What are Prime Numbers? 

Prime numbers are divisible only by the number 1 or itself. It is Whole numbers greater than 1.  


For example:  2, 3, 5, 7 and 11 are the first few prime numbers.



How to display prime numbers between 1 to 100?

In this tutorial, We will learn how to get the prime numbers of any number. Here is a simple and well-commented example get the prime numbers.


Example:


public class JavaApplication {

    public static void main(String[] args) {

        int i;
        int num = 0;
        int numCheck = 100; // number
        boolean isPrime = true;

        //Empty String
        String primeNumbersFound = "";

        //Start loop 1 to numCheck
        for (i = 1; i <= numCheck; i++) {
            isPrime = CheckPrime(i);
            if (isPrime) {
                primeNumbersFound = primeNumbersFound + i + " ";
            }
        }
        System.out.println("Prime numbers from 1 to " + numCheck + " are:");
        // Print prime numbers from 1 to numCheck
        System.out.println(primeNumbersFound);
    }

    public static boolean CheckPrime(int numberToCheck) {
        int remainder;
        for (int i = 2; i <= numberToCheck / 2; i++) {
            remainder = numberToCheck % i;
            //if remainder is 0 than number is not prime
            if (remainder == 0) {
                return false;
            }
        }
        return true;

    }

}

Output:

run:
Prime numbers from 1 to 100 are:
1 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97