Java - Varargs|While(true)|Scanner - exiting infinite while loop

Before describing my issue, I would like to let you know that I am familiar with ArrayList, but I am curious how this works with varargs.

My problem is:
I can not exit the infinite loop with the input value zero (variable type is int) when I use varargs with scanner input.

I've tried:
to exit the infinite loop with a simple "if the input number == 0 --> break from the loop". I don't understand why this doesn't work. What should I change on the code?

Some code I've tried:

static Scanner scanner = new Scanner(System.in);

public static void main(String[] args) {
    createIntArray();
}

public static void createIntArray(int... numbers) {
    System.out.println("Enter numbers:");
        while (true) {
            for (int i = 0; i < numbers.length; i++) {
                numbers[i] = scanner.nextInt();
                if (numbers[i] == 0) {
                    break;
                }
            }
    }
}

Adding some more background information to my question:
I read a Java book where the lesson about single dimensional arrays ends with an unsolved exercise question about reading the integers between 1-100 and counting the occurrences. The input should end with 0. Thus, the arrays length is not defined. In the single dimensional arrays lesson the varargs is described as an array with variable number of arguments. I understand that the number of arguments is not set. I was thinking I could use varargs to create array with undefined length using the Scanner method.
Now knowing that the initial length of the array created by the varargs is zero, I am not sure where the length could be manipulated if I would like to use the Scanner method to increase the arrays length.
I know that ArrayList is more flexible and could be use to solve this problem, but having a question at the end of the single dimensional arrays lesson where one of the task is to create undefined length array makes me thing this could be done with a single dimensional array too.

Your problem has nothing to do with varargs (aslo known as "variable arity methods").

Your problem is that, in:

static Scanner scanner = new Scanner(System.in);

public static void main(String[] args) {
    createIntArray();
}

public static void createIntArray(int... numbers) {
    System.out.println("Enter numbers:");
    
    while (true) {
        for (int i = 0; i < numbers.length; i++) {
            numbers[i] = scanner.nextInt();
            if (numbers[i] == 0) {
                break;
            }
        }
    }
}

the for loop is never entered, and therefore, you never break out from the while.

The reason why for loop's body is never executed is, that i < numbers.length always evaluates to 0 < 0, which is false. So, your while loop goes on infinitely, with never entering into the for.

Varargs (variable arity method)

You do not ask the question, which might (I think - it perfectly well may) strike more attention:

• Why does my code compile?

but you do mention "varargs", and I will use this chance to let you know a bit more details on that topic.

Type...varargs and Type[] varargs compile to the same code.

There is a little syntactical catch though:

OCP Java SE 8 Preparation text-book (Scott Selikoff, Jeanne Boyarsky):
>Invocation of the method with variable length parameter should happen with literally - variable number of elements [0..n], whereas invocation of the method of array type parameter, must happen by providing an array as an argument.

Effective Java, 3rd Edition (by Joshua Bloch):
>The varargs facility works by first creating an array whose size is the number of arguments passed at the call site, then putting the argument values into the array, and finally passing the array to the method.

That is why your code compiles. If you have Type...varargs parameter in your method, you can omit the corresponding explicit argument at all (that is what you are doing), and the corresponding (to above definitions) implicit value will be assigned to that parameter.

You're implicitly passing an empty array to createIntArray. Therefore, the for loop doesn't execute (because numbers.length is 0), and the break statement is never reached.

Instead of passing an array to the method, you could return one from it:

public static void main(String[] args) {
    int[] numbers = createIntArray();
}

public static int[] createIntArray() {
    System.out.println("Enter numbers:");
    List<Integer> list = new LinkedList<>();
    while (true) {
        int num = scanner.nextInt();
        if (num == 0) {
            break;
        }
        list.add(num);
    }
    return list.stream().mapToInt(Integer::intValue).toArray();
}