# Java program to check whether number is prime or not

Let’s learn java program to check whether a number is prime or not.

## Java program to check whether number is prime or not

Prime numbers are those numbers which cannot be divided by other numbers than 1 or itself. Example : 2, 3, 5, 7, 11, 13, 17….

NOTE: 0 and 1 are not prime numbers. 2 is only even prime number.

Here’s the java code to check if number is prime or not using if else.

```public class PrimeNumberInJava
{
public static void main(String[] args)
{
int a, b = 0, flag = 0;
int number = 66;
b = number / 2;
if(number == 0 || number == 1)
{
System.out.println(number + " is not prime number");
}
else
{
for(a = 2; a <= b; a++)
{
if(number % a == 0)
{
System.out.println(number + " is not prime number.");
flag = 1;
break;
}
}
if(flag == 0)
{
System.out.println(number + " is prime number.");
}
}
}
}

```

Output:

program to check whether the given number is prime or not using while loop

Here’s the program to check whether a number is prime or not using for loop using while loop.

```import java.util.Scanner;
{
public static void main(String[] args)
{
boolean checkPrime = true;
Scanner sc = new Scanner(System.in);
int number = sc.nextInt();
int a = 2;
while(a <= number / 2)
{
if(number % a == 0)
{
checkPrime = false;
break;
}
a++;
}
if(checkPrime)
{
System.out.println(number + " is a prime number.");
}
else
{
System.out.println(number + " is not a prime number.");
}
sc.close();
}
}

```

Output: