Java Daemon Thread: Background Support for User Threads

# String Output Formatting Across Programming Languages In software development, consistent and readable output formatting is essential, especially for logs, reports, IDs, and timestamps. Example:- Formatting `7` as `007` using `%03d`.  ### Examples **C / C++** ``` printf("%03d", 7);  // Output: 007 ```` **Python** ``` print(f"{7:03d}") # Output: 007 ``` **Java** ``` System.out.printf("%03d", 7); String value = String.format("%03d", 7); ```` printf-style formatting, originally developed in C for output to stdout, was later adopted by C++, Java, and Python, with each language differing only in the method or function used to invoke it. This explains the similarity in naming and usage across these languages. Lina Alsawadi #SoftwareEngineering #Programming #Java #Python #C++

this() vs super() in Java: ✅ this() : this() is used to call another constructor of the same class. It helps in constructor chaining and avoids code duplication. Example: class Student { Student() { this(101); System.out.println("Default constructor"); } Student(int id) { System.out.println("Parameterized constructor: " + id); } public static void main(String[] args) { new Student(); } } Output: Parameterized constructor: 101 Default constructor 📌 this() must be the first statement in the constructor. ✅ super(): Definition: super() is used to invoke the immediate parent class constructor. It ensures the parent class object is created before the child class object. Example: class Parent { Parent() { System.out.println("Parent constructor"); } } class Child extends Parent { Child() { super(); System.out.println("Child constructor"); } public static void main(String[] args) { new Child(); } } Output: Parent constructor Child constructor #Java #OOP #this() #super() #TapAcademyBengaluru #Coding #TapAcademy

💡 Introduction to Collections in Java After completing core concepts like OOPs, Exception Handling, and Multithreading, I’m now starting a new and very important topic — Collections in Java 🚀 🔍 What is the Collection Framework? The Java Collection Framework is a group of classes and interfaces that provides a standard way to store, manage, and manipulate a group of objects. Instead of handling objects manually, collections give us ready-made data structures with powerful methods. 🧩 Main Components of Collections Some commonly used parts of the Collection Framework are: List → ArrayList, LinkedList Set → HashSet, TreeSet Map → HashMap, TreeMap Each collection has its own behavior and use case. ✅ Advantages of Collections ✔ Dynamic size (unlike arrays) ✔ Ready-made methods (add, remove, search, sort, etc.) ✔ Improves code reusability ✔ Reduces programming effort ✔ Better performance and flexibility ⚠️ Disadvantages of Collections ❌ Slightly slower than arrays (due to extra features) ❌ More memory usage ❌ Need to understand which collection to use in which scenario 🌍 Real-world example Think of a contact list in your phone 📱 You can add contacts, delete them, search, sort — all dynamically. That’s exactly how collections work in Java — managing data efficiently. 📘 Next Up: In the next posts, I’ll explore List interface, starting with ArrayList, its methods, and real-time use cases — step by step. #Java #CollectionsFramework #CoreJava #JavaDeveloper #TapAcademy

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

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

📘 Types of Inheritance in Java: 1️⃣ Single-Level Inheritance Single-level inheritance is a type of inheritance in which one child class directly inherits from one parent class, forming a simple IS-A relationship between two classes. 2️⃣ Multi-Level Inheritance Multi-level inheritance is a type of inheritance where a class is derived from another derived class, creating a chain of inheritance across multiple levels. 3️⃣ Hierarchical Inheritance Hierarchical inheritance occurs when multiple child classes inherit from a single parent class, allowing common functionality to be shared among different subclasses. 4️⃣ Multiple Inheritance Multiple inheritance is a type of inheritance in which a single child class inherits from more than one parent class. ❌ Java does not support multiple inheritance using classes to avoid ambiguity, but ✔ it is supported using interfaces. 5️⃣ Hybrid Inheritance Hybrid inheritance is a combination of two or more types of inheritance. ✔ In Java, hybrid inheritance is partially supported—it is allowed as long as it does not involve multiple inheritance using classes. ✔ Full hybrid inheritance is achieved using interfaces. 6️⃣ Cyclic Inheritance Cyclic inheritance occurs when a class directly or indirectly inherits from itself, forming a circular dependency. ❌ Java does not allow cyclic inheritance because it leads to infinite inheritance loops and compile-time errors. TAP Academy #Java #Inheritance #OopsConcepts #CoreJava #JavaInterview #ProgrammingFundamentals #TapAcademy

Mastering Wrapper Classes in Java: Converting Primitives to Objects If you are working with Java, you’ve likely used both int and Integer. But do you know why Java provides both? In Java, Wrapper Classes provide a way to use primitive data types (int, boolean, etc.) as objects. This is essential when working with Collections (like ArrayList or HashMap), which can only store objects, not primitives. The 8 Wrapper Classes Each primitive type has a corresponding wrapper class: Integer for int Double for double Character for char Boolean for boolean Float for float Long for long Byte for byte Short for short Key Concepts to Remember: 1. Autoboxing: The automatic conversion that the Java compiler makes between the primitive types and their corresponding object wrapper classes (e.g., converting int to Integer). 2. Unboxing: The reverse process—converting an object of a wrapper class back to its corresponding primitive type (e.g., Integer to int). Why do we need them? Collections Framework: List, Set, and Map require objects. Utility Methods: Wrapper classes provide useful methods for conversion (like Integer.parseInt()). Null Values: Objects can be null, whereas primitives always have a default value. Understanding these fundamentals is a huge step toward becoming a proficient Java developer! #Java #JavaProgramming #FullStackDeveloper #BackendDevelopment #CodingTips #SoftwareEngineering #LearningJava #JavaDeveloper #TechEducation #WrapperClasses

Recently, I spent some time revisiting Java Generics, and it explained me why they are such an important part of writing clean and reliable Java code. Generics allow us to define classes and methods that work with different data types while still providing compile-time type safety. This helps avoid unexpected runtime errors and makes the code easier to understand and maintain. A common problem without generics is relying on Object and manual type casting, which can easily lead to ClassCastException at runtime. Generics solve this by letting the compiler enforce the correct type usage. For example, imagine a box that is meant to store just one kind of thing at a time. class GiftBox<T> { private T gift; public void put(T gift) { this.gift = gift; } public T open() { return gift; } } public class GenericsExample { public static void main(String[] args) { GiftBox<String> messageBox = new GiftBox<>(); messageBox.put("Happy Birthday"); GiftBox<Integer> chocolateBox = new GiftBox<>(); chocolateBox.put(10); System.out.println(messageBox.open()); System.out.println(chocolateBox.open()); } } Here, the compiler ensures that a String box only contains strings and an Integer box only contains integers. #Java #JavaGenerics #Programming

Some limitations in programming languages are not weaknesses. They are deliberate design choices. In my latest blog, I explain the Java Diamond Problem and why Java chose safety and clarity over power. Read here: https://lnkd.in/g6HS9TwR #Java #SoftwareEngineering #DesignPrinciples #Programming

💡 Daemon Thread in Java In Java, a Daemon Thread is a background or helper thread that supports the execution of user threads. Its main purpose is to perform tasks that run in the background, and it automatically stops when all user threads finish execution. 🔍 Key Points ✔ Runs in the background ✔ Supports main/user threads ✔ JVM exits when only daemon threads are left ✔ Used for service-based tasks 📌 Common example: Garbage Collector 🌍 Real-world example Think of a watchman in a college campus 🏫 The watchman works only while students are present. Once all students leave, the watchman’s duty ends. 👉 Students → User threads 👉 Watchman → Daemon thread 💻 Simple Code Example class Helper extends Thread { public void run() { while (true) { System.out.println("Daemon thread running..."); try { Thread.sleep(500); } catch (InterruptedException e) { e.printStackTrace(); } } } } public class Demo { public static void main(String[] args) { Helper t = new Helper(); t.setDaemon(true); // Setting daemon thread t.start(); System.out.println("Main thread finished"); } } 📌 When the main thread ends, the daemon thread also stops automatically. ⚠️ Important Rules setDaemon(true) must be called before start() Daemon threads should not be used for important user tasks