Top 10 Coding exercises for Java Programmers


Here are the advanced Java coding challenges for developers looking to enhance their programming skills. These challenges require a deep knowledge of Java, data structures, and algorithms.

1. Reverse a String without `reverse` Method:

Develop a Java program to reverse a given string without using the built-in `reverse` Method.

2. Prime Number Checker:

Create a program determining whether a number is prime. It should process an array of numbers and return an array containing only the prime numbers.

3. Singleton Class:

Implement the Singleton design pattern in Java by creating a class with a non-parameterized constructor. It should have a public variable and a static method to retrieve the single instance.

4. MD5 Hash Generator:

Build a Java class from scratch that calculates the MD5 hash of an alphanumeric string. MD5 is a cryptographic algorithm for generating 128-bit hashes.

5. Lambda Expressions:

Write three Java lambda expressions. These expressions include one to check if a number is odd, another to determine if a number is prime, and the last to check if a string is a palindrome.

6. Phone Number Word Decoder:

Develop a program that accepts phone numbers with letters and converts them into a standardized format with digits, including parentheses and dashes.

7. Consecutive Numbers Checker:

Create a method to determine if an array of numbers can be rearranged to form consecutive numbers without duplicates.

8. Hex Code Finder:

Implement a Java method to search for a hex-encoded string within another string. It should return the index of the occurrence of the hex code.

Also Read: Proficiencies Required to be a Full Stack Java Developer

9. Reverse Letters in a String:

Write a Java method that reverses only the letters in a given string while keeping the numbers in order. For example, “ez56d” should become “ed56z.”

10. Pig Latin Translator:

Develop a method that converts words in a string to Pig Latin. In Pig Latin, you move the initial consonant(s) to the end of the word and append “ay.”

Read More: 10 Advanced Java Code Challenges