Java examples for java.lang:int prime
Get the prime number above n
//package com.java2s; public class Main { /**//from w w w . j a va 2s . com * Get the prime number above n * @param n number * @return The next prime number after n. * If n is equal to 2147483647. Returns -1, as there are no integers greater than it. */ public static int getNextPrime(int n) { if (n == 2147483647) return -1; return (int) getNextPrime((long) n); } /** * Get the prime number above n * @param n number * @return The next prime number after n. * If n is equal to 9223372036854775783L. Returns -1, as there are no long greater than it. */ public static long getNextPrime(long n) { if (n < 2) return 2; if (n == 9223372036854775783L) return -1; for (long i = n + 1;; i++) if (isPrime(i)) return i; } /** * A primality test * @param n number to test * @return true if prime * false if composite */ public static boolean isPrime(int n) { return isPrime((long) n); } /** * A primality test * @param n number to test * @return true if prime * false if composite */ public static boolean isPrime(long n) { if (n == 2 || n == 3) return true; if (n % 2 == 0 || n % 3 == 0 || n < 2) return false; long sqrt = (long) Math.sqrt(n) + 1; for (long i = 6; i <= sqrt; i += 6) { if (n % (i - 1) == 0) return false; else if (n % (i + 1) == 0) return false; } return true; } }