Package com.guinetik.examples

Class FibonacciSequence

java.lang.Object
com.guinetik.examples.FibonacciSequence
public class FibonacciSequence extends Object
A utility class for generating and working with Fibonacci sequences.

Demonstrates various approaches to calculating Fibonacci numbers including iterative, recursive, and memoized implementations. This class is designed to showcase code coverage and documentation in Terminal Javadocs.

Fibonacci Definition

The Fibonacci sequence is defined as:


 F(0) = 0
 F(1) = 1
 F(n) = F(n-1) + F(n-2) for n > 1

Usage Example


 FibonacciSequence fib = new FibonacciSequence();
 long number = fib.calculate(10);  // Returns 55
 List<Long> sequence = fib.generateSequence(5);
Since:
2025
Version:
1.0.0
Author:
guinetik

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    MAX_SAFE_INDEX
    The maximum index for iterative calculation to avoid overflow

  • Constructor Summary

    Constructors
    Constructor
    Description
    FibonacciSequence()
    Creates a new FibonacciSequence calculator with an empty cache.

  • Method Summary

    Modifier and Type
    Method
    Description
    long
    calculate(int n)
    Calculates the nth Fibonacci number using iterative approach.
    long
    calculateMemoized(int n)
    Calculates the nth Fibonacci number using recursive approach with memoization.
    void
    clearCache()
    Clears the memoization cache.
    long
    findFirstGreaterThan(long threshold)
    Finds the first Fibonacci number that is greater than or equal to the threshold.
    List<Long>
    generateSequence(int count)
    Generates a Fibonacci sequence up to the specified count.
    int
    getCacheSize()
    Gets the current size of the memoization cache.
    boolean
    isFibonacciNumber(long number)
    Checks if a number is in the Fibonacci sequence.
    static void
    main(String[] args)
    Main entry point demonstrating Fibonacci sequence calculations.
    long
    sumSequence(int n)
    Calculates the sum of the first n Fibonacci numbers.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • MAX_SAFE_INDEX

      public static final int MAX_SAFE_INDEX
      The maximum index for iterative calculation to avoid overflow
      See Also:

  • Constructor Details

    • FibonacciSequence

      public FibonacciSequence()
      Creates a new FibonacciSequence calculator with an empty cache.

  • Method Details

    • calculate

      public long calculate(int n)
      Calculates the nth Fibonacci number using iterative approach.

      This is the most efficient approach for most use cases, with O(n) time complexity and O(1) space complexity.

      Parameters:
      n - the index of the Fibonacci number to calculate (0-based)
      Returns:
      the nth Fibonacci number
      Throws:
      IllegalArgumentException - if n is negative or exceeds MAX_SAFE_INDEX

    • calculateMemoized

      public long calculateMemoized(int n)
      Calculates the nth Fibonacci number using recursive approach with memoization.

      This approach uses caching to avoid redundant calculations. The first call will be slower, but subsequent calls benefit from the cache.

      Parameters:
      n - the index of the Fibonacci number to calculate (0-based)
      Returns:
      the nth Fibonacci number
      Throws:
      IllegalArgumentException - if n is negative

    • generateSequence

      public List<Long> generateSequence(int count)
      Generates a Fibonacci sequence up to the specified count.
      Parameters:
      count - the number of Fibonacci numbers to generate
      Returns:
      a list containing the first 'count' Fibonacci numbers
      Throws:
      IllegalArgumentException - if count is negative

    • findFirstGreaterThan

      public long findFirstGreaterThan(long threshold)
      Finds the first Fibonacci number that is greater than or equal to the threshold.
      Parameters:
      threshold - the minimum value to find
      Returns:
      the first Fibonacci number >= threshold, or -1 if none found within safe range
      Throws:
      IllegalArgumentException - if threshold is negative

    • sumSequence

      public long sumSequence(int n)
      Calculates the sum of the first n Fibonacci numbers.
      Parameters:
      n - the count of Fibonacci numbers to sum
      Returns:
      the sum of the first n Fibonacci numbers
      Throws:
      IllegalArgumentException - if n is negative

    • clearCache

      public void clearCache()
      Clears the memoization cache.

      This resets the cache to only contain the base cases (0 and 1).

    • getCacheSize

      public int getCacheSize()
      Gets the current size of the memoization cache.
      Returns:
      the number of cached values

    • isFibonacciNumber

      public boolean isFibonacciNumber(long number)
      Checks if a number is in the Fibonacci sequence.
      Parameters:
      number - the number to check
      Returns:
      true if the number is a Fibonacci number, false otherwise

    • main

      public static void main(String[] args)
      Main entry point demonstrating Fibonacci sequence calculations.
      Parameters:
      args - command line arguments (first argument is optional index)