A simple java program that takes a number, and prints that many primes.

PrimeByNumber.java

package com.rushilsrivastava.prime;

import java.util.Scanner;

public class PrimeByNumber {

    public static void main(String[] args) {

        System.out.println("How many prime numbers would you like to calculate? ");
        Scanner sc = new Scanner(System.in);
        int numbers = sc.nextInt();

        //loop through the numbers one by one
        int counter = 0;
        int i = 0;
        while (counter < numbers) {
            boolean isPrime = isPrime((long) i);
            // print the number
            if (isPrime) {
                System.out.print(i + " ");
                counter++;
            }
            i++;
        }
    }

    public static boolean isPrime(long n) {
        if (n < 2) return false;
        if (n == 2 || n == 3) return true;
        if (n % 2 == 0 || n % 3 == 0) return false;
        long sqrtN = (long) Math.sqrt(n) + 1;
        for (long i = 6L; i <= sqrtN; i += 6) {
            if (n % (i - 1) == 0 || n % (i + 1) == 0) return false;
        }
        return true;
    }
}