Prime number program in Java

In this section you will learn how to check whether a given number is prime or not. We are performing looping operation on it for checking a number is prime or not.

What is prime number?

A number that is divisible only by itself and 1 is called prime number.

Example of prime number:

2, 3, 5, 7, 11, 13, 17 etc.

What is scanner function?

Scanner function is use to take the input from user in java.

How program will work?

• First import the scanner package at top of program.
• Second initialize three integer variable like (n, i, p).
• Assign the default value to "p" variable like p=0.
• Now perform looping operation on it.
• Finally show the result on output screen.

Program of prime number in Java

	import java.util.Scanner;

	class PrimeNumber
	{
		public static void main(String arg[])
		{
			int n,i,p=0;
			Scanner sc = new Scanner(System.in);
			System.out.println("ENTER A NUMBER:- ");
			n = sc.nextInt();
			for(i=2;i<=n/2;i++)
			{
				if(n%i==0)
				{
					p++;
					break;
				}
			}
			
			if(p==0 && n!= 1)
			{
				System.out.println(n+" IS PRIME NUMBER.");
			}
			else
			{
				System.out.println(n+" IS NOT A PRIME NUMBER.");
			}
		}
	}

Output:

	ENTER A NUMBER:- 5
	5 IS PRIME NUMBER.