# Print Prime Numbers in Java

In this post we will see couple of examples on how to print prime numbers in Java. A positive integer is called Prime Number when it is greater than 1 and divisible only with itself and by 1. Example: 2, 3, 5, 7, 11, 13, 17, 19 etc.,

## Print Prime Numbers using custom square root function:

``````package com.techstackjournal;
/**
*
* Program to print prime numbers within a given limit
*
*/
public static void main(String args[]) {
int limit = 200;
for (int n = 2; n <= limit; n++) {
System.out.format("%d ",n);
}
}
}
/**
* Checks if given number is Prime or not
*
* @param n
* @return
*/
private static boolean isPrimeNumber(int n) {
for (int i = 2; i <= squareRoot(n); i++) {
if (n % i == 0) {
return false;
}
}
return true;
}
/**
* Returns the square root of a number
*
* @param num
* @return
*/
private static double squareRoot(double num) {
double n2 = num / 2;
double n1;
do {
n1 = n2;
n2 = (n1 + num / n1) / 2;
} while (n1 - n2 != 0);
return n2;
}
}``````

## Prints Prime Numbers using Math class

``````package com.techstackjournal.java.basics;
/**
*
* Program to print prime numbers within a given limit
*
*/
public static void main(String args[]) {
int limit = 200;
for (int n = 2; n <= limit; n++) {
System.out.format("%d ", n);
}
}
}
/**
* Checks if given number is Prime or not
*
* @param n
* @return
*/
private static boolean isPrimeNumber(int n) {
for (int i = 2; i <= Math.sqrt(n); i++) {
if (n % i == 0) {
return false;
}
}
return true;
}
}``````