Lombok's @SneakyThrows: Java Exception Handling

Day 37 - 🚀 Rules of Method Overriding in Java Method Overriding is a key concept in Object-Oriented Programming (OOP) that allows a subclass to provide a specific implementation of a method already defined in its superclass. It helps achieve Runtime Polymorphism in Java. 📌 Important Rules of Method Overriding: 🔹 1. Same Method Name The method in the subclass must have the same name as in the superclass. 🔹 2. Same Method Parameters The number, type, and order of parameters must be exactly the same. 🔹 3. Return Type The return type must be the same or a covariant type (subtype) of the parent method. 🔹 4. Access Modifier Rule The subclass method cannot reduce visibility. Example: ✔ protected → public ✔ default → protected ❌ public → private 🔹 5. Final Methods Cannot Be Overridden If a method is declared final, it cannot be overridden. 🔹 6. Static Methods Cannot Be Overridden Static methods belong to the class and are method hidden, not overridden. 🔹 7. Private Methods Cannot Be Overridden Private methods are not inherited, so they cannot be overridden. 🔹 8. Exception Handling Rule The child class method cannot throw broader checked exceptions than the parent method. 🔹 9. Use @Override Annotation Using @Override helps the compiler check whether the method is correctly overridden. 💡 Conclusion: Method Overriding enables runtime polymorphism, making Java programs more flexible, maintainable, and scalable. #Java #OOP #MethodOverriding #JavaProgramming #ProgrammingConcepts #SoftwareDevelopment

Generic Classes in Java – Clean Explanation with Examples 🚀 Generics in Java are a compile-time type-safety mechanism that allows you to write parameterized classes, methods, and interfaces. Instead of hardcoding a type, you define a type placeholder (like T) that gets replaced with an actual type during usage. 🔹Before Generics (Problem): class Box { Object value; } Box box = new Box(); box.value = "Hello"; Integer x = (Integer) box.value; // Runtime error ❌ Issues: • No type safety • Manual casting required • Errors occur at runtime 🔹With Generics (Solution): class Box<T> { private T value; public void set(T value) { this.value = value; } public T get() { return value; } } 🔹Usage: public class Main { public static void main(String[] args) { Box<Integer> intBox = new Box<>(); intBox.set(10); int num = intBox.get(); // ✅ No casting Box<String> strBox = new Box<>(); strBox.set("Hello"); String text = strBox.get(); } } 🔹Bounded Generics: 1.Upper Bound (extends) → Read Only:  Restricts type to a subclass List<? extends Number> list; ✔ Allowed: Integer, Double ❌ Not Allowed: String 👉 Why Read Only? You can safely read values as Number, but you cannot add specific types because the exact subtype is unknown at compile time. 2.Lower Bound (super) → Write Only: Restricts type to a superclass List<? super Integer> list; ✔ Allowed: Integer, Number, Object ❌ Not Allowed: Double, String 👉 Why Write Only? You can safely add Integer (or its subclasses), but when reading, you only get Object since the exact type is unknown. 🔹Key Takeaway: Generics = Type Safety + No Casting + Compile-Time Errors Clean code, fewer bugs, and better maintainability - that’s the power of Generics 💡 #Java #Generics #Programming #SoftwareEngineering #Coding

Day 22 – Reference Variables in Java Today I explored an important concept in Object-Oriented Programming — Reference Variables. Unlike primitive variables, reference variables store the address of an object, not the actual value. 🔹 What is a Reference Variable? A reference variable is a non-primitive variable that refers to an object created from a class. It is declared using the class name. Syntax: ClassName referenceVariable; Initialization- referenceVariable = new ClassName(); Or both together: ClassName referenceVariable = new ClassName(); Here: ClassName → Name of the class referenceVariable → Object reference new → Keyword used to create an object ClassName() → Constructor 🔹 Example class Demo5 { int x = 100; int y = 200; } class MainClass3 { public static void main(String[] args) { Demo5 d1 = new Demo5(); System.out.println("x = " + d1.x); System.out.println("y = " + d1.y); System.out.println("modifying x & y"); d1.x = 300; d1.y = 400; System.out.println("x = " + d1.x); System.out.println("y = " + d1.y); } } Output: x = 100 y = 200 modifying x & y x = 300 y = 400 🔹 Important Observation When we write: Demo5 d1 = new Demo5(); Java performs three things: 1️⃣ Creates a reference variable (d1) 2️⃣ Creates a new object in memory 3️⃣ Stores the object reference in the variable #Java #CoreJava #JavaFullStack #OOP #Programming #BackendDevelopment #LearningInPublic #SoftwareDevelopment

The Magic of @SneakyThrows in Java: How Does It Break the Rules? Lombok’s @SneakyThrows often raises questions in code reviews. It allows us to throw a checked exception (like IOException) without adding a throws clause - something Java normally forbids. The Problem: Java forces you to catch checked exceptions or declare them. This is especially frustrating with lambdas, where adding a throws declaration isn't an option. How does this work? Lombok uses bytecode manipulation. It replaces your checked exception with a generic throw that bypasses the compiler's checks. At runtime, the exception is thrown normally, but the compiler never sees the violation. It’s a clean solution for edge cases - just use it intentionally. While @SneakyThrows makes the code look cleaner, it breaks the method signature contract. Consumers of your method won't know they need to handle that exception, which can lead to unexpected application crashes. It also violates the Principle of Least Astonishment - other developers reading the code won't expect a checked exception to appear out of nowhere, making debugging and maintenance more difficult. But despite these risks, it's hard to deny how pleasant @SneakyThrows feels to use. The code becomes so clean and readable - no more wrapping everything in try-catch blocks just to satisfy the compiler. When you're working with streams or quick scripts, that single annotation removes the noise and lets the business logic shine. Do you use @SneakyThrows in your projects? Let’s discuss below! 👇

Most Java mistakes I see in code reviews come from the same 20 misunderstandings. After reviewing thousands of pull requests, these patterns keep showing up, especially from developers in their first 2 years. Here is what trips people up the most: → Using == instead of .equals() for String comparison → Mutating Date objects when LocalDate exists → Throwing checked exceptions for programming errors → Using raw types instead of generics → Concatenating Strings in loops instead of StringBuilder → Writing nested null checks instead of using Optional → Defaulting to arrays when ArrayList gives you flexibility → Wrapping everything in synchronized when ConcurrentHashMap exists → Catching Exception instead of the specific type you expect → Making utility methods static when they should be instance methods → Using new String("hello") instead of string literals → Using Integer when int would suffice → Repeating type args instead of using the diamond operator → Manual close() in finally instead of try-with-resources → Using static final int constants instead of enums → Writing verbose for-if-add loops instead of streams → Using Arrays.asList when List.of gives true immutability → Spelling out full types when var keeps code clean → Writing boilerplate classes when records do the job → Concatenating strings with \n instead of using text blocks None of these are hard to fix once you see the pattern. The real problem is that nobody points them out early enough. Save this for your next code review. #Java #SoftwareDevelopment #Programming #CleanCode #CodingTips

Think var in Java is just about saving keystrokes? Think again. When Java introduced var, it wasn’t just syntactic sugar — it was a shift toward cleaner, more readable code.  So what is var? var allows the compiler to automatically infer the type of a local variable based on the assigned value. Instead of writing: String message = "Hello, Java!"; You can write: var message = "Hello, Java!"; The type is still strongly typed — it’s just inferred by the compiler.  Why developers love var:  Cleaner Code – Reduces redundancy and boilerplate  Better Readability – Focus on what the variable represents, not its type  Modern Java Practice – Aligns with newer coding standards  But here’s the catch: Cannot be used without initialization Only for local variables (not fields, method params, etc.) Overuse can reduce readability if the type isn’t obvious Not “dynamic typing” — Java is still statically typed  Pro Insight: Use var when the type is obvious from the right-hand side — avoid it when it makes the code ambiguous.  Final Thought: Great developers don’t just write code — they write code that communicates clearly. var is a tool — use it wisely, and your code becomes not just shorter, but smarter. Special thanks to Syed Zabi Ulla and PW Institute of Innovation for continuous guidance and learning support. #Java #Programming

Again, a good article from Sergiy Yevtushenko. Every developer should read this - it's Java, but the lessons are useful in many modern languages. Practical, applied programming tips like many devs appreciate them. These are not just "FP style examples in Java". They are also applied ways of properly decoupling concepts and mechanisms that should remain decoupled, but which traditional OOP languages tend to force us to couple. For example: handling errors with try-catch VS handling errors with Result<>, flatMap() etc. And don't forget to follow Sergiy Yevtushenko, his programming advice is always best of class. #Java #FunctionalProgramming #Programming #Architecture

The Diamond Problem in Java occurs in languages that allow multiple inheritance, where a class inherits from two classes that share a common superclass. This situation leads to ambiguity when both parent classes define the same method, raising the question of which method should be used. Java circumvents this issue by not supporting multiple inheritance with classes. However, a similar problem can arise with interfaces and default methods. Consider the following example: interface A { default void show() { System.out.println("A"); } } interface B { default void show() { System.out.println("B"); } } class Test implements A, B { public static void main(String[] args) { Test t = new Test(); t.show(); // This results in a compilation error } } In this case, since both interfaces provide the same method, Java requires the class to override it explicitly. Here’s how to resolve it with specific interface calls: class Test implements A, B { public void show() { A.super.show(); // Calls method from interface A B.super.show(); // Calls method from interface B } } This approach allows for explicit selection or combination of behavior from both interfaces. #Java #OOP #InterviewQuestions #BackendDevelopment #Programming

🚀 Day 5/100 — Loops in Java 🔁 Loops allow a program to repeat a block of code multiple times without writing the same code again and again. They are one of the most important concepts in programming. Java mainly provides three types of loops: 🔹 1. for Loop Used when the number of iterations is known. Syntax: for(initialization; condition; update){ // code to run } Example: for(int i = 1; i <= 5; i++){ System.out.println(i); } Output: 1 2 3 4 5 Here: i = 1 → start value i <= 5 → condition check i++ → increment after each iteration 🔹 2. while Loop Used when the number of iterations is unknown and depends on a condition. Example: int i = 1; while(i <= 5){ System.out.println(i); i++; } The loop runs as long as the condition is true. 🔹 3. do-while Loop Runs the block at least once, even if the condition is false. Example: int i = 1; do{ System.out.println(i); i++; }while(i <= 5); Difference: while → condition checked before execution do-while → condition checked after execution 🔹 Nested Loops A loop inside another loop is called a nested loop. Commonly used for pattern printing problems. Example: Triangle pattern for(int i = 1; i <= 5; i++){ for(int j = 1; j <= i; j++){ System.out.print("* "); } System.out.println(); } Output: * * * * * * * * * * * * * * * 🔴 Live Example — Inverted Triangle Pattern int rows = 5; for(int i = rows; i >= 1; i--){ for(int j = 1; j <= i; j++){ System.out.print("* "); } System.out.println(); } Output: * * * * * * * * * * * * * * * 🎯 Challenge: Write a program to print an inverted triangle pattern using nested loops. Drop your code in the comments 👇 #Java #CoreJava #100DaysOfCode #JavaLoops #ProgrammingJourney

🚀 Day 32 – Core Java | Static Concepts & Introduction to Inheritance Today’s session connected two important concepts in Java: Static members and the second pillar of OOP – Inheritance. 🔑 Key Concepts Learned ✔ Static Variable Belongs to the class, not the object Only one copy exists in memory Used when a value is common for all objects Example: Bank interest rate or mathematical constant π ➡ Advantage: Efficient memory utilization ✔ Static Block Static blocks execute during class loading, even before the main() method. Two major uses: • Initialize static variables • Execute code before the program enters main() Execution order: Static Variables → Static Block → main() Method Multiple static blocks are allowed, and they execute in the order written in the program. ✔ Static Method Static methods can be accessed without creating an object. Example scenario: Converting Miles → Kilometers does not depend on any object. So the method can be declared as static. Called using: ClassName.methodName() Example: Car.milesToKilometer(380); ➡ Advantage: No object creation → Better memory usage ✔ Static vs Instance Access Rule Important concept from Java execution: • Static members can access only static data directly • Instance members can access both static and instance data Reason: Instance variables get memory only when an object is created, but static members execute during class loading. So static code cannot access something that doesn't yet exist in memory. 🧩 Introduction to Inheritance (2nd Pillar of OOP) Inheritance allows one class to acquire properties and behaviors of another class. Definition: Inheritance is the process where one class acquires the properties and behaviors of another class. Example: class Hacker extends BankAccount Here: • BankAccount → Parent / Superclass • Hacker → Child / Subclass ✔ Advantages of Inheritance • Code Reusability • Reduced development time • Less effort in building similar applications Real-world example: Many games reuse mechanics from earlier games, modifying only certain features instead of rebuilding everything. ✔ Important Rule Private members do NOT participate in inheritance Reason: Private data is protected by Encapsulation, and inheritance cannot violate that protection. ✔ First Type of Inheritance Single Inheritance Parent Class → Child Class Example: BankAccount → Hacker 💡 Biggest Takeaway Understanding static execution, memory behavior, and inheritance helps developers write code that is: Efficient Reusable Scalable These concepts form the foundation for advanced Java topics like polymorphism and abstraction. #Day32 #CoreJava #JavaOOP #StaticKeyword #Inheritance #JavaProgramming #DeveloperJourney #LearningJava