Unknown error

Hello, I am new to coding with only python and now some java experience. I am getting error’s in java coding that i have never seen and I can’t find anything on google to help me out well enough. The code I am providing below is not completed. I build my code in segments to help me find errors before completing.

the URL is:
Prime Directive

My code:

import java.util.ArrayList;

class PrimeDirective {

    public boolean isPrime(int number) {
        if (number <= 1) return false;
        ArrayList<Integer> newArray= new ArrayList();
        boolean trueOrFalse = true;

        for (int i = number-1; i > 1; i--) newArray.add(i);

        for (int i : newArray) {
            if (number % i == 0) {
              System.out.println(i);
              trueOrFalse = false;
        }
    }
    return trueOrFalse;
    }
    public static void main(String[] args) {

        PrimeDirective pd = new PrimeDirective();
        int[] numbers = {6, 29, 28, 33, 11, 100, 101, 43, 89};

        for (int i : numbers) {
            pd.isPrime(i);
        }
    }
}

The Error I am getting is:
Note: PrimeDirective.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

I have no idea what this wants from me now. Please let me know if anyone can provide assistance to this error and not to solving the Prime Directives class. Thank you!

An edit to my own post:
I ran a my a final copy of my code in another program and found no error’s (as far as i could see) and the list to be correct.

Please let me know if the code below works. Thank you.

import java.util.ArrayList;

class PrimeDirective {

    public boolean isPrime(int number) {
        if (number <= 1) return false;

        ArrayList<Integer> newArray= new ArrayList();
        boolean trueOrFalse = true;

        for (int i = number-1; i > 1; i--) newArray.add(i);

        for (int i : newArray) {
            if (number % i == 0) trueOrFalse = false;
        }
         return trueOrFalse;
    }

    public static void main(String[] args) {

        PrimeDirective pd = new PrimeDirective();
        int[] numbers = {6, 29, 28, 33, 11, 100, 101, 43, 89};
        ArrayList<Integer> primeNum= new ArrayList();
        ArrayList<Integer> notPrimeNum= new ArrayList();

        for (int i : numbers) {
            if (pd.isPrime(i) == true) {
                primeNum.add(i);
            }
            else if (pd.isPrime(i) == false){
                notPrimeNum.add(i);
            }
        }
        System.out.println("These numbers are prime: ");
        System.out.println(primeNum);
        System.out.println("These numbers are not prime: ");
        System.out.println(notPrimeNum);
    }
}

An error would mean it didn’t compile, it probably did.
If there are warnings then you would want to consider them.

Unrelated, please don’t put an if/loop’s body on the same line as the if/loop itself, it’s very difficult to read. The shape of the code is helpful in quickly figuring out what’s what. You might also include the curly braces even for single lines for consistency’s sake, that way the difference between one line and two lines is just the one line, which is the same difference as you get between two and three lines.

comparing booleans using == is redundant. the result of that will be boolean.