Interview Yatra

Top 20 Java Interview Questions and Answers for Freshers (2025 Edition) Preparing for your first Java interview can feel overwhelming. To help you, we’ve compiled the top 20 most frequently asked Java interview questions with expanded answers. These cover core concepts and practical knowledge that every fresher should be confident about. Part 1: Core Java Basics 1. What is Java? Java is a high-level, object-oriented, platform-independent programming language developed by Sun Microsystems (now owned by Oracle). Its key philosophy is “write once, run anywhere,” meaning code compiled into bytecode can run on any system that has the Java Virtual Machine (JVM). Java is widely used for web applications, enterprise systems, Android development, and cloud solutions because of its scalability, security, and community support. 2. What are the main features of Java? Java provides several powerful features: Platform Independence: Programs run across operating systems without recompilation. ...

Java String Coding Questions – Part 2 Top 15 Java String Coding Interview Questions – Part 2 1. Reverse a String Using Recursion public class ReverseRecursively { public static String reverse(String str) { if (str.isEmpty()) return str; return reverse(str.substring(1)) + str.charAt(0); } public static void main(String[] args) { System.out.println(reverse("Interview")); } } 2. Find All Permutations of a String public class StringPermutations { public static void permute(String str, String ans) { if (str.length() == 0) { System.out.println(ans); return; } for (int i = 0; i < str.length(); i++) { char ch = str.charAt(i); String ros = str.substring(0, i) + str.substring(i + 1); permute(ros, ans + ch); } } public static void main(String[] args) { permute("abc", "...

Top 15 Java String Coding Interview Questions Top 15 Java String Coding Interview Questions (With Answers) 1. Reverse a String public class ReverseString { public static void main(String[] args) { String input = "InterviewYatra"; String reversed = ""; for (int i = input.length() - 1; i >= 0; i--) { reversed += input.charAt(i); } System.out.println("Reversed: " + reversed); } } 2. Check if a String is a Palindrome public class PalindromeCheck { public static boolean isPalindrome(String str) { int i = 0, j = str.length() - 1; while (i < j) { if (str.charAt(i++) != str.charAt(j--)) return false; } return true; } public static void main(String[] args) { System.out.println(isPalindrome("madam")); // true } } 3. Count Vowels and Consonants public ...

Top 15 Real SQL Queries Asked in Backend Developer Interviews If you're preparing for a backend developer interview, SQL is one skill you can’t afford to ignore. Whether it's a startup or a product-based company like Amazon, Swiggy, or Paytm, SQL queries are commonly asked to test your data handling and logic-building ability. Here's a list of 15 real-world SQL queries that interviewers ask again and again — with sample table references and expected outputs. 1. Find the second highest salary from the Employee table. SELECT MAX(salary) AS Second_Highest_Salary FROM employee WHERE salary < (SELECT MAX(salary) FROM employee); 2. Retrieve employee details who have the highest salary in each department. SELECT * FROM employee e WHERE salary = ( SELECT MAX(salary) FROM employee WHERE department_id = e.department_id ); 3. Write a query to fetch duplicate records from a table. SELECT name, COUNT(*) FROM employee GROUP BY name HAVING COUNT(*) > 1; 4. Get emp...

Top 15 Java Multithreading Interview Questions – With Real-Life Examples Multithreading is a powerful feature in Java that allows concurrent execution of two or more threads. It helps in maximizing CPU utilization and building high-performance applications. In backend interviews, especially for product-based companies, questions related to Java concurrency and multithreading are asked frequently. Here are 15 top multithreading questions with real-world examples and answers you must prepare for interviews in 2025. 1. What is the difference between a process and a thread? Process: A process is an independent program in execution with its own memory space and resources. Thread: A thread is a lightweight sub-process. Multiple threads of a process share the same memory and can communicate easily with each other. 2. How do you create a thread in Java? There are two common ways: // 1. Extending Thread class class MyThread extends Thread { public void run() { System.out...

Spring Security Explained in Simple Words – JWT, OAuth2, Role-Based Access Introduction: Why Spring Security Matters When you're building a real-world application in Java using Spring Boot, security is not optional . You want to make sure only the right users access the right features. That’s where Spring Security comes in. But let’s be honest – most tutorials are too complex. So, in this post, let’s simplify Spring Security — including JWT , OAuth2 , and Role-Based Access Control (RBAC) — in plain language. 1. What is Spring Security? Spring Security is a powerful and customizable framework for securing Java applications. It provides: Authentication: Who are you? Authorization: What are you allowed to do? It acts as a security filter in your application and works well with: Spring MVC Spring Boot REST APIs 2. How Authentication Works in Spring Security Let’s say a user tries to log in: The user submits a login request ( username , password ) Spring Se...