## Java Program – Check Prime Number

In this tutorial, we shall check if a number is prime or not.

You can use either while loop statement or for loop statement to find whether the given number is prime number or not.

### Algorithm

1. Start.
2. Read a number `N` from user.
3. Initialize `i` with 2.
4. If `i` is less than `N/i`, continue with next step, else go to step 7.
5. Check if `i` is a factor of `N`. If `i` is a factor of `N`, `N` is not prime, return false. Go to step 8.
6. If `i` is not a factor, increment `i`. Go to step 4.
7. Return `true`.
8. End.

### Java Program

In the following program, we shall write a function isPrime(), using the above algorithm. This function takes a number as argument, then check if the number is prime or not, and returns a boolean value. The function returns true if the number is prime, else it returns false.

Example.java

```/**
* Java Program - Check if Number is Prime Number
*/

public class Example {

public static void main(String[] args) {
System.out.println("Is 32 prime : "+isPrime(32));
System.out.println("Is 41 prime : "+isPrime(41));
}

public static boolean isPrime(int num) {
for(int i = 2; i <= num/i; ++i) {
if(num % i == 0) {
return false;
}
}
return true;
}
}```

Run the above program, and you shall get the following output in the console.

Output

```Is 32 prime : false
Is 41 prime : true```

### Conclusion

In this Java Tutorial, we learned how to write a Java Program to check if a given number is prime of not.