OMG bro,you show me a new method to play this!That's so interesting!

Almost. If itemCount could be zero, then that fails. Use

return (itemCount + itemsPerPage - 1) % ItemsPerPage + 1;

I don't remember if zero is allowed in the statement, but it should just be a habit in Java, C and C++ to avoid negative arguments to %.

Wow, You have just shown me that simple task can have awesome and unobvious solutions :)

It should handle the edge cases, e.g. zero page size (itemsPerPage)

no need for else statemens if you return before anyway

Hi @steffan153, I'm a beginner in java and I've never seen "<<", could you explain ? The mentioned doc didn't enlighten me a lot... Thanks :)

agreed! but good readability though

The last line at pageItemCount should be

return (itemCount - 1) % itemsPerPage + 1;

Ideally it should be something like this:
int remainingPages = itemCount() % itemsPerPage;

if(remainingPages == 0 || pageIndex < pageCount() - 1) return itemsPerPage;
else return remainingPages;

I noticed too, this solution will fail for scenarios when itemsPerPage completely divides totalPages

Bit shift is awesome. Nice job

That's a bitwise operator - the left bit shift.

What kind of magic is this?

Nice! That is Floyd's cycle-finding algorithm. Check out this wikipedia article for more info.