Java - Get array of name of day for current week

Question

What I am looking for is to create an array of the days of the week in java, starting from yesterday and go up to six days time as such

 String daysWeek[] = { "Yesterday", "Today", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday"};

The first two elements of the array I want to return as Yesterday and Today.

At first this seemed like an easy task by using

currentDay = Calendar.getInstance().get(Calendar.DAY_OF_WEEK);

String daysList[] = {"Sunday", "Monday", "Tuesday", "Wednesday",
            "Thursday", "Friday", "Saturday"};

String daysWeek[] = {"Yesterday", "Today", daysList[currentDay], daysList[currentDay+1], ...};

A note on above daysList[currentDay] will return tomorrow since the array of daysList starts at 0 i.e if currentDay = 3 which says today is Tuesday then this will be daysList[2].

But my problem lies in that if the currentDay is 7 which implies today is Saturday then currentDay+1 which is tomorrow will be the eighth element of the array which doesn't exist.

Is there any which in I can loop round my numbers that if today is Wednesday or later then once currentDay + x > 7, set currentDay back to 1?

This all takes place in one method as is called getDaysList(currentDay) which returns the daysWeek[] array.

Answer 1

A function of use to you here is the modulo (%) operator.

Basically, what the modulo operator does is take the remainder of the division, which is exactly what you want. (Remember back in fourth grade when "9 / 2" wasn't 4.5, but 4 remainder 1? This is that remainder part.)

So instead of having:

days[currentDay + x]

Use:

days[(currentDay + x) % 7]

Quick example on values returned by the modulo operator:

 0 % 7 = 0   (0 / 7 = 0 R0)
 1 % 7 = 1   (1 / 7 = 0 R1)
 6 % 7 = 6   (6 / 7 = 0 R6)
 7 % 7 = 0   (7 / 7 = 1 R0)
 8 % 7 = 1   (8 / 7 = 1 R1)
15 % 7 = 1   (15 / 7 = 2 R1)