FizzBuzzFunctionalEdition

A FizzBuzz implementation using functional programming principles in Java, leveraging streams, predicates, and functional composition.

About FizzBuzz

FizzBuzz is a classic programming problem used in interviews to test basic programming skills. The rules are:

For numbers 1 through 100:

• If the number is divisible by 3, print "Fizz"
• If the number is divisible by 5, print "Buzz"
• If the number is divisible by both 3 and 5 (15), print "FizzBuzz"
• Otherwise, print the number

Programming Paradigm

This implementation demonstrates functional programming principles:

• Immutability: No mutable state or variables
• Pure Functions: Functions without side effects
• Higher-Order Functions: Functions that take or return other functions
• Function Composition: Building complex behavior from simple functions
• Declarative Style: Expressing what to do, not how to do it
• Stream Processing: Data flows through transformation pipelines

Key Functional Features

1. IntPredicate: Functional interfaces for divisibility testing
2. IntFunction: Mapping numbers to their FizzBuzz representation
3. Method References: Clean, readable function references (System.out::println)
4. Lambda Expressions: Concise function definitions
5. Stream API: Functional data processing pipeline
6. Function Composition: Combining predicates with .and() operations

Code Structure

// Pure functional predicates
private static final IntPredicate isDivisibleBy3 = n -> n % 3 == 0;
private static final IntPredicate isDivisibleBy5 = n -> n % 5 == 0;
private static final IntPredicate isDivisibleBy15 = isDivisibleBy3.and(isDivisibleBy5);

// Pure mapping function
private static final IntFunction<String> fizzBuzzMapper = n ->
    isDivisibleBy15.test(n) ? "FizzBuzz" :
    isDivisibleBy3.test(n) ? "Fizz" :
    isDivisibleBy5.test(n) ? "Buzz" :
    String.valueOf(n);

// Functional pipeline
IntStream.rangeClosed(1, limit)
    .mapToObj(fizzBuzzMapper)
    .forEach(System.out::println);

Running the Code

# Compile
javac FizzBuzz.java

# Run
java FizzBuzz

Functional Programming Benefits

• Composability: Functions can be easily combined and reused
• Testability: Pure functions are easy to test in isolation
• Readability: Declarative code expresses intent clearly
• Parallelization: Immutable functions work well with parallel streams
• Debugging: No hidden state makes reasoning about code easier

Comparison with Other Editions

This repository is part of a programming paradigm showcase:

1. FizzBuzzImperativeEdition - Simple, procedural approach with for loops and if statements
2. FizzBuzzFunctionalEdition (this repo) - Functional programming with streams and predicates
3. FizzBuzzObjectOrientedEdition - Over-engineered enterprise OOP solution with patterns
4. FizzBuzzDeclarativeEdition - Declarative approach using expressions and pattern matching

Each demonstrates different programming paradigms and approaches to solving the same problem.

Prerequisites

• Java 8 or higher (required for streams and lambda expressions)
• Understanding of functional programming concepts is helpful but not required