Java Constructors: Initialization and Object Creation

📌 Is Java really an object-oriented language? This question comes up often, and the answer is more nuanced than a simple yes or no. I recently wrote an article exploring why Java is not 100% object-oriented, what “pure object orientation” actually means, and why practical languages make intentional trade-offs. Sharing the article here for anyone interested in Java, OOP concepts, or software design thinking 👇. #Java #ObjectOrientedProgramming #SoftwareEngineering #ProgrammingConcepts

While solving a competitive programming problem, I revisited an interesting concept in Java’s BigInteger class — especially the meaning of certainty in isProbablePrime(). 🔹 Problem Statement Given a number n (which can be very large), determine whether it is prime or not prime. 📌 Note: The number may contain hundreds of digits, so primitive data types (int, long) are not sufficient. 🔹 Why normal prime checking fails ❌ Traditional logic like: using for loop and finding the primenumber for (int i = 2; i <= sqrt(n); i++) does not work because: 1. int / long overflow for large inputs 2. sqrt() cannot be calculated for huge numbers 3. Time complexity becomes impractical 🔹 Correct Approach using BigInteger Java provides a built-in method:-- isProbablePrime(int certainty)--- Here, certainty means: The level of confidence that the number is prime (The probability of error is less than 1 / 2^certainty) 🔹 Java Program (Competitive-ready) import java.io.*; import java.math.BigInteger; public class Solution { public static void main(String[] args) throws Exception { BufferedReader br = new BufferedReader( new InputStreamReader(System.in)); String n = br.readLine().trim(); BigInteger number = new BigInteger(n); if (number.isProbablePrime(1)) { System.out.println("prime"); } else { System.out.println("not prime"); } } } ✔️ Handles very large numbers ✔️ Passes hidden test cases ✔️ Fast and reliable 🔹 Key Learning 💡 certainty is not the number to test It controls how confident Java should be Even certainty = 1 is sufficient for most competitive platforms 📚 Takeaway: When dealing with very large numbers, rely on BigInteger’s probabilistic algorithms instead of manual prime-checking logic. #Java #BigInteger #CompetitiveProgramming #ProblemSolving #LearningEveryDay #CodingTips

📘 Java Learning – this vs super & Constructor Chaining While strengthening my Core Java fundamentals, I learned how this and super keywords work internally and how constructor chaining ensures proper object initialization in inheritance. Here are my key learnings 👇 ✅ this Keyword this refers to the current class object. It is mainly used to: • Differentiate instance variables from local variables • Call current class constructors • Refer to current class instance methods/variables 🧪 Example: this.name = name; 📌 Resolves ambiguity between instance variable and local variable. ✅ super Keyword super refers to the immediate parent class object. It is used to: • Access parent class variables • Call parent class methods • Invoke parent class constructor 🧪 Example: super.display(); 📌 Useful when parent and child contain members with the same name. ✅ Constructor Chaining Constructor chaining means calling one constructor from another constructor. Java supports two types: ▶️ this() – Same Class Constructor Chaining • Used to call another constructor of the same class • Must be the first statement inside the constructor 🧪 Example: this(10); 📌 Avoids code duplication within the same class. ▶️ super() – Parent Class Constructor Chaining • Used to call the parent class constructor • Must be the first statement inside the constructor • If not written explicitly, Java adds super() automatically 🧪 Example: super(); 📌 Ensures parent class initialization happens before child class. ✅ Execution Order (Very Important) When an object of a child class is created: 1️⃣ Parent class constructor executes first 2️⃣ Then child class constructor executes 📌 This guarantees complete object initialization. ⚠️ Important Rules • this() and super() cannot be used together in the same constructor • Both must be the first statement • Constructor chaining prevents partial initialization ⭐ What I Gained from This • Clear understanding of object initialization flow • Strong clarity on inheritance-based constructor execution • Confidence in handling real-world Java class design • Solid foundation for: • Method overriding • Polymorphism • Runtime behavior analysis Understanding this, super, and constructor chaining is essential for writing clean, maintainable, and predictable Java applications. Building strong OOP fundamentals, one concept at a time 🚀 #Java #CoreJava #ThisKeyword #SuperKeyword #ConstructorChaining #JavaInternals #OOP #JavaFullStack #BackendDeveloper #LearningJourney

🚀 Day-60 of My 60 Days Java Challenge. 📌 Today’s Topic: Final Java Collections Revision Today isn’t about learning something new. It’s about connecting everything I’ve learned — the big picture 🧩 Initially start with : Need duplicates?  ├─ YES → List  │   ├─ Fast access → ArrayList  │   ├─ Frequent insert/delete → LinkedList  │  └─ NO → Set     ├─ No order → HashSet     ├─ Insertion order → LinkedHashSet     ├─ Sorted → TreeSet Need key-value?  ├─ Fast → HashMap  ├─ Order → LinkedHashMap  ├─ Sorted → TreeMap  ├─ Thread-safe → ConcurrentHashMap FIFO / LIFO?  ├─ Stack / Queue logic → ArrayDeque  └─ Priority-based → PriorityQueue 📌 List ArrayList → fast read LinkedList → fast insert/delete 📌 Set HashSet → unique + fast TreeSet → sorted 📌 Map HashMap → fast key access LinkedHashMap → order matters TreeMap → sorted keys 📌 Queue / Deque ArrayDeque → modern Stack + Queue 📌 Cursor Iterator → safe remove ListIterator → bidirectional entrySet() → best Map traversal 📌 Concurrency ConcurrentHashMap → thread-safe Fail-Fast ❌ vs Fail-Safe ✅ This isn’t the end —This is the foundation 🚀 🔍 Keep practicing, keep coding, and let’s inspire each other to grow stronger in programming.  💬 Got any doubts or suggestions? Feel free to share them in the comments ⬇️. ✨ This series ends here, but the learning journey continues—exciting topics ahead 🚀 #JavaCollections #CollectionsFramework #Coding #Programming #CodeEveryday #ProblemSolving #InterviewPreparation #60DaysOfCode #LearningInPublic #DeveloperJourney #BuildInPublic #ConsistentLearning #SoftwareDeveloper #BackendDeveloper #CareerGrowth #Java #CoreJava #JavaProgramming #JavaDeveloper #JavaLearning #LearnJava

🧠 Is Java’s variable a productivity boost—or a readability trap? 👉 Local Variable Type Inference — friend or foe? The post looks at: ✅ Where variable genuinely improves developer productivity ✅ When it can reduce code clarity ✅ Practical guidelines for using it responsibly in real-world Java codebases If you work with Java and care about clean, maintainable code, this is worth a look. 🔗 Blog link: https://lnkd.in/gsexkzWe #Java #JavaDev #CleanCode #CodeQuality #SoftwareEngineering #Programming #BackendDevelopment #DeveloperProductivity #TechWriting

🚀 Java Constructors — JVM Point of View 📌 In Java, constructors are special methods used to initialize objects. But what’s interesting is how the JVM handles them internally. 💡 Default Constructor (JVM Perspective) ➡️ If you do not explicitly write any constructor, the JVM automatically provides a default constructor. This default constructor initializes the object with default values (e.g., 0, null, false). ➡️ Example (no constructor written): class Student { String name; int age; } //The JVM implicitly adds: Student() { super(); } ✔ Called automatically when an object is created ✔ Calls the parent constructor (super()) 💡 Parameterized Constructor ➡️ A parameterized constructor is a constructor that accepts parameters to initialize the object with specific values. ➡️ Example: class Student { String name; int age; Student(String name, int age) { this.name = name; this.age = age; } } ✔ Used to pass data at the time of object creation ✔ Allows flexibility and avoids manual setting after creation 💡 Important JVM Rule ➡️ If you define any constructor (such as a parameterized constructor), the JVM will not generate a default constructor automatically. ➡️ Example: new Student(); // Error — no default constructor available new Student("Alex", 22); // Valid This is a key concept for those learning OOP and JVM behavior. 💡Why This Behavior Exists ➡️ The JVM assumes that if you wrote your own constructor, then you want custom initialization, so it avoids generating the default one. 💡 Quick Summary ✔ No constructor defined → JVM adds default constructor ✔ Parameterized constructor defined → JVM does NOT add default constructor ✔ Default constructor uses default values ✔ Parameterized constructor uses provided values #Java #OOP #JVM #ProgrammingFundamentals #SoftwareDevelopment #CodingBasics #Developers #ObjectOrientedProgramming #LearningJava #TechExplained

🚀 Understanding Java Object Serialization & Deserialization (with Type Information) Java is often praised for its platform independence, and one of the features that truly demonstrates this power is Object Serialization. 🔹 What is Object Serialization? Serialization is the process of converting a Java object into a stream of bytes so that it can be: Stored in a file Sent over a network Persisted for later use What makes Java serialization special is that it doesn’t store only the data, but also the type information of the object. 🔹 What does “Type Information” mean? When a Java object is serialized, the JVM stores: The class name of the object The data types of its fields The actual values of the fields This allows Java to recreate the exact same object during deserialization. 🔹 Serialization Flow 1. An object (e.g., Student) exists in memory 2. ObjectOutputStream converts the object into bytes 3. Both Object Data + Type Information are written into a .ser file 🔹 Deserialization Flow 1. The byte stream is read from the .ser file 2. ObjectInputStream uses the stored type information 3. The JVM reconstructs the original object in memory 🔹 Why is this powerful? ✔ Ensures accurate object reconstruction ✔ JVM independent (serialize on one platform, deserialize on another) ✔ Essential for distributed systems, file storage, and networking 🔹 Key Classes Involved ObjectOutputStream → Serialization ObjectInputStream → Deserialization Serializable → Marker interface that gives JVM permission 🔹 Important Insight Thread safety, execution order, or CPU scheduling is not involved here — serialization is purely about object state + structure. 📌 In short: > Java Serialization is not just about saving data, it’s about preserving the identity and structure of an object across JVM boundaries. Learning these fundamentals makes advanced topics like RMI, distributed systems, and microservices much easier to understand. #Java #Serialization #Deserialization #JVM #JavaProgramming #ComputerScience #BackendDevelopment #LearningInPublic #StudentDeveloper

📘 Java Learning – Exception Handling (Core Concepts) While strengthening my Core Java fundamentals, I learned how exception handling helps applications fail gracefully instead of crashing abruptly. Here’s a practical breakdown 👇 🚨 What is an Exception? An exception is an unwanted and unexpected event that disturbs the normal flow of a program. 🧪 Example: int x = 10 / 0; // ArithmeticException 🎯 Why Exception Handling? Exception handling does not repair the problem. It provides an alternative execution path so the program can continue or terminate properly. 📌 Main goal: Graceful termination of the program 🧠 Runtime Stack Mechanism • JVM creates a runtime stack for every thread • Each method call creates a stack frame • Stack frame contains local variables and method call information • When a method completes, its stack frame is removed • When the thread ends, the stack is destroyed 🧪 Example: void m1() { m2(); } void m2() { System.out.println(10 / 0); } 📌 Exception occurs in m2() → JVM starts stack unwinding. ⚙️ Default Exception Handling in Java When an exception occurs: 1️⃣ Exception object is created with: Exception name Description Stack trace 2️⃣ JVM checks for handling code (try-catch) 3️⃣ If not found: • Current method terminates abnormally • Stack frame is removed • JVM checks the caller method 4️⃣ If main() also doesn’t handle it: • JVM invokes Default Exception Handler 🧪 Output format: ExceptionName: description at ClassName.method(line number) ⭐ Key Takeaways • Exceptions disturb normal program flow • JVM uses runtime stack to track method calls • Default exception handling prints diagnostic details • Proper handling leads to stable and maintainable applications Building strong Java fundamentals — one exception at a time ☕🚀 #Java #CoreJava #ExceptionHandling #JVM #JavaInternals #BackendDeveloper #JavaFullStack #LearningJourney

#go #golang #oop #objectorientedprogramming 0️⃣ introduction I always thought Go is OOP, just not traditionally so. ▪️ Has interface and implicitly inherits - inheritance ▪️ Has structs and can write methods via receivers - just like methods encapsulated in a class ▪️ Can initialize an instance of a struct - constructor behavior ▪️ Can embed another struct kinda like an inherited class - a simplified version of abstraction #python doesn't have abstract class either. But it's still considered OOP language. 1️⃣ Official answer https://lnkd.in/e8akkTQb 💬 "Yes and no. Although Go has types and methods and allows an object-oriented style of programming, there is no type hierarchy. The concept of “interface” in Go provides a different approach that we believe is easy to use and in some ways more general. There are also ways to embed types in other types to provide something analogous—but not identical—to subclassing. Moreover, methods in Go are more general than in C++ or Java: they can be defined for any sort of data, even built-in types such as plain, “unboxed” integers. They are not restricted to structs (classes). Also, the lack of a type hierarchy makes “objects” in Go feel much more lightweight than in languages such as C++ or Java." 2️⃣ processing it So we can write in object oriented programming. but no class hierarchy. we have implicit inheritance but it's more of composition than inheritance. we can embed types kinda like abstract classes but they're not the same. we have methods encapsulated into a type. but the type doesn't have to be a class, so not quite. 4 pillars of OOP very much not there. the only thing we retain is that we have objects. 3️⃣ Conclusion idk. this is still very unclear to me. "Yes and no" throws me off quite a bit. It's not as nicely organized as Java or C#. but i guess thats what makes Go so flexible. #computerscience #softwareengineering #softwareengineer #swe #softwaredevelopment #softwaredeveloper #sde

📘 Java Learning – Types of Variables (Part 2: Static & Local Variables) While strengthening my Core Java fundamentals, I gained clarity on how static and local variables differ in purpose, scope, and memory behavior. Here are my key learnings 👇 ▶️ Static Variables • Used when a variable’s value does not change from object to object • Declared at class level using the static keyword • Only one shared copy exists for the entire class 📌 Any change to a static variable affects all objects. ✅ Memory & Lifecycle • Created during class loading • Destroyed during class unloading • Stored in the Method Area • Scope = class scope ✅ Access • Can be accessed using class name (recommended) • Can also be accessed using object reference • Accessible from both static and instance areas ✅ Initialization • JVM provides default values automatically ▶️ Local Variables • Declared inside methods, constructors, or blocks • Used for temporary requirements • Stored in stack memory ✅ Scope & Lifecycle • Created when the block starts execution • Destroyed when the block ends • Scope limited to the declaring block ✅ Initialization Rules • JVM does not provide default values • Must be initialized before use 📌 Best practice: initialize at the time of declaration. ✅ Modifiers • Only final is allowed • Any other modifier causes a compile-time error ⭐ What I Gained from This • Clear distinction between shared and temporary data • Better understanding of scope and memory management • Strong foundation for writing efficient Java code Understanding static and local variables is essential for building optimized and predictable Java applications. #Java #CoreJava #StaticVariables #LocalVariables #JavaInternals #JavaFullStack #LearningJourney #BackendDeveloper