Java Practice Questions and Answers on GitHub

I have started contributing on this repository which focuses on topic-wise Java questions and solutions. As of now, the topics included are Arrays, OOPS, Sorting, Strings and StringBuilders. The topics will be further segregated into basic, intermediate and advanced questions. This is going to be beneficial for Java-learners and at the same time this will give me a scope to learn more and analyse while solving the problems. I sincerely hope to explore different approaches and strengthen my own logic and understanding. Do drop your suggestions and feedback, those would be really helpful. Repository link: https://lnkd.in/dv4MNNAA #Java #Programming #Beginners #Learning

🚀 Day 16 of My Java Learning Journey Today, I explored one of the most important OOP concepts in Java — Constructors 🔥 🔹 What I Learned: • Constructor is a special method used to initialize objects • It has the same name as the class • No return type (not even void) • Automatically called when object is created 🔹 Types of Constructors: • Default Constructor • Parameterized Constructor 💡 Key Insight: Java does not have a built-in copy constructor like C++, but we can create it manually if needed. 🧠 Realization: Constructors make object creation more structured and efficient — they are like the “starting point” of any object in Java. Consistency + Practice = Growth my mentor Aman Soni Vidhya Code Gurukul #Java #OOP #Programming #LearningJourney #CodeNewbie #100DaysOfCode #Developers #TechSkills

🚀 Understanding the Rules of Inheritance in Java – Simplified! Inheritance is one of the core pillars of Object-Oriented Programming, but not everything gets inherited ⚠️ In this infographic, I’ve clearly explained two important rules: 🔒 Private Members do NOT participate in inheritance – to protect encapsulation and ensure data security within the class. 🏗️ Constructors do NOT participate in inheritance – because constructor naming rules must match the class name, which cannot be inherited. To make it even more practical, I’ve also included: 📊 Differences between this.callMethod() and super.callMethod() 📊 Comparison of this keyword vs super keyword 📊 Difference between super keyword and super method call This visual guide helps you quickly understand what is inherited, what is not, and why it matters in real-world Java programming 💡 Perfect for students, interview prep, and strengthening core OOP concepts 🔥 💬 Which concept helped you the most—this or super? #Java #OOP #Inheritance #Programming #Coding #JavaDeveloper #SoftwareDevelopment #LearnJava #TechConcepts #ComputerScience #CodingLife #Developers #InterviewPrep #ProgrammingBasics TAP Academy

🚀 Day 1 of Teaching Java in Public | #30DaysOfJava Today, I started with the fundamentals of Java and created structured notes to make it easier for beginners to understand. ☕ 📌 What is Java? Java is a high-level, class-based, object-oriented programming language designed to be platform-independent. 💡 Key Highlights: ✔ Write Once, Run Anywhere (WORA) ✔ Powered by JVM (Java Virtual Machine) ✔ Secure, Robust, and Multithreaded 📘 What I Covered Today: 🔹 Introduction to Java 🔹 Basic Syntax (Hello World Program) 🔹 Overview of OOP Concepts 🔹 Data Types & Variables 🔹 Operators & Control Statements 🔹 Arrays, Methods, Classes & Objects 🧠 Teaching Insight: When concepts are organized visually (like in the notes below), learning becomes faster and more effective. 👉 If you're starting Java, this is all you need for Day 1. I’ll be sharing simplified Java concepts daily — follow along if you're learning too! 🙌 #Java #Teaching #LearnInPublic #CodingJourney #Developers #Beginners #Programming

🚀 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 2 of Java Learning Series 🔹 Understanding OOP Concepts in Java Java is based on Object-Oriented Programming (OOP), which helps in writing clean, reusable, and scalable code. 🔑 4 Main OOP Concepts: 1️⃣ Encapsulation 👉 Wrapping data (variables) and code (methods) into a single unit 👉 Achieved using classes 👉 Helps in data hiding 💡 Example: class Student { private String name; public void setName(String name) { this.name = name; } public String getName() { return name; } } 2️⃣ Inheritance 👉 One class can inherit properties of another class 👉 Promotes code reuse 💡 Example: class Animal { void sound() { System.out.println("Animal makes sound"); } } class Dog extends Animal { void bark() { System.out.println("Dog barks"); } } 3️⃣ Polymorphism 👉 One action, many forms 👉 Method overloading & overriding 4️⃣ Abstraction 👉 Hiding implementation details and showing only functionality 👉 Achieved using abstract classes & interfaces 🚀 Mastering OOP is the foundation of becoming a strong Java developer! 👉 Follow for more Java concepts #Java #OOP #Programming #Developers #Learning #100DaysOfCode

🚀 Starting My Java Learning Journey – Day 16 🔹 Topic: Encapsulation in Java. Encapsulation is one of the core OOP concepts. It is the process of wrapping data (variables) and code (methods) into a single unit (class). It also helps in data hiding. 📌 How to Achieve Encapsulation? ✔ Declare variables as private. ✔ Provide public getter and setter methods to access and update values. 📌 Example Program class Student { private String name; // Getter method public String getName() { return name; } // Setter method public void setName(String name) { this.name = name; } } public class Main { public static void main(String[] args) { Student s1 = new Student(); s1.setName("John"); System.out.println(s1.getName()); } } Output: John 💡 Key Points: ✔ Protects data from unauthorized access. ✔ Improves security and flexibility. ✔ Achieved using private variables + getters/setters. #Java#JavaLearning #Programming #BackendDevelopment #CodingJourney #Encapsulation #OOP#

🔐 Access Modifiers in Java – Mastering Visibility & Control! Ever wondered how Java controls who can access what in your code? 🤔 That’s where Access Modifiers come into play! In this infographic, I’ve broken down the 4 key access modifiers in Java: 🌍 public – Accessible from anywhere (most flexible) 🛡️ protected – Accessible within the same class, package, and even subclasses in different packages 📦 package (default) – Accessible only within the same package 🔒 private – Accessible only within the same class (most restricted) 📊 Includes a clear comparison table to quickly understand accessibility across: ✔ Same Class ✔ Subclass (Same Package) ✔ Subclass (Different Package) ✔ Other Classes (Different Package) 💻 Plus, a practical code example to connect theory with real-world Java usage! This guide is perfect for building strong OOP fundamentals and writing secure, well-structured code 🔥 💬 Which access modifier do you use the most in your projects? #Java #OOP #AccessModifiers #Programming #Coding #JavaDeveloper #LearnJava #SoftwareDevelopment #CodingLife #Developers #TechEducation #ComputerScience #ProgrammingConcepts #CodeBetter TAP Academy

🔐 Access Modifiers in Java – Mastering Visibility & Control! Ever wondered how Java controls who can access what in your code? 🤔 That’s where Access Modifiers come into play! In this infographic, I’ve broken down the 4 key access modifiers in Java: 🌍 public – Accessible from anywhere (most flexible) 🛡️ protected – Accessible within the same class, package, and even subclasses in different packages 📦 package (default) – Accessible only within the same package 🔒 private – Accessible only within the same class (most restricted) 📊 Includes a clear comparison table to quickly understand accessibility across: ✔ Same Class ✔ Subclass (Same Package) ✔ Subclass (Different Package) ✔ Other Classes (Different Package) 💻 Plus, a practical code example to connect theory with real-world Java usage! This guide is perfect for building strong OOP fundamentals and writing secure, well-structured code 🔥 💬 Which access modifier do you use the most in your projects? #Java #OOP #AccessModifiers #Programming #Coding #JavaDeveloper #LearnJava #SoftwareDevelopment #CodingLife #Developers #TechEducation #ComputerScience #ProgrammingConcepts #CodeBetter TAP Academy

While continuing my Java learning, I recently explored one of the most important concepts in programming — Methods. This helped me understand how to write cleaner, reusable, and more structured code. Here are some key learnings from this topic: ✨ Key Learnings – Java Methods • ⚙️ Methods – Blocks of code that perform a specific task and can be reused multiple times • 📥 Method Parameters – Inputs passed to a method, allowing dynamic and flexible execution • 📤 Return Values – Methods can return results using the "return" keyword, making them useful for computations • 🔁 Code Reusability – Methods help avoid repetition and make programs more organized • 🧩 Better Structure – Breaking programs into smaller methods improves readability and maintainability • 🔄 Recursion – A method calling itself to solve a problem step by step • 🎯 Base Condition in Recursion – Ensures the method stops at the right time and avoids infinite loop. #Java #Programming #LearningJourney #SoftwareDevelopment #StudentDeveloper #W3Schools