Why do arrays need a measurement set during determination?

Question

I'm just wondering why we can't just define something like this:

int[] arr = new int[];
arr[0] = 1;

Like the list, to automatically resize. I want to know why this is not possible, and we must set the size each time as follows:

int[] arr = new int[1];
arr[0] = 1;

Answer 1

List<T> resizing is based on creating a new array behind the scenes when necessary.

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Answer 5

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If you need a collection with dynamic size, there are others, such as the list you talked about.

What you can do is to delay the declaration of the size of the array:

int[] numbers;
numbers = new int[10];  
numbers = new int[20];