Question

/*

This program should check if the given integer number is prime.

Reminder, an integer number greater than 1 is prime if

it divisible only by itself and by 1.

In other words a prime number divided by any other natural number

(besides 1 and itself) will have a non-zero remainder.

Your task:

Write a method called checkPrime(n) that will take

an integer greater than 1 as an input, and return true

if that integer is prime; otherwise, it should return false.

Your main() would prompt the user to enter an integer

greater than 1 and then call checkPrime() on that number.

The main() would then print a statement whether the

number was prime or not.

For example, the program output can look like this:

Please enter an integer greater than 1: 2473 <--(user input)

2473 is a PRIME!

or like this:

Please enter an integer greater than 1: 6981

6981 is a NOT a prime!

*/

import java.util.Scanner;

public class CheckPrimes {

//Returns true if n is prime

public static boolean checkPrime(int n){

/*

The strategy is pretty simple:

In a loop, try dividing number n

by every integer i starting from 2

and finishing with n/2

If a remainder from that division

is 0, that means that n is divisible by i

and n is not a prime (return false then).

  

If none of the divisions give you remainder 0,

then n is prime and you should return true.

*/

return true;

}

public static void main(String[] args) {

//No need to change the main()

Scanner scan = new Scanner(System.in);

System.out.print("Please enter an integer greater than 1: ");

int num = scan.nextInt();

System.out.println();

if (checkPrime(num))

System.out.println(num + " is a PRIME!");

else

System.out.println(num + " is NOT a prime!");

  

}

}

Answer 1

Program:

import java.util.Scanner;

public class CheckPrimes {
    
    public static boolean checkPrime(int n) {
        for(int i = 2; i <= n/2; ++i)
        {
            // condition for to check for nonprime number
            if(n % i == 0)
            {
                return false;
            }
        }
        return true;
    }
    
    public static void main(String args[]) {
        Scanner scan = new Scanner(System.in);
        System.out.print("Please enter an integer greater than 1: ");
        int num = scan.nextInt(); // Taking input from user
        System.out.println();
        // Calling function and printing output
        if (checkPrime(num))
            System.out.println(num + " is a PRIME!");
        else
            System.out.println(num + " is NOT a prime!");
    }
}

Output: