Java program to print prime numbers, a user input how many of them are required. Remember, the smallest prime number is 2. We use the sqrt method of Math package, which finds the square root of a number. To check if an integer (say n) is prime, you can check if it's divisible by any integer from 2 to (n-1) or check from 2 to sqrt(n), the first one is less efficient and takes more time.
Print prime numbers in Java
class PrimeNumbers
{
public static void main(String args[])
{
int n, status = 1, x = 3, count, j;
Scanner in = new Scanner(System.in);
System.out.println("Enter the number of prime numbers you want");
n = in.nextInt();
if (n >= 1)
{
System.out.println("First "+n+" prime numbers are:");
System.out.println(2);
}
for (count = 2; count <=n; )
{
for (j = 2; j <= Math.sqrt(x); j++)
{
if (x%j == 0)
{
status = 0;
break;
}
}
if (status != 0)
{
System.out.println(x);
count++;
}
status = 1;
x++;
}
}
}
Output of program:
Download Prime numbers program class file.