Question

Write a java program to print all the prime numbers below a certain given number. A prime number is defined as a number that can only be divided by 1 and itself.

Requirements:

1. Accept the upper limit from the user as an integer.

2. You can assume the user input will be positive and smaller than INT MAX

3. Go from 1 to the number. If you happen to find a number that is prime, print it. The input and output should match the sample run.

Please try and restrict yourself to loops, selection statements, and calls to library methods

Sample Run:

Enter the upper limit: 25

The prime numbers are:

2, 3, 5, 7, 11, 13, 17, 19, 23

Answer 1

//Primes.java
import java.util.Scanner;
public class Primes {
    private static boolean isPrime(int n) {
        for (int i = 2; i < n; i++) {
            if (n % i == 0) {
                return false;
            }
        }
        return true;
    }

    public static void main(String args[]) {
        int n;
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a number: ");
        n = scanner.nextInt();

        System.out.println("The prime numbers are:");
        for(int i = 2;i<=n;i++){
            if(isPrime(i)){
                System.out.print(i+" ");
            }
        }
        System.out.println();
    }
}