Interview Yatra

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...