# Prime number java

Hi guys!! Welcome to flower brackets blog. Today we are going to learn prime number java.

A prime number is a number that is greater than one and divided by itself. Prime numbers are those numbers which cannot be divided by other numbers than 1 or itself.

Also read – palindrome number in java

Example : 2, 3, 5, 7, 11, 13, 17….

In the example for loop determines if given number is prime or not. In this for loop condition is checked if number is divisible by any number in range number / 2.

We set “temp” to true and break out of for loop. Hence it is a prime number. If number is not divisible “temp” is false and number is prime number.

Here’s java program to check whether a number is prime or not,

```public class JavaPrimeNumber
{
public static void main(String[] args)
{
int a, b = 0, temp = 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.");
temp = 1;
break;
}
}
if(temp == 0)
{
System.out.println(number + " is prime number.");
}
}
}
}

```

Output :

66 is not prime number.

Similarly we can execute using a while loop,

```import java.util.Scanner;

{
public static void main(String[] args)
{
boolean checkPrime = false;
Scanner sc = new Scanner(System.in);
System.out.println("Please enter any number : ");
int number = sc.nextInt();
int a = 2;
while(a <= number / 2)
{
if(number % a == 0)
{
checkPrime = true;
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:

Please enter any number : 50
50 is not a prime number.

Now let’s see java program to check prime number using method,

```import java.util.Scanner;

public class JavaPrimes
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.print("Please enter a number : ");
int num = sc.nextInt();
if(checkPrime(num))
{
System.out.println(num + " is a prime number.");
}
else
{
System.out.println(num + " is not a prime number.");
}
sc.close();
}

public static boolean checkPrime(int number)
{
if(number <= 1)
{
return false;
}
for(int a = 2; a < Math.sqrt(number); a++)
{
if(number % a == 0)
{
return false;
}
}
return true;
}
}

```

Output:

Please enter a number : 36
36 is not a prime number.