TreeSet Java: Sorted, Unique, and Powerful

Two Pointer Technique: Today I explored the Two Pointer approach in Java, and it completely changed how I look at array problems 👇 🔹 Instead of using nested loops (O(n²)), we can solve many problems in O(n) using two pointers. 💡 Basic Idea: - Use two pointers (left & right) - Move them based on conditions - Reduce unnecessary iterations 📌 Example: Move Zeroes - Keep a slow pointer for non-zero elements - Traverse with a fast pointer - Swap when needed This simple technique makes code more efficient and clean 🔥 Still learning, but improving step by step 💪 👉 What other problems can be solved using two pointers? Today I practiced the Two Pointer approach in Java using the "Move Zeroes" problem 👇 💡 Idea: - Use a slow pointer to track position of non-zero elements - Use a fast pointer to traverse the array - Swap when needed 🧠 Java Code: public class MoveZeroes { public static void moveZeroes(int[] arr) { int slow = 0; for (int fast = 0; fast < arr.length; fast++) { if (arr[fast] != 0) { int temp = arr[slow]; arr[slow] = arr[fast]; arr[fast] = temp; slow++; } } } public static void main(String[] args) { int[] arr = {1, 2, 0, 4, 3, 0, 5, 0}; moveZeroes(arr); for (int num : arr) { System.out.print(num + " "); } } } ⚡ Time Complexity: O(n) ⚡ Space Complexity: O(1) Small step, but feels great to understand optimization like this 🔥 👉 Any better approaches or suggestions? #Java #DSA #TwoPointers #LearningInPublic #CodingJourney

🚀 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 HashSet in Java: A Must-Know for Every Developer When working with collections in Java, ensuring uniqueness and fast performance is often critical. That’s where HashSet comes into play 👇 🔹 What is HashSet? HashSet is a part of the Java Collections Framework that implements the Set interface and is backed by a hash table (HashMap internally). It stores unique elements only and does not maintain any insertion order. 🔹 Why do we need HashSet? ✅ To store unique elements (no duplicates allowed) ✅ Provides constant time performance O(1) for basic operations (add, remove, contains) ✅ Ideal for searching, filtering, and removing duplicates ✅ Improves performance compared to lists when frequent lookups are required 👉 Real-world use case: Removing duplicate entries from a dataset or checking if an element already exists efficiently. 🔹 Key Methods in HashSet 📌 add(E e) → Adds an element 📌 remove(Object o) → Removes an element 📌 contains(Object o) → Checks if element exists 📌 size() → Returns number of elements 📌 isEmpty() → Checks if set is empty 📌 clear() → Removes all elements 📌 iterator() → Iterates through elements 🔹 Important Properties of HashSet ⚡ Does not allow duplicate elements ⚡ Allows only one null value ⚡ Unordered collection (no insertion order maintained) ⚡ Not synchronized (not thread-safe by default) ⚡ Backed by a HashMap for fast operations ⚡ Performance depends on hashing (hashCode & equals methods) 💡 Pro Tip: Always override hashCode() and equals() properly when storing custom objects in a HashSet to avoid unexpected duplicates. 🎯 Conclusion: Use HashSet when your priority is speed + uniqueness. It’s one of the most efficient data structures for handling large datasets with frequent lookup operations. #Java #DataStructures #HashSet #Programming #CodingInterview #JavaCollections #SoftwareEngineering TAP Academy

🚀 Java Collections Framework & ArrayList – Simple Notes While learning Java, I explored the Collections Framework and understood how it helps in storing and managing data efficiently. 🔹 What is Collections Framework? It is a group of classes and interfaces used to store, manipulate, and process data easily. 🔹 Why it was introduced? Earlier, we used arrays which had many limitations (fixed size, difficult operations). To overcome this, Java introduced Collections. 📌 Common Interfaces & Classes - List → ArrayList, LinkedList - Set → HashSet, TreeSet - Queue → Deque - Map → HashMap 💡 What is ArrayList? - A resizable (dynamic) array - Stores objects (not primitive data types) - Allows duplicate values - Maintains insertion order - Allows null values ⚙️ Constructors of ArrayList - "ArrayList()" → default - "ArrayList(int capacity)" → with initial size - "ArrayList(Collection c)" → from another collection 📈 Capacity Concept - Default capacity = 10 - When full, it increases using: 👉 "(current size × 3/2) + 1" 🔁 Ways to Access Elements 1. For loop 2. For-each loop 3. Iterator (forward only) 4. ListIterator (forward & backward) 🛠️ Important Methods - "add()" → add element - "add(index, value)" → add at position - "get()" → access element - "set()" → update value - "remove()" → delete element - "size()" → number of elements - "isEmpty()" → check empty or not - "contains()" → check element - "indexOf()" / "lastIndexOf()" → find position - "clear()" → remove all - "subList()" → get part of list - "trimToSize()" → reduce memory 📌 When to Use ArrayList? ✔ When you need dynamic size ✔ When duplicates are allowed ✔ When order matters ✔ When frequent read operations are needed ✨ In short: ArrayList makes data handling easy, flexible, and efficient compared to traditional arrays. #Java #Collections #ArrayList #Programming #Learning #CodingJourney

Java Strings – From Basics to Practical Understanding Today I dived deeper into Strings in Java, and this time I focused not just on concepts, but also on how things actually work behind the scenes. Here’s what I explored 👇 🔹 Different ways to create Strings (String Pool vs Heap Memory) 🔹 Why Strings are immutable and how that improves safety 🔹 The right way to compare Strings using .equals() 🔹 Commonly used String methods for real-world coding 🔹 When to use StringBuilder for better performance 🔹 And finally… understanding mutable strings using StringBuilder & StringBuffer One important realization: Not all strings behave the same — choosing between immutable and mutable approaches can directly impact performance and memory usage. Key Learning: 👉 Use normal Strings when data should not change 👉 Use StringBuilder when frequent modifications are needed This journey is helping me understand that writing efficient code is not just about syntax, but about making the right choices. More learning coming soon… #Java #JavaProgramming #CodingJourney #LearningInPublic #Developers #StringBuilder #ProgrammingBasics #100DaysOfCode

Learning Priority Queue in Java Recently, I explored the concept of Priority Queue in Java, and it gave me a strong understanding of how efficient data handling works when priority matters over order. 🔹 Why Priority Queue? Unlike normal queues (FIFO), a Priority Queue processes elements based on their priority (min or max), which makes it extremely useful in scenarios like scheduling, real-time systems, and optimization problems. 🔹 Key Learnings: How Priority Queue is implemented using a heap (min-heap by default) Syntax and basic operations in Java Time complexity for insertion and deletion: O(log n) How ordering works internally without full sorting 🔹 Java Syntax Example: PriorityQueue<Integer> pq = new PriorityQueue<>(); pq.add(10); pq.add(5); pq.add(20); System.out.println(pq.peek()); // Smallest element pq.poll(); // Removes smallest element 🔹 Problems I Practiced: ✔️ Kth Smallest Element ✔️ Kth Largest Element These problems helped me understand how to use min-heap and max-heap effectively to optimize performance instead of sorting the entire array. 💡 Takeaway: Priority Queue is a powerful tool when you need efficient access to the smallest or largest element without sorting everything. Looking forward to applying this in more real-world problems and system design scenarios! 💻🔥 big thanks to Pratyush Narain #Java #DataStructures #PriorityQueue #DSA #Learning #CodingJourney

💡 Java Concept: Exception Handling in Method Overriding 🚀 While learning Java, I discovered an important rule that many beginners miss 👇 👉 How exceptions behave when a child class overrides a parent method 🔹 Simple Definition When a subclass overrides a method, it cannot throw broader or new checked exceptions than the superclass. 🧠 Golden Rule 👉 Child class can: ✔ Throw same exception ✔ Throw smaller (child) exception ✔ Throw unchecked exception ✔ Throw no exception 👉 Child class cannot: ❌ Throw new checked exception (not in parent) 🔴 Example (Wrong ❌) class Parent { void show() { } } class Child extends Parent { void show() throws IOException { // ❌ Compile Error System.out.println("Child"); } } 👉 Reason: Parent didn’t declare any exception 🟢 Example (Correct ✅) class Parent { void show() throws Exception { System.out.println("Parent"); } } class Child extends Parent { void show() throws ArithmeticException { System.out.println("Child"); } } 👉 Allowed because: ✔ ArithmeticException is unchecked ✔ OR smaller than parent exception 💡 Why this rule exists? To maintain runtime safety and avoid unexpected errors Parent p = new Child(); p.show(); 👉 Compiler only knows Parent → so child cannot introduce new checked exceptions 🔥 Easy Trick to Remember 👉 "Child can reduce risk, but not increase it" 📌 Small concept, but very important for interviews & real-world coding! #Java #OOP #ExceptionHandling #Programming #Developers #Coding #SoftwareEngineering #LearningJourney

Continuing my Java learning journey by understanding Exception Handling, an essential concept for building robust and reliable applications. In Java, an exception is an event that occurs during program execution which disrupts the normal flow of the program. Exception Handling is used to handle such situations gracefully without crashing the application. Java provides a structured way to manage errors using keywords like: try catch finally throw throws 🔷 💡 Why Exception Handling is Important? Prevents program crashes Handles runtime errors smoothly Maintains normal flow of execution Improves application reliability Helps in debugging and error tracking 🔷 💡 Types of Exceptions 1️⃣ Checked Exceptions Checked at compile time Must be handled explicitly Example: File handling errors 2️⃣ Unchecked Exceptions Occur at runtime Caused by logical errors Example: Arithmetic errors, Null pointer 🔷 💡 Key Concepts try → block where risky code is written catch → handles the exception finally → always executes (cleanup code) throw → used to explicitly throw an exception throws → declares exceptions in method signature Real-World Importance📌 Exception Handling is widely used in backend systems to: Handle API failures Manage database errorsValidate user input Ensure smooth user experience Without proper exception handling, applications may crash or behave unpredictably. Understanding this concept is essential before moving into advanced topics like Multithreading, JDBC, and Spring Boot, where error handling plays a critical role. #Java #ExceptionHandling #JavaDeveloper #ProgrammingConcepts #BackendDevelopment #FullStackJourney #LearningConsistency

Java sealed classes and exhaustive pattern matching Java 17 introduced sealed classes, which allow you to explicitly list the allowed sub-types of an interface or base class. For example, here’s a toy example using a sealed interface and records (inner classes are implicitly added to the permitted sub-types if an explicit list is not given): public sealed interface SealedType { record TypeA() implements SealedType {} record TypeB() implements SealedType {} static SealedType of(String type) { return switch (type) { case “A” -> new TypeA(); case “B” -> new TypeB(); default -> throw new IllegalArgumentException(); }; } }...

🚀 Core Java Learning Journey Explored Instance, Static, and Local Variables in Java ☕ 🔹 Local Variables - Declared inside methods, constructors, or blocks - Accessible only within that specific scope - Must be initialized before use - Stored in stack memory 🔹 Instance Variables - Declared inside a class but outside methods - Belong to each object of the class - Each object has its own copy - Stored in heap memory 🔹 Static Variables - Declared using the "static" keyword - Shared among all objects of the class - Only one copy exists - Stored in method area 💡 Example: class Demo { int instanceVar = 10; // Instance variable static int staticVar = 20; // Static variable void display() { int localVar = 5; // Local variable System.out.println(localVar); } } 🎯 Key Takeaway: Understanding variable types helps in writing efficient and optimized Java programs by managing memory and scope effectively. Learning and growing at Dhee Coding Lab 💻 #Java #CoreJava #Variables #OOP #Programming #LearningJourney #FullStackDevelopment