Java Coding Problems

updated July 28, 2024

These are the most common coding problems being asked during technical interviews, as I experienced it myself.

Running The Code

It's the convenience of Codespaces online! Simply create a Codespace, you don't need to install anything, just run using Bash.

Steps to Run the Code

1. Fork the Repository:

   • Navigate to the repository you want to fork.
   • Click the "Fork" button at the top right corner of the page.

2. Create a Codespace:

   • Go to your forked repository.
   • Click the "Code" button.
   • Select "Open with Codespaces" from the dropdown menu.
   • If you have Codespaces enabled, you will see an interface like this:

3. Navigate to the Source Directory:

   • Open the terminal in Codespaces.
   • Change the directory to src:

     cd src

4. Run the Java File:

   • Starting with Java 11, you can run Java files without compiling them first. Use the following command:

     java [NameOfTheFile].java

this is the sample interface of the online Codespaces

enjoy!

Source Code

1. Binary Search

   • Problem: Implement a binary search algorithm to find the position of a target value within a sorted array.
   • Link: View Code
   • Discussion: Binary search is an efficient algorithm for finding an item from a sorted list of items. It works by repeatedly dividing in half the portion of the list that could contain the item, until you've narrowed down the possible locations to just one.

2. Checking Palindrome

   • Problem: Check if a given string is a palindrome.
   • Link: View Code
   • Discussion: A palindrome is a word, phrase, number, or other sequence of characters that reads the same forward and backward (ignoring spaces, punctuation, and capitalization). The algorithm typically involves comparing characters from the beginning and end of the string moving towards the center.

3. Inheritance

   • Problem: Demonstrate the concept of inheritance in Java.
   • Link: View Code
   • Discussion: Inheritance is a fundamental concept in object-oriented programming where a new class is created from an existing class. The new class (subclass) inherits attributes and methods from the existing class (superclass), allowing for code reuse and the creation of a hierarchical relationship between classes.

4. Integer Array Sum

   • Problem: Calculate the sum of all integers in an array.
   • Link: View Code
   • Discussion: This problem involves iterating through an array of integers and accumulating the sum of its elements. It is a straightforward problem that demonstrates basic array manipulation and iteration.

5. Merge Sort

   • Problem: Implement the merge sort algorithm.
   • Link: View Code
   • Discussion: Merge sort is a divide-and-conquer algorithm that divides the input array into two halves, recursively sorts them, and then merges the sorted halves. It is known for its efficiency and stable sorting properties.

6. Prime Number Checker

   • Problem: Check if a given number is a prime number.
   • Link: View Code
   • Discussion: A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. The algorithm typically involves checking divisibility from 2 up to the square root of the number.

7. Fibonacci Series

   • Problem: Print the Fibonacci series up to a given number.
   • Link: View Code
   • Discussion: The Fibonacci series is a sequence where each number is the sum of the two preceding ones, usually starting with 0 and 1. This problem can be solved using iterative or recursive approaches.

8. Remove A Character

   • Problem: Remove all occurrences of a given character from a string.
   • Link: View Code
   • Discussion: This problem involves iterating through the string and building a new string that excludes the specified character. It demonstrates string manipulation techniques.

9. Remove Whitespaces

   • Problem: Remove all whitespaces from a string.
   • Link: View Code
   • Discussion: This problem involves iterating through the string and building a new string that excludes all whitespace characters. It is a common string manipulation task.

10. Reverse A Linked List

    • Problem: Reverse a singly linked list.
    • Link: View Code
    • Discussion: Reversing a linked list involves changing the direction of the pointers in the list. This problem is a classic example of pointer manipulation in data structures.

11. Reverse A String

    • Problem: Reverse a given string.
    • Link: View Code
    • Discussion: Reversing a string involves swapping characters from the beginning and end of the string moving towards the center. It is a basic string manipulation problem.

12. Shuffle Array

    • Problem: Shuffle the elements of an array randomly.
    • Link: View Code
    • Discussion: Shuffling an array involves randomly permuting its elements. This can be achieved using algorithms like the Fisher-Yates shuffle.

13. Sort Array

    • Problem: Sort an array of integers.
    • Link: View Code
    • Discussion: Sorting an array involves arranging its elements in a specific order (ascending or descending). Various algorithms can be used, such as quicksort, mergesort, or bubble sort.

14. Check Vowels

    • Problem: Check if a string contains any vowels.
    • Link: View Code
    • Discussion: This problem involves iterating through the string and checking for the presence of vowel characters (a, e, i, o, u). It demonstrates basic string traversal and condition checking.

License

This is based on :

https://www.journaldev.com/370/java-programming-interview-questions

I don't know about the specific license the author used but I'm still including his link for his copyright.

When you copy my work, include the author's link and my MIT license for my modifications.

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