Java Immutable Class: Thread-Safe & Easier to Reason About

How to add all elements of an array in Java (Explained simply) Imagine you’re sitting in front of me and you ask: 👉 “How do I add all the numbers present in an array using Java?” I’d explain it like this 👇 Think of an array as a box that already contains some numbers. For example: [2, 4, 6, 8] Now our goal is simple: ➡️ Take each number one by one ➡️ Keep adding it to a total sum Step-by-step thinking: First, we create a variable called sum and set it to 0 (because before adding anything, the total is zero) Then we loop through the array Each time we see a number, we add it to sum After the loop finishes, sum will contain the final answer Java Code: int[] arr = {2, 4, 6, 8}; int sum = 0; for (int i = 0; i < arr.length; i++) { sum = sum + arr[i]; } System.out.println(sum); What’s happening here? arr[i] → current element of the array sum = sum + arr[i] → keep adding elements one by one Loop runs till the last element Final Output: 20 One-line explanation: “We start from zero and keep adding each element of the array until nothing is left.” If you understand this logic, you’ve already learned: ✔ loops ✔ arrays ✔ problem-solving mindset This is the foundation of many real-world problems in Java 🚀 #Java #Programming #DSA #BeginnerFriendly #LearnJava #CodingBasics

Day 15 Try-with-Resources Try-with-resources is a Java language construct (introduced in Java 7) that automatically closes resources such as files, streams, database connections, and sockets once the try block completes. It eliminates the need for explicit finally blocks to release resources. Before Java 7, developers had to manually close resources in a finally block, which was: Verbose Error-prone Susceptible to resource leaks if exceptions occurred Try-with-resources ensures deterministic resource cleanup. Key Requirement: Any resource used in try-with-resources must implement AutoCloseable (or Closeable). Examples: FileInputStream BufferedReader Connection PreparedStatement ResultSet #Java #Trywithresourse #JavaCollections #InterviewPreparation #CoreJava #DataStructures #SoftwareEngineering #JavaDeveloper #CodingInterview #LinkedInLearning #Javalnterview #Programming #BackendDeveloper #SoftwareEngineering #LearnJava #DailyJava #ITCareers #TechLearning #Coding #DeveloperLife #JavaCommunity

🔹 What is a String? In Java, a String is an object that represents a sequence of characters enclosed in double quotes (" "). Strings are immutable, meaning their value cannot be changed once created, and they use UTF-16 encoding internally. 🔹 Types of Strings Java provides different types of classes to work with strings based on mutability and thread-safety: String – Immutable and thread-safe. StringBuffer – Mutable and thread-safe; suitable for multi-threaded environments. StringBuilder – Mutable and not thread-safe; ideal for single-threaded programs. 🔹 Why We Use Strings Strings are essential for handling text data in applications: User input and output Authentication and authorization (username/password) API requests and responses Logging and messaging File and data processing 🔹 Advantages of Strings Immutable → ensures data integrity and security Thread-safe → safe in concurrent programs Memory-efficient → uses String Constant Pool for literals Rich API → provides powerful built-in methods for manipulation #Java #CoreJava #StringsInJava #JavaBasics #Programming #LinkedInLearning #JavaInterview

🔐 Java Access Modifiers Access modifiers in Java define where a class, method, or variable can be accessed, and they play a crucial role in encapsulation, security, and clean code design. In this visual, I’ve summarized all four access modifiers with clear rules and examples: 🔹 public – Accessible from anywhere (same class, same package, subclasses, and other packages). 🔹 protected – Accessible within the same package and by subclasses (supports inheritance). 🔹 default (package-private) – Accessible only within the same package. 🔹 private – Accessible only inside the same class (maximum data hiding). Each section includes: ✔ Access scope ✔ When to use it ✔ Simple Java code examples ✔ A comparison table for quick revision Understanding access modifiers is essential for writing secure, maintainable, and interview-ready Java applications. Strong fundamentals always lead to better design decisions. 🚀 #Java #CoreJava #OOPs #AccessModifiers #JavaLearning #ProgrammingConcepts #DeveloperJourney #LearningInPublic

Day 1 – Strengthening Core Java Problem Solving Today I practiced six conditional-logic problems in Java to improve clarity of thought and real-world decision making in code. Sharing one of them below — finding the roots of a quadratic equation using the discriminant (b² – 4ac). Key learnings: Used the discriminant to determine real, equal, or imaginary roots Applied an if–else–if chain to handle all possible cases cleanly Understood how mathematical logic translates directly into Java code Problem-solving reminder to myself: Good code comes from clear logic, not long syntax. I’ll share the remaining five problems in the comments for anyone who wants to explore the logic behind them. Thanks @Prasoon Bidua Sir for the guidance and emphasis on understanding fundamentals through practice. #Java #CoreJava #LearningInPublic #ConditionalStatements

Immutable class in Java: What is immutable class? Its a class whose instances cannot be changed after creation. How to create an immutable class? 1️⃣declare class as `final` - Prevents other classes from extend it 2️⃣ declare fields as `private` and `final` - `private` prevents the fields cannot be accessed outside of the class; `final` assures the value will be set only once 3️⃣ no setter methods - Prevents overriding the values 4️⃣ constructor initialisation - Initialises all the fields in the all arguments consructor Here are some of the ways to create an immutable class(refer the image). 1️⃣ Using plain Java 2️⃣ Using lombok library - lombok provides `Value` annotation to create immutable class with minimal code 3️⃣ Using records - `public record User(int id, String name){}` Reference: https://lnkd.in/ghDmd4Ww Note: Lombok doesn't convert a collections like List, Set or Map to immutable internally. Make sure you're passing an immutable collections to the constructor. `Arrays.asList`, Factories like `List.of`, `Set.of`, and `Map.of` return immutable collection. `java.util.Collections` provides utility methods to convert the mutable connections to immutable. #java #lombok #immutable #LearnJava #programming

🔹 What is a Method? A method in Java is a reusable block of code that performs a specific task and improves code structure, readability, and maintainability. returnType methodName(parameters) { // logic } 🧠 Types of Methods in Java 🔹 Predefined Methods Built-in methods provided by Java Examples: println(), length(), nextInt() 🔹 User-Defined Methods Custom methods written by the programmer 🔹 Static Methods • Belong to the class • No object required • Example: main() 🔹 Instance Methods • Belong to objects • Called using object reference 🔹 Methods with Parameters • Accept input values 🔹 Methods with Return Type • Return results to the caller 🔹 Void Methods • Perform actions but return nothing #Java #MethodsInJava #CleanCode #OOP #Programming #SoftwareEngineering #JavaDeveloper #LearnJava

In continuation of my previous post on Virtual Threads. Creating virtual threads is very straightforward in Java. We don’t need to manage thread pools or worry about how many threads we are creating. We can create a virtual thread directly using: Thread thread = Thread.startVirtualThread(() -> { /* some task */ }); Or by using an executor service: ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor(); executor.submit(() -> { /* some task */ }); If you run this example, you may never see the output of your thread. Your program may finish execution even before the thread prints anything. This happens because virtual threads are “daemon threads” and the main thread does not wait for daemon threads to finish execution. To prevent the JVM from exiting before the virtual threads complete, you can do: thread.join(); Or, Use try-with-resources when using an executor service, because closing the executor waits for all submitted tasks to finish. How do you manage virtual threads let me know in the comments!

🚀 LeetCode Solution: Intersection of Two Linked Lists (Java) 🔗 I solved the “Intersection of Two Linked Lists” problem using an efficient two-pointer approach in Java 💡 🧩 Problem Goal Find the node where two singly linked lists intersect. ✔ Do not modify the lists ✔ Use constant extra space ⚙️ Code Logic Explained 👉 First, we check if either list is null. If yes, intersection is impossible ❌ 👉 Two pointers t1 and t2 start at the heads of both lists When t1 reaches the end, it jumps to headB When t2 reaches the end, it jumps to headA 🔁 This balances the traversal length of both lists 📍 If an intersection exists, both pointers meet at the same node 📍 If not, both pointers become null ⏱ Complexity ✅ Time Complexity: O(m + n) ✅ Space Complexity: O(1) 🎯 Key Takeaway This problem is a great example of how smart pointer manipulation can eliminate the need for extra memory and simplify complex logic 🔥 Excited to keep improving my DSA & Java problem-solving skills 💻✨ #LeetCode #Java #LinkedList #DSA #TwoPointers #ProblemSolving #CodingJourney 🚀

🔹 Java Program: Odd or Even Number Checker This Java program is designed to determine whether a given number is odd or even using simple conditional logic. 🔹 How the Program Works: The program uses the Scanner class to take input from the user. An integer value is stored in a variable. Using the modulus operator (%), the program checks the remainder when the number is divided by 2. If the remainder is 0, the number is even. Otherwise, the number is odd. Based on this condition, the appropriate message is printed to the console. 🔹 Key Concepts Used: Scanner for user input if-else conditional statement Modulus operator (%) Basic input/output operations 🔹 Output: Displays “is the even number” if the number is even Displays “is the odd number” if the number is odd This program is a great example of understanding basic Java syntax, conditional logic, and user input handling. Perfect for beginners who are learning Java fundamentals 🚀 #Java #JavaProgramming #CodingBasics #LearningJava #StudentDeveloper #Programming