Java Program to check whether a Number is Prime or Not

In this tutorial, we will write a program to check whether the number is prime or not in java. Before that, you should have knowledge on the following topic in java.

• for loop
• if statement

Prime Number

A number is said to be a prime number if it is divisible by itself and 1. Example: 3, 5, 7, 11, 13, 17, 19, etc.

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Explanation:
We take a boolean variable isPrime and assigned it to be true. Then we take the user input and start a for loop for i = 2 end the loop for i less than half of the number entered. i will increase by 1 after each iteration.

Inside for loop, a temp variable will contain the remainder of each iteration. And then if statement will check for temp to be 0 that is if the remainder is zero, isPrime is set to false. If isPrime is true, the number is Prime number else not.

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Java Program to check whether a Number is Prime or Not

source code: Java Program to check for the prime number.

 //check for the prime Number

 import java.util.Scanner;
 public class PrimrNumberCheck
 {
   public static void main(String args[])
   {
     int temp;
     boolean isPrime = true;
     Scanner scan = new Scanner(System.in);

     System.out.print("Enter any number: ");

     int num = scan.nextInt();
     scan.close();

     for (int i = 2; i <= num / 2; i++)
     {
       temp = num % i;
       if (temp == 0)
       {
         isPrime = false;
         break;
       }
     }

     if (isPrime)
       System.out.println(num + " is a Prime Number"); //If isPrime is true 
     else
       System.out.println(num + " is not a Prime Number"); //If isPrime is false 
   }
 }

Output:

Enter any number: 13
13 is a Prime Number

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