Dynamic Arrays in Java? Using ArrayList vs int[] array = new int[n]

Question

So I'm confused why this isn't considered a dynamic array?

public static void main(String[] args) {
    Scanner in = new Scanner (System.in);
    int n = in.nextInt();
    int[] array = new int[n];
    for ( int i = 0; i < n; i++) {
        array[i] = i;
    }

    for ( int i = 0; i < n; i++) {
        System.out.print(array[i]);

Should I be using ArrayList instead here or is this usage ok?

In general arrays in Java are dynamically allocated, but have fixed size (unless you reallocate). — mkzh
– mkzh, Commented Jul 18, 2016 at 1:05
When you create an array, you specify (declare) the size of it at the start. With a list you do not have to do that. That is the main difference. If you later decide that you want more than n elements in your array, it is not possible, but with a list it would be (of course, a list doesn't do magic, but you get the point). — RaminS
– RaminS, Commented Jul 18, 2016 at 1:05

Thihara · Accepted Answer · 2016-07-18 01:31:34Z

5

Java doesn't have dynamic arrays. Once an array has been created it's size cannot be changed.

ArrayList uses an internal array for storage, but it resizes the array internally so you don't have to worry about it.

Internally of course it simply creates a new, larger array and copies things over when it needs more space.

As for if your usage of array is OK, for the given scenario, it is. If your array content size is unknown or if it can change, then switch to ArrayList rather than doing the resizing yourself.

answered Jul 18, 2016 at 1:31

Thihara

6,9692 gold badges33 silver badges58 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Dynamic Arrays in Java? Using ArrayList vs int[] array = new int[n]

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related