How do i get a vector2 from a list index?

Question

Let's say I have an ArrayList with 32 objects in it, forming a 2d TileMap of 4x8.

And I want to get the position of 12th object. how do i get the vector2? And remember, objects doesn't have a vector2, i want to get positions from the index.

Answer 1

If what you are asking is "how do I calculate the position of eg. the 12th object in a 4x8 map" then the algorithm is something like this:

(I assume vector2 is something that holds int, int as x, y positions and 0, 0 is the origin and we count tiles starting on 1):

public class Test {

    private static final int xDimension = 4;

    public static void main(String[] args) {
        System.out.println(getPosition(1));
        System.out.println(getPosition(3));
        System.out.println(getPosition(4));
        System.out.println(getPosition(5));
        System.out.println(getPosition(12));
        System.out.println(getPosition(32));
    }

    public static Vector2 getPosition(int n) {
        int y = (n - 1) / xDimension;
        int x = (n - 1) % xDimension;
        return new Vector2(x, y);
    }

    public static class Vector2 {
        int x, y;

        public Vector2(int x, int y) {
            this.x = x;
            this.y = y;
        }

        @Override
        public String toString() {
            return "(" + x + ", " + y + ")";
        }
    }
}

Output:

(0, 0)
(2, 0)
(3, 0)
(0, 1)
(3, 2)
(3, 7)