This post shows a Java program to display 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 ….

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

For example, if number is 8 then you just need to check till 4 (8/2) to see if it divides by any number or not. Same way if you have a number 15 you just need to check till 7 to see if it divides completely by any number or not. We'll use the same logic to write our program to display prime numbers up to the given upper range.

### Java program to print prime numbers

import java.util.Scanner; public class PrintPrime { public static void main(String[] args) { // take input from the user Scanner sc = new Scanner(System.in); System.out.println("Enter number till which prime numbers are to be printed: "); int num = sc.nextInt(); for(int i = 2; i <= num; i++){ if(isPrime(i)){ System.out.print(i + " "); } } } // Method to check if the passed number // is prime or not private static boolean isPrime(int num){ boolean flag = true; // loop from 2, increment it till number/2 for(int i = 2; i <= num/2; i++){ // no remainder, means divides if(num % i == 0){ flag = false; break; } } return flag; } }

__Output__

Enter number till which prime numbers are to be printed: 50 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47

Here scanner class is used to get input from the user.

- Refer
__How to read input from console in Java__to see other ways to get input from user.

That's all for this topic **Java Program to Display Prime Numbers**. If you have any doubt or any suggestions to make please drop a comment. Thanks!

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