Definition of prime numbers:
For a number greater than 1, if it can no longer be divisible by other positive integers except 1 and itself, then we say it is a prime numbers.
Method to determine whether a number is a prime number (prime number):
If it is an even number, return directly; then start from 3, with a step size of 2, until the arithmetic square root of n, divide everything If not, it is a prime number.
Recommended: java video tutorial
Java method to determine whether a number is prime:
public class Main { public static void main(String[] args) { for (int j = 0; j <= 19; j++) { System.out.println(j+": "+isPrime(j) ); } } private static boolean isPrime(int src) { double sqrt = Math.sqrt(src); if (src < 2) { return false; } if (src == 2 || src == 3) { return true; } if (src % 2 == 0) {// 先判断是否为偶数,若偶数就直接结束程序 return false; } for (int i = 3; i <= sqrt; i+=2) { if (src % i == 0) { return false; } } return true; } }
For more java knowledge, please pay attention to java basics Tutorial column.
The above is the detailed content of Introduction to the method of determining whether a prime number is in Java. For more information, please follow other related articles on the PHP Chinese website!