Core Java Coding Interview Questions


Core Java Coding Interview Questions

1. String Coding

  1. Reverse a string without using built-in reverse().

  2. Check if a string is a palindrome.

  3. Count the number of vowels and consonants in a string.

  4. Count occurrences of each character in a string.

  5. Find the first non-repeated character in a string.

  6. Remove duplicate characters from a string.

  7. Reverse each word in a sentence.

  8. Check if two strings are anagrams.

  9. Extract only digits from a string.

  10. Find the maximum occurring character in a string.

2. Array Coding

  1. Find the largest and smallest element in an array.

  2. Reverse an array.

  3. Check if an array is sorted or not.

  4. Find duplicate elements in an array.

  5. Remove duplicates from an array.

  6. Find second largest element.

  7. Find missing number in array 1 to N.

  8. Move all zeros to the end of array.

  9. Find pair of numbers whose sum is a given value.

  10. Merge two sorted arrays.

3. Number Programs

  1. Check if a number is prime.

  2. Check if a number is Armstrong.

  3. Check if a number is palindrome.

  4. Find factorial of a number.

  5. Print Fibonacci series.

  6. Find GCD & LCM of two numbers.

  7. Count digits in a number.

  8. Reverse a number.

  9. Find sum of digits.

  10. Check perfect number.

4. Collections Coding

  1. Sort a list without using sort().

  2. Convert array to list and list to array.

  3. Find frequency of each element in list/map.

  4. Remove duplicates from ArrayList.

  5. Find intersection of two lists.

  6. Find union of two lists.

5. Map & Set Coding

  1. Find first non-repeating element using HashMap.

  2. Sort HashMap by key.

  3. Sort HashMap by value.

  4. Check if two HashMaps are equal.

6. Java 8 Coding

  1. Find even numbers from list using streams.

  2. Find max and min using streams.

  3. Convert list to map using streams.

  4. Get duplicate elements using streams.

  5. Count occurrences using streams.

7. Miscellaneous

  1. Swap two numbers without third variable.

  2. Find longest word in a sentence.

  3. Print pattern programs (triangle, pyramid).

  4. Check if a given sentence is pangram.

  5. Implement custom exception.

If you want complete solutions for all 50 coding questions, or want “Selenium + Java coding questions”, just tell me!

Comments

Post a Comment

Popular posts from this blog

10 automation test cases for https://www.saucedemo.com/ (Sauce Demo)

 Here are 10 automation test cases for https://www.saucedemo.com/ (Sauce Demo), each with detailed steps and expected results . These are designed to simulate realistic user scenarios and we would be implemented using tools like Selenium, Cypress, or Playwright later. 🔹 Test Case 1: Valid Login Objective : Verify successful login with valid credentials. Steps : Navigate to https://www.saucedemo.com/ Enter Username : standard_user Enter Password : secret_sauce Click the Login button Expected Result : User is redirected to the inventory page ( /inventory.html ) with a list of products displayed. 🔹 Test Case 2: Invalid Login Objective : Validate error handling with incorrect credentials. Steps : Navigate to the login page Enter Username : invalid_user Enter Password : wrong_password Click the Login button Expected Result : Error message displayed: "Epic sadface: Username and password do not match any user in this service...
Read more

Java Roadmap for SDET Superstars!

Image
Java Roadmap for SDET Superstars! Your ultimate journey to mastering Java for test automation! Step 1: Java Basics – The Foundation Learn the grammar of Java 📚✨ 🧮 Variables & Data Types (int, float, boolean) ➕ Operators (+, -, *, /, %) 🔁 Loops (for, while, do-while) 🧠 Conditions (if-else, switch) 📦 Arrays & Strings Step 2: OOP – Think Like a Developer Become a Java ninja with Object-Oriented Programming 🐱‍👤⚔️ 🧱 Classes & Objects 🏗️ Constructors 👪 Inheritance 🎭 Polymorphism 🧬 Abstraction & Interfaces 🔐 Encapsulation Step 3: Exception Handling – Be Ready for Chaos Handle the unexpected like a pro! 🧨⚠️ try , catch , finally throw and throws 🚨 Custom Exceptions Step 4: Collections – Organize Like a Boss Work with lists, maps & sets like a data wizard 📦🪄 🗃️ List, Set, Map 🌀 ArrayList, HashMap, HashSet 🔁 Iteration (for-each, iterator) 🧠 Sorting & Filtering Step 5: Java 8+ – Modern & Cool Features Lev...
Read more

Mastering XPath in Selenium 4 🚀 – Supported Functions & Axes Explained

 Absolutely! Here's a complete list of XPath functions and axes supported by Selenium 4 (which uses XPath 1.0), with descriptions and examples . 🟢 XPath Features Supported by Selenium 4 🧭 ALL XPath Axes (13 Total) Axis Name Description ancestor:: All ancestors (parent, grandparent, etc.) of the current node ancestor-or-self:: All ancestors + the current node attribute:: All attributes of the current node (usually @attribute shorthand is used) child:: All direct children of the current node descendant:: All descendants (children, grandchildren, etc.) of the current node descendant-or-self:: All descendants + the current node following:: All nodes after the current node in the document following-sibling:: All sibling nodes after the current one namespace:: All namespace nodes of the current node (rarely used in HTML) parent:: Immediate parent of the current node preceding:: All nodes that come before the current node prece...
Read more