Afzal Khan’s Post

⚙️ Java Multithreading: Run Multiple Tasks at the Same Time Multithreading is what gives Java the power to handle multiple operations concurrently making your applications faster, more responsive, and efficient. Here’s what you’ll learn in this guide: 🧠 What Is Multithreading? → Learn how multiple threads share memory but execute independently for improved performance. 💡 Creating Threads (2 Ways) → Extend the Thread class or implement the Runnable interface — both lead to parallel execution. 🚀 Starting Threads → Always use start() to launch a new thread; calling run() directly won’t create concurrency. 🔄 Thread Lifecycle → Understand thread states — New, Runnable, Running, Waiting, and Terminated. ⚙️ Key Thread Methods → Control execution using sleep(), join(), isAlive(), and setPriority(). 🔐 Synchronization → Prevent race conditions by locking shared resources with the synchronized keyword. 📈 Benefits of Multithreading → Maximize CPU usage, handle I/O and computation together, and deliver high-performing apps. 🎯 Interview Prep → Master differences between Thread vs Runnable, and key methods like join() and synchronized. 📌 Like, Save & Follow CRIO.DO for more advanced Java lessons made simple. 💻 Learn Java by Doing, Not Just Watching At CRIO.DO, you’ll master multithreading, synchronization, and concurrency by building real backend systems from scratch. 🚀 Join your FREE trial today - https://lnkd.in/e5UETdzC and start coding projects that perform like pros! #Java #Multithreading #CrioDo #LearnCoding #SoftwareDevelopment #Concurrency #BackendEngineering #JavaThreads #OOP #JavaInterview

☕ 5 Interesting Core Java Concepts Most Developers Overlook 🚀 Even after years with Java, it still surprises us with small gems 💎 Here are a few underrated but powerful features 👇 1️⃣ String Interning String a = "Java"; String b = new String("Java"); System.out.println(a == b.intern()); // true ✅ 👉 Saves memory by storing one copy of each unique string literal. 2️⃣ Transient Keyword Prevents certain fields from being serialized. Perfect for sensitive info like passwords 🔒 class User implements Serializable { transient String password; } 3️⃣ Volatile Keyword Used in multithreading — ensures visibility across threads 🔁 volatile boolean flag = true; 4️⃣ Static Block Execution Order Static blocks run once — before the main method! static { System.out.println("Loaded before main!"); } 5️⃣ Shutdown Hook Run cleanup code before JVM exits gracefully 🧹 Runtime.getRuntime().addShutdownHook(new Thread(() -> System.out.println("Cleaning up before exit...") )); --- 💡 Pro Tip: > “Mastering Java isn’t about writing code faster — it’s about knowing what’s happening behind the scenes.” 🧠 👉 Question: Which one of these did you know already? Or got you saying “Wait… what? 😅” #Java #CoreJava #ProgrammingTips #CleanCode #SoftwareDevelopment #LearningInPublic #CodeBetter #JavaDeveloper #CodingJourney #TechTips #springboot #backend #developers #JavaProgramm

📌 Java Collections Cheat Sheet – Master Lists, Sets, Maps, Queues, and Stacks If you’re a Java developer, you already know: mastering Collections Framework is non-negotiable. But remembering all the methods across List, Set, Map, Queue, and Stack during coding or interviews can be overwhelming. That’s why I created this Java Collections Cheat Sheet — a quick reference with syntax, methods, and examples. 📌 What’s inside: ✅ How to construct collections: ArrayList, HashSet, TreeMap, LinkedList, Stack ✅ Universal methods (size(), clear(), equals(), toString()) ✅ List methods: get(), set(), subList(), indexOf() ✅ Stack methods: push(), pop(), peek() ✅ Queue methods: add(), remove(), peek() ✅ Map methods: put(), get(), containsKey(), values() ✅ Bonus: String & Random class handy methods ➕ Follow Harshitha Shapuram for more and useful updates #Java #Collections #CodingTips #InterviewPrep #SoftwareEngineering #DataStructures

👉 Reversing a Linked List in Java. Here’s a simple and clean iterative approach 👇 public class ReversedLinkList { public static void main(String[] args){ ListNode head = new ListNode(0);     head.next = new ListNode(1);     head.next.next = new ListNode(2);     head.next.next.next = new ListNode(5);     head.next.next.next.next = new ListNode(7);     ListNode ans = reverseList(head);     while(ans != null){       System.out.print(ans.val + " ");       ans = ans.next;     }   }   public static ListNode reverseList(ListNode head){     ListNode pre = null;     ListNode cur = head;     while(cur != null){       ListNode next = cur.next; // store next node       cur.next = pre;      // reverse the link       pre = cur;        // move 'pre' ahead       cur = next;        // move 'cur' ahead     }     return pre;   } } The logic is simple: Keep track of three pointers — pre, cur, and next. Reverse the direction of cur.next one node at a time. Move all pointers forward until you reach the end. 🔁 Output: 7 5 2 1 0 What’s your favorite linked list problem to explain in interviews? #Java #DSA #LinkedList #Coding #LearnByBuilding #Programming

🧵 Inter-Thread Communication in Java: How Threads Talk to Each Other. Here’s what you’ll master in this guide: ▪️ What Is Inter-Thread Communication? → A mechanism that lets threads work together instead of competing — essential for smooth concurrency. ▪️ wait() Method → Puts a thread to sleep and releases its lock until another thread signals it to resume. ▪️ notify() Method → Wakes one waiting thread on the same object, letting it continue execution. ▪️ notifyAll() Method → Wakes all threads waiting on the same object, which then compete to acquire the lock. ▪️ Synchronization Rule → All three methods must be used inside a synchronized block or method to avoid race conditions. ▪️ Producer-Consumer Example → Learn the classic synchronization pattern where one thread produces data and another consumes it efficiently. ▪️ Common Pitfalls → Forgetting synchronized, mishandling InterruptedException, or overusing notifyAll() can cause tricky bugs. ▪️ Interview Q&A → Understand real-world scenarios, timing issues (notify before wait), and why inter-thread communication underpins modern concurrent systems. Mastering inter-thread communication helps you write safe, high-performance, and scalable multithreaded Java applications. 📌 Like, Save & Follow CRIO.DO to learn Java from real-world use cases, not just theory. 💻 Build Hands-On Multithreaded Projects At CRIO.DO, you’ll implement producer-consumer systems, thread pools, and synchronization models by coding them yourself the way real engineers learn. 🚀 Start your FREE trial today - https://lnkd.in/gyFgTGUw and learn to build concurrency the right way! #Java #Multithreading #InterThreadCommunication #CrioDo #LearnCoding #Concurrency #ProducerConsumer #SoftwareDevelopment #JavaInterview #BackendEngineering

☕ Day 18 of my “Java from Scratch” series — “Command Line Arguments in Java” Ever wondered how we can pass inputs directly while running a Java program? 🤔 That’s where Command Line Arguments come in! 📘 What are Command Line Arguments? We can pass arguments to our program at runtime through the terminal. 🧩 Syntax: java ClassName argument1 argument2 ✅ Example: java HelloWorld Hi Java 🧾 Output: Hi Java 💡 Code: public class HelloWorld { public static void main(String[] args) { System.out.println(args[0]); System.out.println(args[1]); } } 🧠 Real-time Use Case: In real-world applications, we pass arguments like port numbers, log levels, and config paths to the JVM while running the application. ⚙️ How to pass arguments in Eclipse IDE: 1️⃣ Right-click on your main class 2️⃣ Go to Run As → Run Configurations 3️⃣ Select your class 4️⃣ Click Arguments on the right 5️⃣ Enter your program arguments 6️⃣ Click Run 🚀 📌 Note: Even if we pass numbers as arguments, Java treats them as Strings. #Java #Programming #JavaFromScratch #LearningSeries #Developers #Coding #CommandLineArgumentsInJava #Tech #SoftwareDeveloper #JavaLearning #InterviewConceptsInJava #NeverGiveUp

☕ Day 16 of my “Java from scratch” series “Dynamic Inputs in Java” 🎯 What is it? The values for variables can be decided at runtime. For this, we use the Scanner class. 🧩 Syntax: Scanner sc = new Scanner(System.in); int value1 = sc.nextInt(); String string = sc.nextLine(); String string2 = sc.next(); ⚠️ Note: There is a small issue in Java when taking inputs of different types (like int and String) one after another. If we take an int input first and then a String input immediately, the string input might be skipped 😅 👉 This happens because after entering the integer, we press Enter, and that newline character (\n) is still left in the input buffer. So when the next input (like nextLine()) is called, it reads that leftover newline instead of waiting for new input. ✅ Solution: To fix this, we add an extra sc.nextLine() to consume the leftover newline character before reading the next string. 🧠 Example: Scanner sc = new Scanner(System.in); System.out.print("Enter an integer: "); int value1 = sc.nextInt(); sc.nextLine(); // consume the leftover newline System.out.print("Enter a string: "); String string = sc.nextLine(); System.out.println("Integer: " + value1); System.out.println("String: " + string); 💡 Key takeaway: Always remember to handle newline characters properly when using Scanner for mixed inputs — it’s one of those small details that separates a beginner from a smart Java developer 😎 #Java #Programming #JavaBeginners #Coding #SoftwareDevelopment #JavaFromScratch #LearnJava #Tech #InterviewQuestions #NeverGiveUp

📌 Java Collections Cheat Sheet – Master Lists, Sets, Maps, Queues, and Stacks If you’re a Java developer, you already know: mastering Collections Framework is non-negotiable. But remembering all the methods across List, Set, Map, Queue, and Stack during coding or interviews can be overwhelming. That’s why I created this Java Collections Cheat Sheet — a quick reference with syntax, methods, and examples. 📌 What’s inside: ✅ How to construct collections: ArrayList, HashSet, TreeMap, LinkedList, Stack ✅ Universal methods (size(), clear(), equals(), toString()) ✅ List methods: get(), set(), subList(), indexOf() ✅ Stack methods: push(), pop(), peek() ✅ Queue methods: add(), remove(), peek() ✅ Map methods: put(), get(), containsKey(), values() ✅ Bonus: String & Random class handy methods ➕ Follow Supriya Darisa for more and useful updates #Java #Collections #CodingTips #InterviewPrep #SoftwareEngineering #DataStructures