Java File Handling with File Class Operations

🚀 Day 57 of My Java DSA Journey Today I worked on a classic Dynamic Programming problem: 💡 Subset Sum Problem 🧠 Approach: • Used recursion with memoization • At each step, decided whether to include or exclude an element • Stored intermediate results to optimize performance 🔍 Key Insight: A subset with sum k exists if: We can form k without current element OR We can form k - arr[i] including current element ⚡ What I learned: • DP pattern similar to Knapsack • Importance of proper memoization • Handling boolean DP states 🔥 Complexity: • Time: O(n × k) • Space: O(n × k) 🎯 Takeaway: Many DP problems are variations of a few core patterns. #Day57 #90DaysOfCoding #DSA #DynamicProgramming #Java

🚀 Day 48 of My Java Learning Journey Today, I explored one of the most important concepts in Java – Collection Framework 💡 📌 What I Learned: Collection Framework is a set of classes and interfaces used to store and manipulate data efficiently It was introduced in JDK 1.2 by Josh Bloch Acts as an alternative to Data Structures in Java 📊 Key Components: Interfaces → List, Set, Queue, Map Classes → ArrayList, LinkedList, HashSet, HashMap 🔥 Why Collections? ✔ Dynamic size (no fixed length like arrays) ✔ Inbuilt methods (add, remove, etc.) ✔ Efficient data handling ✔ Reduces coding effort 💻 Key Features: Allows heterogeneous data Maintains insertion order (List) Allows duplicates (List) Improves performance in real-world applications 📈 Takeaway: Collection Framework is a must-know concept for interviews and real-time development. Almost every Java application uses it! #Day48 #Java #CollectionsFramework #JavaDeveloper #LearningJourney #Coding #Programming

Today I strengthened my understanding of how Java programs actually execute 🚀☕ Here’s what I learned step by step: ✔ The file name must match the public class name 📄 ✔ The main() method can be inside any class, not only the public class 🔍 ✔ Only one public class is allowed in one ".java" file ⚠️ ✔ Protected members outside the package are accessible through inheritance — 🔹 Non-static → accessed using child class object 🔹 Static → accessed using child class name or parent class name inside child class 👨👦✨ ✔ The JVM first loads the class that contains main(), then loads other required classes when needed 🧠 Understanding these core execution rules is helping me build stronger clarity in Java inheritance and access modifiers 💻📚 #Java #Programming #LearningJourney #OOP #JavaDeveloper #BackendDevelopment 🚀

Day 21– Thread Methods in Java Today I explored how to control threads in Java using different methods. Things I learned: 🔹 start() – begins thread execution 🔹 run() – contains logic (called internally) 🔹 sleep() – pauses thread for a specific time 🔹 join() – ensures one thread finishes before another starts 💡 Key takeaway: Thread methods help manage execution flow and improve control over multithreading behavior. Step by step understanding how Java handles concurrent tasks 🚀 #Java #Multithreading #Threads #Programming #LearningInPublic #Day21 #100DaysOfJava

Multithreading in Java finally clicked for me when I stopped memorizing it… and started visualizing it. 🧠 Here’s the simplest way to understand it: Imagine your application is doing only ONE task at a time. ➡️ Slow ➡️ Blocking ➡️ Poor performance Now introduce multithreading 👇 Multiple tasks run simultaneously: ✔ One thread handles API requests ✔ One processes data ✔ One writes logs Result? Faster and more efficient applications 🚀 But here’s what I learned the hard way: Multithreading is powerful… but dangerous if not handled properly. Common issues I faced: Race conditions Deadlocks Unexpected bugs What helped me: ✔ Proper synchronization ✔ Understanding thread lifecycle ✔ Using ExecutorService instead of manual threads Lesson: Multithreading is not just about speed — it’s about control and correctness. 💬 Have you faced any tricky bugs with multithreading? #Java #Multithreading #BackendDevelopment #SoftwareEngineering #Coding

Day 89 of #100DaysOfLeetCode 💻✅ Solved #15. 3Sum problem in Java. Approach: • Sorted the array first • Fixed one element and used Two Pointers for the rest • Skipped duplicates to avoid repeated triplets • Adjusted pointers based on sum comparison Performance: ✓ Runtime: 30 ms (Beats 87.77% submissions) ✓ Memory: 59.02 MB (Beats 77.30% submissions) Key Learning: ✓ Mastered Two Pointer technique with sorting ✓ Learned handling duplicates efficiently ✓ Improved problem-solving for combination-based problems Learning one problem every single day 🚀 #Java #LeetCode #DSA #TwoPointers #Arrays #Sorting #ProblemSolving #CodingJourney #100DaysOfCode

Day 24 – String Methods in Java Today I explored commonly used String methods in Java, which are essential for handling text data. Things I learned: 🔹 length() – finds string length 🔹 charAt() – accesses characters 🔹 substring() – extracts part of string 🔹 equals() – compares values 🔹 Case conversion methods 💡 Key takeaway: String methods are widely used in real-world applications for processing and manipulating text efficiently. Building stronger fundamentals step by step #Java #Strings #Programming #LearningInPublic #CodingJourney #Day24 #100DaysOfJava

Day 52-What I Learned In a Day (JAVA) Today I learned some fundamental concepts in Java related to objects and methods. 🔹 Creating Objects (for Non-Static Methods) Understood that to access non-static methods, we must create an object of the class. 🔹 Steps to Create an Object 1️⃣ Declare reference variable 2️⃣ Create object using new keyword 3️⃣ Assign it to the reference 🔹 new Keyword Learned that it is used to allocate memory in the heap and create an object. 🔹 Non-Primitive Data Types Explored how objects, arrays, and classes store references instead of actual values. 🔹 Accessing Data from Another Class Learned how to access variables and methods from another class by creating an object of that class and using the reference. These concepts helped me understand how Java objects work, how memory is managed, and how classes interact with each other. #Java #OOP #Programming #LearningJourney #Coding #100DaysOfCode

💻 Day 23 – Strings in Java Today I explored Strings in Java, one of the most fundamental and important concepts. I learned about different types of string handling: 🔹 String – Immutable (cannot be changed) 🔹 StringBuilder – Mutable and faster 🔹 StringBuffer – Mutable and thread-safe Understanding immutability was a key highlight today, as it plays an important role in memory management and performance. 💡 Key takeaway: Choosing the right type of string handling improves both performance and efficiency in Java applications. Continuing to strengthen my core Java concepts step by step 🚀 #Java #Strings #Programming #LearningInPublic #CodingJourney #Day23

Day 55-What I Learned In a Day (JAVA) Today, I learned how to create and use constructors in Java. 🔹 A constructor is a special method used to initialize an object when it is created. 🔹 Constructors are non-static by default, meaning they work with objects and help assign values to instance variables. 🔹 They are automatically executed when an object is created, making object initialization simple and efficient. 🔹 This reduces the need for setting values manually after object creation. Understanding constructors helped me see how Java initializes objects in a structured and efficient way. #Java #OOP #Constructors #LearningJourney #Programming #TechSkills