Java Exception Handling and String Basics for Interviews

💥 Java Interview Question 👉 What are the different types of Thread Priorities in Java? 👉 And what is the default priority assigned by JVM? Many developers ignore this… but it’s a very common interview question 👇 . 🧠 Core Concept In Java, every thread has a priority that helps the JVM decide: 👉 Which thread should get more CPU time Thread priority is represented by numbers from 1 to 10 . 🔢 Types of Thread Priorities ✔ MIN_PRIORITY = 1 👉 Lowest priority thread ✔ NORM_PRIORITY = 5 👉 Default priority assigned by JVM ✔ MAX_PRIORITY = 10 👉 Highest priority thread ⚡ Important Rule 👉 By default, every new thread gets: 🔥 NORM_PRIORITY (5) Unless you manually change it ⚠️ Real-World Understanding 👉 Higher priority does NOT guarantee execution . Why? ✔ Thread scheduling depends on OS ✔ JVM uses priority as a hint, not a rule . 💻 Example Code 𝒄𝒍𝒂𝒔𝒔 𝑻𝒆𝒔𝒕 {   𝒑𝒖𝒃𝒍𝒊𝒄 𝒔𝒕𝒂𝒕𝒊𝒄 𝒗𝒐𝒊𝒅 𝒎𝒂𝒊𝒏(𝑺𝒕𝒓𝒊𝒏𝒈[] 𝒂𝒓𝒈𝒔) {     𝑻𝒉𝒓𝒆𝒂𝒅 𝒕1 = 𝒏𝒆𝒘 𝑻𝒉𝒓𝒆𝒂𝒅();      𝑺𝒚𝒔𝒕𝒆𝒎.𝒐𝒖𝒕.𝒑𝒓𝒊𝒏𝒕𝒍𝒏(𝒕1.𝒈𝒆𝒕𝑷𝒓𝒊𝒐𝒓𝒊𝒕𝒚()); // 𝑫𝒆𝒇𝒂𝒖𝒍𝒕 = 5        𝒕1.𝒔𝒆𝒕𝑷𝒓𝒊𝒐𝒓𝒊𝒕𝒚(𝑻𝒉𝒓𝒆𝒂𝒅.𝑴𝑨𝑿_𝑷𝑹𝑰𝑶𝑹𝑰𝑻𝒀);     𝑺𝒚𝒔𝒕𝒆𝒎.𝒐𝒖𝒕.𝒑𝒓𝒊𝒏𝒕𝒍𝒏(𝒕1.𝒈𝒆𝒕𝑷𝒓𝒊𝒐𝒓𝒊𝒕𝒚()); // 10   } } 🎯 Interview Gold Answer 👉 “In Java, thread priority ranges from 1 to 10. The default priority is NORM_PRIORITY (5). However, thread scheduling is OS-dependent, so higher priority does not guarantee execution.” . 🚀 Why This Matters ✔ Helps understand thread scheduling ✔ Important for performance tuning ✔ Frequently asked in interviews . 👉 What is the default thread priority in Java? A) 1 B) 5 C) 10 💬 Comment your answer 👇 . 👉 Want more Java interview content? Comment “JAVA” 👇 👉 Follow for daily tech content 🚀 . . #Java #Multithreading #JavaDeveloper #Programming #SoftwareEngineering #CodingInterview #TechInterview #LearnJava #Developers #JavaInterview #Threading #Concurrency #Upskill #TechCareers

🚀 Java Interview Questions – Test Your Fundamentals As part of my interview preparation, I’ve been revising core Java concepts. Sharing some real interview questions I came across 👇 --- 🔹 Q1: What are the 4 pillars of OOP? 🔹 Q2: What is the difference between Encapsulation and Abstraction? 🔹 Q3: Why does Java not support multiple inheritance using classes? 🔹 Q4: What is the difference between Method Overloading and Method Overriding? --- 🔹 Q5: Difference between List, Set, and Map? 🔹 Q6: Why is HashMap so fast? 🔹 Q7: What is hashCode() and equals()? Why are they important? 🔹 Q8: What is collision in HashMap and how is it handled? --- 🔹 Q9: Why is ArrayList fast for reading but slow for insertion? 🔹 Q10: Why is String immutable in Java? --- 🔹 Q11: Difference between Checked and Unchecked exceptions? 🔹 Q12: What is finally block? Will it always execute? --- 🔹 Q13: What is a race condition in multithreading? 🔹 Q14: Difference between start() and run()? --- 🔹 Q15: What is a Lambda expression? 🔹 Q16: Difference between map() and filter() in Streams? --- 💡 Trying to strengthen my fundamentals step by step and become interview-ready 💻 👉 How many can you answer correctly? #Java #JavaDeveloper #InterviewQuestions #LearningInPublic #SoftwareEngineering #TechCareers

🔥 Java Interview Trap – Null with Method Overloading 🔥 This one looks EASY… but breaks many developers in interviews 😏 👉 Question: public class Test { static void print(String str) { System.out.println("String"); } static void print(Object obj) { System.out.println("Object"); } public static void main(String[] args) { print(null); } } 👉 Output: String 💡 Why this happens? 👉 "null" can match any reference type But Java chooses the MOST SPECIFIC method - String is more specific than Object ✔️ - So "print(String)" is called 🚨 Now the REAL trap: 👉 Add this method: static void print(Integer i) { System.out.println("Integer"); } 👉 Now call: print(null); 💥 Result: Compilation Error ❌ 💡 Why error? 👉 Now Java is confused: - String OR Integer → both are equally specific 👉 So it becomes AMBIGUOUS 💥 Golden Rule: 👉 Java always picks MOST SPECIFIC method 👉 If confusion → COMPILE-TIME ERROR 🎯 Interview Tip: When you see "null" + overloading → think AMBIGUITY #Java #JavaInterview #CodingInterview #Developers #Programming #TechTips

I am on my journey to master Java’s most confusing interview concepts, and I thought of sharing a few learnings here 🚀 Today, I tackled one of the most commonly asked (and confusing) topics: Comparator vs Comparable 🔹 Comparable An interface that provides the compareTo() method where we define the default sorting logic • Defined inside the class • Supports only ONE sorting logic eg- class Student implements Comparable<Student> { int marks; public int compareTo(Student other) { return Integer·compare(this.marks, other.marks); } } 🔹 Comparator An interface that provides the compare() method for custom sorting • Defined outside the class • Supports MULTIPLE sorting logics eg- list.sort((a, b) -> Integer·compare(a.marks, b.marks)); // sort by marks list.sort((a, b) -> a.name.compareTo(b·name)); // sort by name 🔥 The real takeaway ✔ Comparable → One default behavior ✔ Comparator → Many dynamic behaviors ⚡ Interview trap (important) ❌ Don’t write: return a - b; 👉 Can cause integer overflow ✅ Always prefer: Integer·compare(a, b); 🧠 Mental note Ascending → (a, b) Descending → (b, a) If you're preparing for Java interviews, mastering this concept can save you from a LOT of confusion 🤯 #Java #DSA #InterviewPrep #BackendDevelopment #Programming #SoftwareEngineering

🔥 Java Interview Must-Know: == vs equals() vs hashCode() This is one of the most asked questions in interviews. 💡 Key Differences: ✔ == - Compares references - Works for primitives & objects ✔ equals() - Compares values - Defined in Object class - Can be overridden ✔ hashCode() - Used in hashing collections - Must be consistent with equals() 🔹 Important Rule: If two objects are equal → their hashCode must be same 🔹 Real Example: Map<String, String> map = new HashMap<>(); map.put(new String("key"), "value"); 👉 Without proper equals & hashCode → data retrieval may fail ⚠️ Common Mistake: Overriding equals() but not hashCode() Master this → You clear many Java interviews easily. #JavaInterview #HashMap #Java #CodingInterview #Developers

📌 **Java Interview Questions** ❓ *Question-7: Which collection allows duplicates?* A) Set (😂) B) Map (👍) C) List (❤️) D) EnumSet (🔥) ✅ *Answer:* C) List --- ❓ *Question-8: What does JVM stand for?* A) Java Variable Machine (👍) B) Java Virtual Method (😂) C) Java Virtual Machine (❤️) D) Java Verified Machine (🔥) ✅ *Answer:* C) Java Virtual Machine --- ❓ *Question-9: What is the size of `int` in Java?* A) 2 bytes (😂) B) 4 bytes (❤️) C) 8 bytes (🔥) D) Depends on system (👍) ✅ *Answer:* B) 4 bytes --- 💡 *Save this for your interviews!* #java #javainterview #coding #programming #javaquiz #developers #ashokit #interviewquestions Follow @ashokitschool for more updates 🚀

🚀 30 Days of Java Interview Questions – Day 23 💡 Question: What is ThreadLocal in Java and how does it work internally? This is a rare and tricky question often asked in backend and multithreading interviews. 🔹 What is ThreadLocal? ThreadLocal is a class that provides thread-specific variables. Each thread has its own independent copy of the variable. 🔹 Why Use ThreadLocal? Used when you want to avoid sharing data between threads. Example use cases: • Database connections • User sessions • Transactions 🔹 How It Works Internally Each Thread has its own ThreadLocalMap Thread → ThreadLocalMap → (ThreadLocal, Value) So every thread stores its own value separately 🔹 Example ```java class Test { static ThreadLocal<Integer> threadLocal = new ThreadLocal<>(); public static void main(String[] args) { threadLocal.set(100); System.out.println(threadLocal.get()); // 100 } } ``` 🔹 Important Methods set(value) → store value get() → retrieve value remove() → remove value (important to prevent memory leaks) 🔹 Important Points • Each thread has its own copy • No synchronization required • Must call remove() to avoid memory leaks ⚡ Quick Summary • ThreadLocal → thread-specific storage • Internally uses ThreadLocalMap • Helps in thread isolation 📌 Interview Tip Mention this line to stand out: “ThreadLocal avoids synchronization by giving each thread its own copy of data.” Follow this series for more advanced Java interview questions. #java #javadeveloper #multithreading #threadlocal #codinginterview #backenddeveloper #softwareengineer #programming

🚀 Java Backend Interview Series – Day 9 Multithreading is where interviews get serious 👇 ⚡ Multithreading (Advanced): 1️⃣ Difference between Thread and Runnable? 2️⃣ Runnable vs Callable – when to use which? 3️⃣ What is ExecutorService? Types of thread pools? 4️⃣ What is race condition vs visibility problem? 5️⃣ How does `volatile` solve visibility issues? 6️⃣ What happens when a thread calls `wait()`? 7️⃣ Difference between `wait()` and `sleep()`? 8️⃣ What is ThreadLocal and where is it used? 9️⃣ What is CountDownLatch vs CyclicBarrier? 🔟 How do you ensure execution order between threads? 💡 Multithreading questions = real backend capability check 📌 Save this for revision 👇 Comment “NEXT” for Day 10 #Java #Multithreading #Concurrency #BackendDevelopment #InterviewPrep #SoftwareEngineering #Developers #Coding

📌 Java Interview Questions 📌 Question 25: Which of the following is not a feature of Java? A) Platform Independent   B) Object-Oriented   C) Pointers   D) Robust  📌 Question 26: Which operator is used to compare two values? A) =   B) ==   C) :=  D) equals  📌 Question 27: Which method is used to start a thread? A) run()   B) begin()  C) execute()  D) start()  . #java #javainterview #coding #programming #javaquiz #developers #ashokit #interviewquestions

Java Collections Interview Prep with importance level – Real Q&A Style (5 LPA Ready) Today I revised some high-impact interview questions from Java Collections. Sharing quick, crisp answers that actually help in interviews 👇 Q1: Is Set index-based? No, Set is not index-based. It stores unique elements and does not support index access. Q2: Does HashSet use HashMap internally? Yes, HashSet internally uses HashMap. Q3: What does “underlying data structure is hash table” mean for HashSet? HashSet → uses HashMap → HashMap uses hash table So indirectly, HashSet is based on a hash table. Q4: Difference between HashMap and Hashtable? HashMap is not synchronized and faster. Hashtable is synchronized, thread-safe but slower, and does not allow null. Q5: Can HashMap, HashSet, Hashtable store null? HashMap → 1 null key + multiple null values HashSet → 1 null element Hashtable → ❌ no null key or value Q6: TreeSet & TreeMap sorting logic? Default → Comparable (compareTo) Custom → Comparator (compare) If comparison fails → ClassCastException Q7: Are Collections synchronized? Most are NOT synchronized Only legacy classes (Vector, Stack, Hashtable) are synchronized Key takeaway: “Focus on concepts like hashing, sorting, and differences — that’s what interviewers test.” Currently preparing for Java + Spring Boot interviews More such concise revisions coming soon! #Java #SpringBoot #DSA #InterviewPreparation #JavaCollections #CodingJourney