如果您问的是“如何计算4x8Map中第12个对象的位置”，则算法如下：
（我假设向量2包含int，int作为x，y位置，0，0是原点，我们从1开始计算分幅）：

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 + ")";
        }
    }
}

输出：

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