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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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