Java Code Example to Check Prime Number

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Here is an example of Java code to check if a given number is a prime number or not:

public class PrimeNumber {
    public static void main(String[] args) {
        int n = 17;
        if (isPrime(n)) {
            System.out.println(n + " is a prime number");
        } else {
            System.out.println(n + " is not a prime number");
        }
    }

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

In this code, the main function initializes the variable n to 17 and then calls the isPrime function to check if it is a prime number. If the function returns true, then the program prints a message saying that the number is prime, otherwise it prints a message saying that the number is not prime.

The isPrime function takes an integer n as input and returns a boolean value indicating whether n is a prime number or not. The function first checks if n is less than or equal to 1, which is not a prime number. Then, it uses a for loop to iterate from 2 to the square root of n, checking if n is divisible by any number in that range. If n is divisible by any number in the range, then it is not a prime number and the function returns false. Otherwise, the function returns true.

When this code is executed, it will output the message “17 is a prime number” to the console.

In conclusion, this Java code checks if a given number is a prime number using a for loop and the square root function. The code can be modified to take user input for the value of n or to output all prime numbers within a given range.

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