayList #CollectionsFramework #DataStructures #Programming #DeveloperJourney #100DaysOfCode #CodingJourney #Day49 Grateful for guidance from, Sharath R TAP Academy

Day 40 of Learning Java: Method Overloading Instead of creating different method names for similar tasks, we can use the same method name but change the parameters — and Java figures out which one to call. -So what exactly is Method Overloading? It’s when multiple methods in the same class have: ✔ Same name ✔ Different parameter list That’s it. Simple idea, but very powerful. -Ways to overload a method • Change the type of parameters • Change the number of parameters • Change the order of parameters Example- Think of a login system: Login using username + password Login using mobile + password Both are login actions, right? So instead of writing different method names, we just overload: login(String username, String password) login(long mobile, String password) Same method name → different ways to use it -Another relatable one Payment systems 👇 COD UPI Card Net Banking Instead of: paymentByUPI(), paymentByCard()… We can just do: payment() payment(String upi) payment(long card) payment(String user, String pass) - Important things I learned • Just changing return type won’t work (it gives error) • Overloading happens at compile time • Works with static, private, and even final methods • Yes, even main() can be overloaded (but JVM only runs the standard one) #Java #LearningInPublic #100DaysOfCode #Programming #OOP #CodingJourney

🚀 Exploring Method Overloading in Java As part of my journey in mastering Object-Oriented Programming in Java, I recently explored one of the most powerful concepts of Polymorphism — Method Overloading. 💡 What is Method Overloading? Method overloading is the process of creating multiple methods with the same name in a class, but with different parameter lists. It allows the same action to behave differently based on the input — making programs more flexible and readable. 🔹 Three Ways to Achieve Method Overloading A method can be overloaded by changing: 1️⃣ Number of parameters 2️⃣ Data types of parameters 3️⃣ Order/sequence of parameters ❌ Invalid Case If two methods have the same name + same parameters but different return types, it is NOT valid overloading and results in a compile-time error. Example: int area(int, int) float area(int, int) → Compilation Error 🚫 🧠 Why is it called False (Virtual) Polymorphism? To the user, it looks like one method performing multiple tasks (one-to-many). But internally, each call maps to a separate method (one-to-one) — hence the term False Polymorphism. ⚡ Type Promotion in Overloading If an exact match is not found, Java automatically promotes smaller data types to larger ones: byte → short → int → long → float → double This makes method overloading even more powerful and flexible! 👩💻 Simple Example class AreaCalculator { int area(int l, int b) { return l * b; } double area(double r) { return 3.14 * r * r; } int area(int side) { return side * side; } } TAP Academy ✨ Learning these core OOP concepts is helping me build stronger foundations in Java and improve my problem-solving skills step by step. #Java #OOP #Programming #CodingJourney #ComputerScience #LearningInPublic 

Day 41 of Learning Java: Method Overriding If method overloading was about flexibility,method overriding is about customization. What is Method Overriding? It’s when a subclass provides its own implementation of a method that is already defined in the parent class. Same method name. Same parameters. But different behavior. 🔹 Simple example- class Parent { void watchTV() { System.out.println("Watching News/Serial"); } } class Child extends Parent { @Override void watchTV() { System.out.println("Watching Music/Sports"); } } Same method → different output depending on the object. • Parent defines a general behavior • Child modifies it based on its own need • This helps in writing more flexible and reusable code 🔹 Key points to remember • Method signature must be the same • Happens during runtime (runtime polymorphism) • Inheritance is required 👉 You cannot override: static methods private methods final methods 🔹 One important concept Parent ref = new Child(); ref.watchTV(); Even though the reference is of Parent, the method of Child gets executed. 👉 This is called dynamic method dispatch 🔹 About @Override It’s not mandatory, but it helps: ✔ Avoid mistakes ✔ Makes code more readable ✔ Ensures you’re actually overriding #Java #OOP #MethodOverriding #LearningInPublic #Programming#sql #branding

🚀 Day 56 & 57 – Mastering Maps in Java | Tap Academy Diving deeper into the Java Collections Framework, I explored one of the most powerful concepts — Maps, especially HashMap, LinkedHashMap, and TreeMap. 🔹 Day 56 Highlights – HashMap Understood how Map stores data in key–value pairs Learned internal working: Hashing (Hash Table + Hash Function) Explored default capacity (16) and load factor (75%) Practiced key features: ✔ No duplicate keys ✔ Allows null values ✔ Heterogeneous data support ✔ Fast operations → O(1) 💻 Implemented important methods: put(), get(), containsKey(), containsValue(), entrySet(), keySet(), values() 🔁 Learned how to iterate using: entrySet() (Map → Set conversion) Iterator (cursor-based access) 🔹 Day 57 Highlights – LinkedHashMap & TreeMap 📌 LinkedHashMap Maintains insertion order Same features as HashMap but ordered output 📌 TreeMap Stores data in sorted order (ascending by keys) Uses Tree structure (Red-Black Tree) No null keys allowed Slightly slower → O(log n) 📊 Comparison Insight HashMap → Fastest, no order ⚡ LinkedHashMap → Maintains insertion order 📌 TreeMap → Sorted order 🔄 🎯 Key takeaway: Choosing the right data structure matters based on requirement — speed, order, or sorting. 🎯 This journey is strengthening my problem-solving skills and deepening my understanding of how real-world data is handled efficiently. #Java #CollectionsFramework #HashMap #LinkedHashMap #TreeMap #DataStructures #FullStackJava #TapAcademy #LearningJourney 🚀

Day 37 of Learning Java Today I learned something interesting Illegal Forward Reference in Java. At first, it sounded complicated, but once I understood it, it actually made a lot of sense! Here’s what I learned: 🔹 What is Illegal Forward Reference?   • It happens when you try to use a variable before it is declared.   • Java doesn’t allow referencing a variable that comes later in the code. 🔹 Why does it happen?   • Java reads code from top to bottom.   • If a variable is used before it exists, the compiler throws an error. 🔹 Example of the issue:   • Using a variable before declaring & defining it to a compile-time error. 🔹 How to fix it?   • Always declare variables before using them.   • we have to call static variable using ClassName.VarName. Thanks to my mentor Ashim Prem Mahto for the clear explanations and for always clearing my doubts. #Java #LearningJava #CodingJourney #Programming #DeveloperLife #CodeNewbie #JavaDeveloper #TechLearning #StudentLife #jvm

Day 39 of learning java Today I learned something very important in Java, Object Creation. Syntax: "className objectName = new constructor();" Here’s what I understood: • The left side ("className objectName") is just declaring a reference variable. • The right side ("new constructor()") is where the actual object is created. • Memory is allocated only when we use the "new" keyword. • The constructor gets executed automatically when the object is created. • Without "new", no memory is allocated and no constructor runs. In short: Declaration != Object creation You need "new" to actually create and use the object. This concept made things much clear about how Java handles memory and execution internally. Thanks to my mentor Ashim Prem Mahto for the clear explanations and for always clearing my doubts. #Java #LearningJourney #Programming #JavaBasics #CodingLife #DeveloperJourney #TechLearning #Beginners #CodeNewbie #jvm #SoftwareEngineer #StudentLife

Day 57 of Sharing What I’ve Learned🚀 PriorityQueue in Java — Processing Based on Priority After learning how TreeSet keeps elements sorted, I explored something even more practical — PriorityQueue. 👉 It doesn’t just store elements… it processes them based on priority 🔹 What is PriorityQueue? PriorityQueue is a part of the Java Collections Framework that stores elements in a way where the highest (or lowest) priority element is always processed first. 👉 It is internally based on a Heap (Min-Heap by default) 🔹 How does PriorityQueue work? 👉 Elements are not stored in full sorted order 👉 Only the head element is guaranteed to be the smallest (default) 👉 Insertion and removal maintain heap structure ✔ peek() → gives highest priority element ✔ poll() → removes highest priority element 🔹 Why use PriorityQueue? ✔ Priority-Based Processing Elements are handled based on importance, not insertion order ✔ Efficient Operations Insertion & deletion are faster than full sorting ✔ Real-World Use Cases 👉 Task scheduling 👉 CPU job scheduling 👉 Dijkstra’s Algorithm 👉 Event-driven systems 🔹 Key Features ✔ Allows duplicate elements ✔ Does NOT allow null values ✔ Not thread-safe ✔ Default is Min-Heap (smallest first) 🔹 Important Methods ✔ add() / offer() ✔ poll() ✔ peek() ✔ remove() 🔹 When should we use PriorityQueue? 👉 Use it when: ✔ You need to process elements by priority ✔ You don’t need full sorting ✔ You want efficient retrieval of min/max 🔹 When NOT to use? ❌ When you need full sorted traversal → use TreeSet ❌ When insertion order matters → use LinkedList/Queue ❌ When random access is required 🔹 Key Insight 💡 PriorityQueue doesn’t sort everything… 👉 It only guarantees the most important element comes first 🔹 Day 57 Realization 🎯 Not all problems need full sorting… 👉 Sometimes, knowing the “next most important” element is enough #Java #PriorityQueue #DataStructures #CollectionsFramework #Programming #DeveloperJourney #100DaysOfCode #Day57 Grateful for guidance from, Sharath R TAP Academy

📅 Day 45 of My Learning Journey Today, I explored two important concepts in Java: String Class and StringBuffer. 🔹 String Class Strings are immutable, meaning once an object is created, it cannot be changed. Any modification results in the creation of a new object. Widely used for safe and secure data handling. 🔹 StringBuffer StringBuffer is mutable, meaning it allows changes without creating new objects. It is thread-safe (synchronized), making it suitable for multi-threaded environments. Provides methods like append(), insert(), and reverse() for efficient string manipulation. 💡 Key Takeaway: Use String when data should remain constant, and StringBuffer when frequent modifications are required, especially in multi-threaded applications. 📌 Understanding the difference between immutability and mutability helps in writing optimized and efficient Java programs! #Day45 #Java #StringClass #StringBuffer #Programming #LearningJourney #TechSkills

#Day45 – Map in Java: Key-Value Pairs & Problem Solving -#Programming ⚠️ Today, I explored one of the most powerful data structures in Java — Map, which helps in storing data in key-value pairs and solving real-world problems efficiently. 💡 Key Learnings: ✔ Map → collection of key-value pairs ✔ Key → unique (no duplicates allowed) and Value → can have duplicates ✔ One key maps to exactly one value ✔ Methods: put(), get(), remove(), containsKey(), containsValue() ✔ keySet() → get all keys , values() → get all values ✔ entrySet() → get key-value pairs , size() and isEmpty() ✔ Types of Map → HashMap, LinkedHashMap, TreeMap ✔ HashMap → no order , LinkedHashMap → maintains insertion order ✔ TreeMap → sorts keys 🧠 Example Solved: Solved a problem to count the frequency of each character in a string (e.g., Mississippi → M1i4s4p2) using Map. Learned how to efficiently track occurrences using containsKey(), get(), and put() methods. A big thank you to TAP Academy, Harshit T Sir, and Somanna M G Sir for explaining complex concepts in such a simple and practical way. Your teaching style, real-world examples, and constant support have made a huge difference in my understanding of Java and problem-solving. 🙏 #Java #CollectionsFramework #Map #HashMap #LinkedHashMap #DataStructures #CodingJourney #Consistency