Java Code:
import java.io.*;
public class PrimeCheck {
// Function to check if a number is prime
public static boolean isPrime(int num) {
// Corner cases: 0, 1 and negative numbers are not prime
if (num <= 1) {
return false;
}
// Check divisibility from 2 to square root of the number
for (int i = 2; i * i <= num; i++) {
if (num % i == 0) {
return false;
}
}
// If no divisor is found
// the number is prime
return true;
}
public static void main(String[] args) {
int num = 17;
if (isPrime(num)) {
System.out.println(num + " is a prime number.");
} else {
System.out.println(num + " is not a prime number.");
}
}
}
Output :
17 is a prime number.Explanation:
- The isPrime() method takes an integer num as input and returns true if the number is prime and false otherwise.
- We first handle corner cases: 0, 1 and negative numbers are not prime, so we return false for such cases.
- We iterate from 2 to the square root of the number (i * i <= num).If num is divisible by any number in this range (num % i == 0) then it is not prime and we return false.
- If no divisor is found in the range, the number is prime and we return true.
- In the main() method, we test the isPrime() function with a sample number (num = 17).
- Depending on the result. we print whether the number is prime or not.
