ArrayDeque vs LinkedList in Java

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 10/100 – Java Practice Challenge 🚀 Continuing my #100DaysOfCode journey with another important Java concept. 🔹 Topic Covered: Polymorphism Polymorphism means “many forms” — the same method behaves differently depending on the object. 💻 Practice Code: 🔸 Example Program class Animal { void sound() { System.out.println("Animal makes sound"); } } class Dog extends Animal { @Override void sound() { System.out.println("Dog barks"); } } public class Main { public static void main(String[] args) { Animal a = new Dog(); // Upcasting a.sound(); // Runtime polymorphism } } 📌 Key Learnings: ✔️ Same method → different behavior ✔️ Achieved using method overriding ✔️ Based on object type (runtime) 🎯 Focus: Understanding dynamic behavior using inheritance and method overriding 🔥 Interview Insight: Polymorphism is a core OOP concept and widely used in real-world applications. #Java #100DaysOfCode #Polymorphism #OOP #JavaDeveloper #Programming #LearningInPublic

Day 11/100 – Java Practice Challenge 🚀 Continuing my #100DaysOfCode journey with another important Java concept. 🔹 Topic Covered: Compile-time vs Runtime Polymorphism 💻 Practice Code: 🔸 Compile-time Polymorphism (Method Overloading) class Calculator { int add(int a, int b) { return a + b; } int add(int a, int b, int c) { return a + b + c; } } 🔸 Runtime Polymorphism (Method Overriding) class Animal { void sound() { System.out.println("Animal sound"); } } class Cat extends Animal { @Override void sound() { System.out.println("Cat meows"); } } public class Main { public static void main(String[] args) { // Compile-time Calculator c = new Calculator(); System.out.println(c.add(10, 20)); System.out.println(c.add(10, 20, 30)); // Runtime Animal a = new Cat(); a.sound(); } } 📌 Key Learnings: ✔️ Compile-time → method decided at compile time ✔️ Runtime → method decided at runtime ✔️ Overloading vs Overriding difference 🎯 Focus: Understanding how Java resolves method calls 🔥 Interview Insight: Difference between compile-time and runtime polymorphism is one of the most frequently asked Java interview questions. #Java #100DaysOfCode #MethodOverloading #MethodOverriding #Polymorphism #JavaDeveloper #Programming #LearningInPublic

🚀 **Day 4 of My DSA Journey in Java** Today, I took my first real step into writing Java programs and understanding how code actually works behind the scenes. 🔹 Learned about **functions/methods** — reusable blocks of code designed to perform specific tasks, along with the concept of input and output. 🔹 Understood the importance of the **main() function** — the entry point where every Java program begins execution. 🔹 Wrote my first **Hello World program** using `System.out.println()` 🎉 🔹 Explored the difference between `print` and `println` for output formatting. 🔹 Learned how to use **comments** (`//` and `/* */`) to make code more readable and maintainable. 🔹 Got introduced to the structure of classical Java syntax like `public static void main`. One key takeaway: not everything needs to be mastered instantly — some concepts are okay to understand at a basic level now and explore deeply later. Slowly building consistency and strengthening my fundamentals 💻✨ #DSA #Java #LearningJourney #Coding #Programming #Beginners #Consistency

#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

🚀 Day 47 of My Learning Journey – Java Wrapper Classes Today, I explored Wrapper Classes in Java, an important concept that bridges primitive data types and objects. 🔍 What I Learned: ✔️ Wrapper classes convert primitive data types into objects ✔️ Each primitive type has a corresponding wrapper class (e.g., int → Integer, char → Character, double → Double) ✔️ Enables use of primitives in collections like ArrayList 💡 Key Concepts: 🔹 Autoboxing – Automatic conversion of primitive to object 🔹 Unboxing – Converting object back to primitive 🔹 Useful methods like parseInt(), toString(), and valueOf() 📊 Why It Matters: Wrapper classes make Java more flexible by allowing primitives to be treated as objects, especially when working with frameworks and collections. 📌 Example Use Case: Storing integers in an ArrayList using Integer instead of int. 🎯 Takeaway: Understanding wrapper classes is essential for writing efficient and modern Java programs. #Java #LearningJourney #Programming #Day47 #TechSkills #Developers #Coding

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

🚀 Exploring Java Collection Framework Today’s session was all about understanding the powerful Java Collection Framework and how it helps in managing and organizing data efficiently. Dived deep into core concepts like interfaces and classes in collections, and explored the three main interfaces: List, Set, and Map. Gained clarity on how these structures differ and where to use them in real-world applications. Focused on the ArrayList class—its properties like dynamic resizing, ordered storage, and index-based access—making it one of the most commonly used collection classes in Java. Also understood the hierarchy of ArrayList, how it is part of the List interface, and how it inherits behavior from abstract classes like AbstractList and AbstractCollection. 📚 A strong foundation in collections is essential for writing efficient and scalable Java applications. TAP Academy #Java #CollectionsFramework #ArrayList #Programming #LearningJourney #FullStackDevelopment

🚀 Mastering TreeSet in Java: Hierarchy & Powerful Methods While diving deeper into the Java Collections Framework, I explored the structure and capabilities of TreeSet—a class that combines sorting, uniqueness, and efficient navigation. 🔷 TreeSet Hierarchy (Understanding the Backbone) The hierarchy of TreeSet is what gives it its powerful features: 👉 TreeSet ⬇️ extends AbstractSet ⬇️ implements NavigableSet ⬇️ extends SortedSet ⬇️ extends Set ⬇️ extends Collection ⬇️ extends Iterable 💡 This layered structure enables TreeSet to support sorted data, navigation operations, and collection behavior seamlessly. 🔷 Important Methods in TreeSet TreeSet provides several methods for efficient data handling and navigation: 📌 Basic Retrieval first() → Returns the first (smallest) element last() → Returns the last (largest) element 📌 Range Operations headSet() → Elements less than a given value tailSet() → Elements greater than or equal to a value subSet() → Elements within a specific range 📌 Removal Operations pollFirst() → Removes and returns first element pollLast() → Removes and returns last element 📌 Navigation Methods ceiling() → Smallest element ≥ given value floor() → Largest element ≤ given value higher() → Element strictly greater than given value lower() → Element strictly less than given value 🔷 When to Use TreeSet? TreeSet is the right choice when you need: ✔️ Sorted Order (automatic ascending order) ✔️ No Duplicate Entries ✔️ Efficient Range-Based Operations ✔️ Navigation through elements (closest matches) 📊 Time Complexity: Insertion → O(log n) Access/Search → O(log n) 💡 Key Insight: TreeSet internally uses a self-balancing tree (Red-Black Tree), which ensures consistent performance and sorted data at all times. 🎯 Understanding TreeSet not only strengthens your knowledge of collections but also helps in solving real-world problems involving sorted and dynamic datasets. #Java #TreeSet #JavaCollections #Programming #DataStructures #LearningJourney TAP Academy

🚀 Mastering ArrayDeque in Java — A Powerful Alternative to Stack & Queue If you're working with Java collections, one underrated yet powerful class you should know is ArrayDeque. It’s fast, flexible, and widely used in real-world applications. Here’s a crisp breakdown 👇 🔹 What is ArrayDeque? ArrayDeque is a resizable-array implementation of the Deque interface, which allows insertion and deletion from both ends. 💡 Key Features of ArrayDeque ✔️ Default initial capacity is 16 ✔️ Uses a Resizable Array as its internal data structure ✔️ Capacity grows using: CurrentCapacity × 2 ✔️ Maintains insertion order ✔️ Allows duplicate elements ✔️ Supports heterogeneous data ❌ Does NOT allow null values 🛠️ Constructors in ArrayDeque There are 3 types of constructors: 1️⃣ ArrayDeque() → Default capacity (16) 2️⃣ ArrayDeque(int numElements) → Custom initial capacity 3️⃣ ArrayDeque(Collection<? extends E> c) → Initialize with another collection 🔍 Accessing Elements Unlike Lists, ArrayDeque has some restrictions: ❌ Cannot use: Traditional for loop (index-based) ListIterator ✅ You can use: for-each loop Iterator Descending Iterator (for reverse traversal) 🧬 Hierarchy of ArrayDeque Iterable ↓ Collection ↓ Queue ↓ Deque ↓ ArrayDeque 👉 In simple terms: ArrayDeque implements Deque Deque extends Queue Queue extends Collection Collection extends Iterable 🔥 Why use ArrayDeque? ✔️ Faster than Stack (no synchronization overhead) ✔️ Efficient double-ended operations ✔️ Ideal for sliding window, palindrome checks, and BFS/DFS algorithms 💬 Final Thought If you're still using Stack, it might be time to switch to ArrayDeque for better performance and flexibility! #Java #DataStructures #ArrayDeque #Programming #JavaCollections #CodingInterview #SoftwareDevelopment TAP Academy