Class Primes

java.lang.Object
org.apache.commons.numbers.primes.Primes

public final class Primes extends Object
Methods related to prime numbers in the range of int.
  • primality test
  • prime number generation
  • factorization
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    (package private) static final String
    Exception message format when an argument is too small.
  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    Utility class.
  • Method Summary

    Modifier and Type
    Method
    Description
    static boolean
    isPrime(int n)
    Primality test: tells if the argument is a (provable) prime or not.
    static int
    nextPrime(int n)
    Return the smallest prime greater than or equal to n.
    static List<Integer>
    primeFactors(int n)
    Prime factors decomposition.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • NUMBER_TOO_SMALL

      static final String NUMBER_TOO_SMALL
      Exception message format when an argument is too small.
      See Also:
  • Constructor Details

    • Primes

      private Primes()
      Utility class.
  • Method Details

    • isPrime

      public static boolean isPrime(int n)
      Primality test: tells if the argument is a (provable) prime or not.

      It uses the Miller-Rabin probabilistic test in such a way that a result is guaranteed: it uses the firsts prime numbers as successive base (see Handbook of applied cryptography by Menezes, table 4.1).

      Parameters:
      n - Number to test.
      Returns:
      true if n is prime. All numbers < 2 return false.
    • nextPrime

      public static int nextPrime(int n)
      Return the smallest prime greater than or equal to n.
      Parameters:
      n - Positive number.
      Returns:
      the smallest prime greater than or equal to n.
      Throws:
      IllegalArgumentException - if n < 0.
    • primeFactors

      public static List<Integer> primeFactors(int n)
      Prime factors decomposition.
      Parameters:
      n - Number to factorize: must be ≥ 2.
      Returns:
      the list of prime factors of n.
      Throws:
      IllegalArgumentException - if n < 2.