Class SieveOfEratosthenes

java.lang.Object
org.troy.capstone.data_structures.item_table.SieveOfEratosthenes
public class SieveOfEratosthenes extends Object
Code originally sourced from the MindTap assignment, but modified to be more memory efficient by using a BitSet to track which numbers are not prime, and to include a method for getting the largest prime under 100 million. This Class implements the Sieve of Eratosthenes algorithm to find prime numbers up to a set max value.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private BitSet
    notAPrime
    A BitSet where the value at index i indicates whether i is not a prime number (true means not prime, false means potentially prime).

  • Constructor Summary

    Constructors
    Constructor
    Description
    SieveOfEratosthenes(int maxValue)
    Constructor for the SieveOfEratosthenes class, which initializes the sieve up to the specified maximum value.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    isPrime(int value)
    Checks if a given value is a prime number.
    Optional<Integer>
    maxPrimeUnder100mil()
    Gets the largest prime number under 100 million using the Sieve of Eratosthenes algorithm.
    private void
    releaseMemory()
    Releases the internal array to be eligible for garbage collection.
    static Optional<Integer>
    staticPrimeUnder100mil()
    Gets the largest prime number under 100 million using the Sieve of Eratosthenes algorithm.

    Methods inherited from class Object

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

  • Field Details

    • notAPrime

      private BitSet notAPrime
      A BitSet where the value at index i indicates whether i is not a prime number (true means not prime, false means potentially prime).

  • Constructor Details

    • SieveOfEratosthenes

      public SieveOfEratosthenes(int maxValue)
      Constructor for the SieveOfEratosthenes class, which initializes the sieve up to the specified maximum value.
      Parameters:
      maxValue - The maximum value up to which to calculate prime numbers. Must be a positive integer greater than or equal to 2.

  • Method Details

    • isPrime

      public boolean isPrime(int value)
      Checks if a given value is a prime number.
      Parameters:
      value - The value to check for primality. Must be a non-negative integer.
      Returns:
      true if the value is prime, false otherwise.

    • releaseMemory

      private void releaseMemory()
      Releases the internal array to be eligible for garbage collection.
      Postconditions:
      isPrime() will throw NullPointerException.

    • staticPrimeUnder100mil

      public static Optional<Integer> staticPrimeUnder100mil()
      Gets the largest prime number under 100 million using the Sieve of Eratosthenes algorithm.
      Returns:
      prime An Optional containing the largest prime number under 100 million, or empty if there was an error during calculation.
      Postconditions:
      isPrime() will throw NullPointerException due to memory release, as the sieve is no longer needed after finding the largest prime under 100 million.

    • maxPrimeUnder100mil

      public Optional<Integer> maxPrimeUnder100mil()
      Gets the largest prime number under 100 million using the Sieve of Eratosthenes algorithm.
      Returns:
      prime An Optional containing the largest prime number under 100 million, or empty if there was an error during calculation.