ListPaginatorPages

/*Вывод:
-> 1 <- | 2 | 3 | 4 | 5
1 | -> 2 <- | 3 | 4 | 5
1 | 2 | -> 3 <- | 4 | 5
2 | 3 | -> 4 <- | 5 | 6
3 | 4 | -> 5 <- | 6 | 7
4 | 5 | -> 6 <- | 7 | 8
5 | 6 | -> 7 <- | 8 | 9
6 | 7 | -> 8 <- | 9 | 10
7 | 8 | -> 9 <- | 10 | 11
8 | 9 | -> 10 <- | 11 | 12
9 | 10 | -> 11 <- | 12 | 13
10 | 11 | -> 12 <- | 13 | 14
11 | 12 | -> 13 <- | 14 | 15
12 | 13 | -> 14 <- | 15 | 16
13 | 14 | -> 15 <- | 16 | 17
14 | 15 | -> 16 <- | 17 | 18
15 | 16 | -> 17 <- | 18 | 19
16 | 17 | -> 18 <- | 19 | 20
16 | 17 | 18 | -> 19 <- | 20
16 | 17 | 18 | 19 | -> 20 <-*/


public final class ListPaginatorPages {

    public static void main(String[] args) {

        final int minPage = 1;
        final int maxPage = 20;

        final Page page = new Page(minPage, maxPage);

        for (int currentPage = minPage; currentPage <= maxPage; currentPage++) {
            page.apply(currentPage);
            System.out.println(page);
        }

    }

    private static final class Page {

        private final int minPage, maxPage;

        private final List<String> pages;

        Page(int minPage, int maxPage) {
            this.minPage = minPage;
            this.maxPage = maxPage;
            this.pages = new ArrayList<>();
            apply(minPage);
        }

        void apply(int currentPage) {

            if (!(currentPage >= this.minPage && currentPage <= this.maxPage)) {
                throw new IllegalArgumentException();
            }

            this.pages.clear();

            int minBorder = this.minPage, maxBorder = this.maxPage;

            while ((maxBorder - minBorder) != 4) {

                if ((minBorder < (currentPage - 2))) {
                    minBorder++;
                }

                if ((maxBorder > (currentPage + 2))) {
                    maxBorder--;
                }

            }

            for (int i = minBorder; i <= maxBorder; i++) {
                this.pages.add(i == currentPage ? String.format("-> %d <-", i) : Integer.toString(i));
            }

        }

        @Override
        public String toString() {
            return String.join(" | ", this.pages);
        }
    }

}