Java String Concatenation & concat() Method Explained

Day 41 of Learning Java: Method Overriding If method overloading was about flexibility,method overriding is about customization. What is Method Overriding? It’s when a subclass provides its own implementation of a method that is already defined in the parent class. Same method name. Same parameters. But different behavior. 🔹 Simple example- class Parent { void watchTV() { System.out.println("Watching News/Serial"); } } class Child extends Parent { @Override void watchTV() { System.out.println("Watching Music/Sports"); } } Same method → different output depending on the object. • Parent defines a general behavior • Child modifies it based on its own need • This helps in writing more flexible and reusable code 🔹 Key points to remember • Method signature must be the same • Happens during runtime (runtime polymorphism) • Inheritance is required 👉 You cannot override: static methods private methods final methods 🔹 One important concept Parent ref = new Child(); ref.watchTV(); Even though the reference is of Parent, the method of Child gets executed. 👉 This is called dynamic method dispatch 🔹 About @Override It’s not mandatory, but it helps: ✔ Avoid mistakes ✔ Makes code more readable ✔ Ensures you’re actually overriding #Java #OOP #MethodOverriding #LearningInPublic #Programming#sql #branding

🚀 Learning Core Java – Understanding Method Overriding Today I explored an important concept in Java — Method Overriding. Method overriding occurs when a child class provides its own implementation of a method that is already defined in the parent class. It is mainly used to achieve runtime polymorphism, which is also known as: 👉 Late Binding 👉 Dynamic Binding 👉 True Polymorphism 🔹 Rules for Method Overriding To correctly override a method in Java, we must follow these rules: ✔ Method Name & Parameters The method name and parameters must be exactly the same as in the parent class. ✔ Access Modifiers The access level of the overridden method should be: 👉 Same or more accessible (increased visibility) Example: protected → public ✅ public → protected ❌ ✔ Return Type Before JDK 5 → Return type must be exactly the same After JDK 5 → Can be same or covariant return type ✔ Parameters Parameters must remain unchanged (same type, number, and order) 🔎 What is Covariant Return Type? It means the overridden method can return a subclass type instead of the parent type, providing more flexibility. 💡 Key Insight Method overriding enables: ✔ Runtime polymorphism (dynamic behavior) ✔ Flexible and extensible design ✔ Cleaner and maintainable code Understanding overriding is essential for building scalable and robust object-oriented applications. Excited to keep strengthening my Java fundamentals! 🚀 #CoreJava #MethodOverriding #Polymorphism #RuntimePolymorphism #JavaDeveloper #ProgrammingFundamentals #LearningJourney #SoftwareEngineering

📚 Day 20 at Tap Academy – Learning Strings in Java Today I learned about Strings in Java, a fundamental concept used in almost every program. 🔹 What is a String? A String is a collection of characters enclosed within double quotes (" "). In Java, Strings are objects, not primitive data types. 🔹 Types of Strings ✔️ Immutable Strings - Cannot be changed once created - Example: Name, Gender, DOB ✔️ Mutable Strings - Can be modified after creation - Example: Email ID, Password 🔹 Memory Concept - Strings created using literals are stored in the String Constant Pool (SCP) - Strings created using "new" keyword are stored in Heap Memory 🔹 Ways to Create Strings String s1 = "JAVA"; String s2 = new String("JAVA"); char[] ch = {'J','A','V','A'}; String s3 = new String(ch); 🔹 String Comparison ✔️ "==" → compares reference ✔️ ".equals()" → compares values String a = "Hello"; String b = "Hello"; System.out.println(a == b); // true System.out.println(a.equals(b)); // true 💡 Key Takeaway: Strings are powerful in Java, and understanding how they work helps in writing efficient and optimized code. #Java #Programming #Coding #JavaDeveloper #LearningJourney #TapAcademy #Day20

Day 40 of Learning Java: Method Overloading Instead of creating different method names for similar tasks, we can use the same method name but change the parameters — and Java figures out which one to call. -So what exactly is Method Overloading? It’s when multiple methods in the same class have: ✔ Same name ✔ Different parameter list That’s it. Simple idea, but very powerful. -Ways to overload a method • Change the type of parameters • Change the number of parameters • Change the order of parameters Example- Think of a login system: Login using username + password Login using mobile + password Both are login actions, right? So instead of writing different method names, we just overload: login(String username, String password) login(long mobile, String password) Same method name → different ways to use it -Another relatable one Payment systems 👇 COD UPI Card Net Banking Instead of: paymentByUPI(), paymentByCard()… We can just do: payment() payment(String upi) payment(long card) payment(String user, String pass) - Important things I learned • Just changing return type won’t work (it gives error) • Overloading happens at compile time • Works with static, private, and even final methods • Yes, even main() can be overloaded (but JVM only runs the standard one) #Java #LearningInPublic #100DaysOfCode #Programming #OOP #CodingJourney

🚀 Day 23 of Learning Java @ Tap Academy 📘 Mutable Strings in Java Today, I learned about mutable strings—strings whose values can be changed after creation. 🔹 Classes used: ✔️ StringBuffer ✔️ StringBuilder These classes are used to create modifiable (mutable) strings in Java. 🔹 StringBuffer Basics: ✔️ Default capacity is 16 ✔️ Used to create mutable strings Example: StringBuffer sb = new StringBuffer(); sb.append("Hello"); System.out.println(sb); 🔹 Important Methods: ✔️ append(String s) → Adds text to the end ✔️ length() → Returns length of string ✔️ capacity() → Returns current capacity ✔️ ensureCapacity(n) → Increases capacity 📌 Capacity formula: New Capacity = (old capacity × 2) + 2 🔹 StringTokenizer: Used to split a string into tokens. Example: String s = "Java Python SQL AI"; StringTokenizer st = new StringTokenizer(s, " "); while(st.hasMoreTokens()) { System.out.println(st.nextToken()); } 💡 Key Takeaway: Mutable strings are efficient when frequent modifications are required. #TapAcademy #Java #LearningJava #Day23 #CodingJourney #JavaBasics #100DaysOfCode

🚀 I’ve just published my Java Day 3 article — and today’s learning was more about understanding how Java thinks than just writing code. When I started, I thought programming is only about printing output and running programs. But today I learned something different: 👉 Some words in Java are special (keywords) — you can’t just use them anywhere 👉 Some values should never change (constants using final) 👉 And sometimes data needs to change its type to make things work (type conversion) Honestly, at first these topics sounded boring and too “theory-like”. But once I tried them in code, I realized how important they are for writing clean and safe programs. Day by day, Java is feeling: ✔ Less scary ✔ More logical ✔ More interesting From “Hello World” to actually understanding how data works inside Java — this journey already feels worth it. #Java #LearningInPublic #BCA #BeginnerDeveloper #CodingJourney #LearnJava #StudentLife #Programming #Day3 #Java

🚀 Core Java Learning Journey Explored Constructors in Java and the rules for writing them ☕ 🔹 What is a Constructor? A constructor is a special method used to initialize objects. It is automatically called when an object is created. 📌 Key Features of Constructors: ✅ Same name as the class ✅ No return type (not even "void") ✅ Automatically invoked during object creation ✅ Used to initialize instance variables 🔹 Types of Constructors: ✔️ Default Constructor ✔️ Parameterized Constructor 📌 Rules for Writing Constructors: 🔸 Constructor name must be the same as the class name 🔸 It should not have any return type 🔸 Can be overloaded (multiple constructors in one class) 🔸 Cannot be static, final, or abstract 🔸 If no constructor is written, Java provides a default constructor 💡 Example: class Student { int id; String name; Student(int i, String n) { // Parameterized constructor id = i; name = n; } } 🎯 Key Takeaway: Constructors make object initialization easy and are a fundamental part of Object-Oriented Programming in Java. Learning and growing at Dhee Coding Lab 💻 #Java #CoreJava #Constructors #OOP #Programming #LearningJourney #FullStackDevelopment

DAY 29: CORE JAVA 🔗 Constructor Chaining in Java using "super()" (Inheritance) While learning Java OOP concepts, one interesting topic I explored is Constructor Chaining in Inheritance. 📌 What is Constructor Chaining? Constructor chaining is the process of calling one constructor from another constructor. In inheritance, a child class constructor calls the parent class constructor using "super()". This ensures that the parent class variables are initialized before the child class variables. ⚙️ Key Points to Remember • "super()" is used to call the parent class constructor. • It must be the first statement inside the child constructor. • If we don’t explicitly write "super()", Java automatically calls the parent class default constructor. • This mechanism ensures proper initialization of objects in inheritance hierarchy. 💡 Example Scenario Parent Class: class Test1 { int x = 100; int y = 200; } Child Class: class Test2 extends Test1 { int a = 300; int b = 400; } When an object of "Test2" is created, Java first calls the parent constructor, initializes "x" and "y", and then initializes "a" and "b". 📊 Execution Flow 1️⃣ Object of child class is created 2️⃣ Child constructor calls "super()" 3️⃣ Parent constructor executes first 4️⃣ Control returns to child constructor This concept is very important for understanding object initialization, inheritance hierarchy, and memory allocation in Java. 🚀 Learning these small internal mechanisms of Java helps build a strong foundation in Object-Oriented Programming. TAP Academy #Java #OOP #ConstructorChaining #Inheritance #JavaProgramming #SoftwareDevelopment #CodingJourney

--->> Understanding Inheritance in Java & Its Types **Inheritance is a fundamental concept in Object-Oriented Programming (OOP) that allows one class to acquire the properties and behaviors of another class. √ What is Inheritance? It is the process where a child class inherits variables and methods from a parent class using the extends keyword. ~Why is it Important? ✔️ Code reusability ✔️ Reduced development time ✔️ Better maintainability ✔️ Cleaner and scalable design @ Types of Inheritance in Java 1️⃣ Single Inheritance 2️⃣ Multilevel Inheritance 3️⃣ Hierarchical Inheritance 4️⃣ Hybrid (combination of types) # Important Notes 🔸 Java does NOT support multiple inheritance using classes ➡️ Because of the Diamond Problem (ambiguity in method resolution) 🔸 Cyclic inheritance is not allowed ➡️ Prevents infinite loops in class relationships 💻 Code Example (Single Inheritance) Java class Parent { void show() { System.out.println("This is Parent class"); } } class Child extends Parent { void display() { System.out.println("This is Child class"); } } public class Main { public static void main(String[] args) { Child obj = new Child(); obj.show(); // inherited method obj.display(); // child method } } 👉 Here, the Child class inherits the show() method from the Parent class. -->> Real-World Example Think of a Vehicle system 🚗 Parent: Vehicle Child: Car, Bike All vehicles share common features like speed and fuel, but each has its own unique behavior. @ Key Takeaway Inheritance helps you avoid code duplication and build efficient, reusable, and scalable application TAP Academy #Java #OOP #Inheritance #Programming #JavaDeveloper #Coding #SoftwareDevelopment #LearnJava

🚀 Understanding Constructors in Java – With Examples Today, I explored Constructors in Java, one of the most important concepts in Object-Oriented Programming. 🔹 A constructor is a special method that gets called automatically when an object is created. It helps initialize the object with the required values. 💡 Types of Constructors I learned: ✔ Default Constructor class Student { String name; Student() { name = "Default"; } } ✔ Parameterized Constructor class Student { String name; Student(String n) { name = n; } } ✔ Constructor Overloading class Student { Student() { System.out.println("Default"); } Student(int id) { System.out.println("ID: " + id); } } ✔ Constructor Chaining class Student { Student() { this(100); System.out.println("Default Constructor"); } Student(int id) { System.out.println("Parameterized: " + id); } } 📌 Why Constructors matter? 🔐 Ensures proper object initialization 🧱 Makes code clean and structured 🔄 Avoids repetition using chaining 👉 One key takeaway: Constructors make object creation meaningful and organized. Step by step, building strong Java fundamentals 🚀 What Java concept are you currently learning? #Java #OOPS #Constructors #Code #Programming #LearningJourney #Developers #tapacademy