In Previous post Check whether a number is prime or not we learnt how to check whether given number is prime number or not and this post is all about **Java Program to displaying prime numbers**

As we know that a number is a prime number if it is a natural number greater than 1 and it can be divided either by 1 or by the number itself. As example- 2, 3, 5, 7, 11, 13, 17,19,23..….

For checking if a number is prime or not you have to run a loop starting from 2 till number/2 to check if number has any divisor or not.

**As example –** If number is 10 then you just need to check till 5 (10/2) to see if it divides by any number or not. Same way if you have a number 25 you just need to check till 12(25/2) to see if it divides completely by any number or not. We’ll use the same concept/logic to write our java program to check for prime number.

#### Note: You should note that 0 and 1 are not prime numbers. We have number 2 is the only even prime number because all the other even numbers can be divided by 2.

Let’s write a **Java Program to displaying prime numbers**

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package com.kkjavatutorials.clients; import java.util.Scanner; /** * * @author KK JavaTutorials *Java Program to displaying prime numbers */ public class DisplayPrimeNumbersTest { public static void main(String[] args) { Scanner scanner = null; try { // Taking input from the user using scanner scanner = new Scanner(System.in); System.out.println("Please enter number till which you want prime numbers to be printed:"); int number = scanner.nextInt(); if(number<=1){ System.out.println("Enter valid number"); return; } for (int i = 2; i <=number; i++) { if(isPrimeNumber(i)){ System.out.print(i+" "); } } } catch (Exception e) { e.printStackTrace(); } finally { if (scanner != null) scanner.close(); } } private static boolean isPrimeNumber(int number) { boolean flag = true; // for loop start from 2 and increment it till number/2 for (int i = 2; i <=number/2; i++) { // if no remainder found means we get divider if (number % i == 0) { flag = false; break; } } return flag; } } |

**Output of this program: **

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Please enter number till which you want prime numbers to be printed: 100 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 |

That’s all about **Java Program to displaying prime numbers**

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