Java Program To Check Whether Number Is Prime Or Not

Chapter: Miscellaneous Last Updated: 08-09-2017 16:30:08 UTC


            /* ............... START ............... */
public class JavaNumberIsPrimeOrNot {

	public static void main(String[] args) {

		int num = 17;
		boolean flag = false;
		for (int i = 2; i <= num / 2; ++i) {
			if (num % i == 0) {
				flag = true;

		if (!flag)
			System.out.println(num + " is a prime number.");
			System.out.println(num + " is not a prime number.");
                /* ............... END ............... */


17 is a prime number.


  • A prime number is a number which is divisible by only two numbers: 1 and itself.
  • In the above program, for loop is used to determine if the given number num is prime or not.
  • Inside the for loop, we check if the number is divisible by any number in the given range (2..num/2). If it is, flag is set to true and we break out of the loop. This determines num is not a prime number.
  • If num isn't divisible by any number, flag is false and num is a prime number.


Check Whether Number Is Prime Or Not, Java, Interview

Similar Programs Chapter Last Updated
How To Create A Git Repository | Git repository commands Miscellaneous 31-07-2021
Currency Formatter In Java | How To Format Currency In Java Miscellaneous 19-07-2021
Factory Design Pattern In Java Miscellaneous 11-05-2021
Data Types In Java Miscellaneous 09-06-2018
Java Program To Find Largest Element Of Array Miscellaneous 21-09-2017
Java Program To Find Power Of Number Using For Loop Miscellaneous 29-08-2017
Java Program To Find LCM Of Two Numbers Miscellaneous 29-08-2017
Java Program To Find GCD Of Two Numbers Miscellaneous 29-08-2017
Java Program To Check Whether An Alphabet Is Vowel Or Consonant Miscellaneous 25-08-2017
Java Program To Find ASCII Value Of Character Miscellaneous 25-08-2017
Java Object HashCode Method Miscellaneous 02-08-2017
Java Builder Design Pattern Example Miscellaneous 06-06-2017
Java Factory Design Pattern Example Miscellaneous 06-06-2017
Java Program To Print ASCII Values Miscellaneous 06-04-2017
Java Program To Find HCF LCM Of Two Numbers Miscellaneous 22-09-2018
Java String Array Iteration Miscellaneous 31-03-2017
Java Array Size Miscellaneous 30-03-2017
Java Integer toString Miscellaneous 30-03-2017
Java Sort Array Using Arrays.sort() Miscellaneous 28-03-2017
Java Print Array Using Arrays.toString Miscellaneous 28-03-2017
Java Nested Interface Miscellaneous 25-03-2017
Java Static Nested Class Miscellaneous 25-03-2017
Packages In Java Miscellaneous 24-03-2017
Java Strictfp Keyword Miscellaneous 24-03-2017
Java Call By Reference Miscellaneous 23-03-2017
Java Call By Value Miscellaneous 23-03-2017
Java Unboxing Example Miscellaneous 23-03-2017
Java Autoboxing Example Miscellaneous 23-03-2017
Java Format Currency Miscellaneous 15-02-2017
Java String To BigDecimal Conversion Miscellaneous 15-02-2017

1 2 3 4 5