如何定位列表中的每个第n个元素，但仅在3个元素之后

Question

How can I write a formula for this expression:

boolean showAd = (position == 3 || position == 11 || position == 19 || position == 27 || position == 35 || position == 43|| position == 51);
        if (showAd) {.....

I tried position % 8 ==0 but this doesnt produce the same sequence as above

Answer 1

Replace

position % 8 ==0

by

position % 8 == 3

Answer 2

The line

boolean showAd = (position == 3 || position == 11 ||
    position == 19 || position == 27 || position == 35 
    || position == 43|| position == 51);

will be similar to

boolean showAd = (position - 3) % 8 == 0 // Note the parentheses

// (3 - 3) = 0 % 8 = 0
// (11 - 3) = 8 % 8 = 0
// (19 - 3) = 16 % 8 = 0
// (27 - 3) = 24 % 8 = 0
// ...

But is not necessary to store the boolean value in a separate variable (unless you will use it later):

if ((position - 3) % 8 == 0) {
   ...
}