Hackerss.com

hackerss
hackerss

Posted on

Check if a numer is prime in Java

Check if a numer is prime - Java:


/**
* This class is used to check if a number is prime.
* @author 
* @version 1.0
*/
public class PrimeNumber {
   /**
   * This method checks if a number is prime.
   * @param number the number to check.
   * @return boolean true if the number is prime, false otherwise.
   */   
   public boolean isPrime(int number) {
       //Variable to store the result
       boolean result = true;
       //Check if the number is less than 2
       if (number < 2) {
           //It is not prime
           result = false;
       } else {
           //Check if the number is divisible by 2 or 3
           if (number % 2 == 0 || number % 3 == 0) {
               //It is not prime
               result = false;
           } else {
               //Check if the number is divisible by any other number from 5 to sqrt(number)
               for (int i = 5; i * i <= number; i += 6) {
                   if (number % i == 0 || number % (i + 2) == 0) {
                       //It is not prime
                       result = false;
                       break;
                   }
               }
           }
       }
       //Return the result
       return result;
   }

   /**
   * One Example
   */
   public static void main(String args[]) throws IOException {

      PrimeNumber  primeNumber= new PrimeNumber ();

      //Example 1: It is a prime number.
      int number = 7;

      //Output 1: It is a prime number.
      System.out.println("The number " + number + " is " + (primeNumber.isPrime(number) ? "" : "not ") + "a prime number.");

      //Example 2: It is not a prime number.
      number = 8;

      //Output 2: It is not a prime number.
      System.out.println("The number " + number + " is " + (primeNumber.isPrime(number) ? "" : "not ") + "a prime number.");

   }
}
Enter fullscreen mode Exit fullscreen mode

Top comments (0)