Android 30 Days From Todays Date

Question

I need my application VIP feature to expire 30 days from today, I will store the current date in the application config. How will I check if the VIP feature has expired ? I don't mind if the user changed the clock back and the app works.

When user Activate a VIP features

mCurrentUser.setVip();
mCurrentUser.SaveInBackgroud();

// in want to also set StartDate and EndDate

Then to verify if the date saved in mCurrentUser endDate is igual to today

// set user to no VIP! like

mCurrentUser.setNoVip();
mCurrentUser.SaveInBackgroud();

Answer 1

You can get date after 30 days from given date by following method.

Calendar c = Calendar.getInstance();
    c.setTime(startDate);
    c.add(Calendar.DATE, 30);
Date expDate = c.getTime();

After that you can compare both dates.

if(startDate.after(expiate)){
   // Your time expired do your logic here.
}

if true then time is expired.

Answer 2

You should not store such information locally at all in this case. Instead, add field "activationDate" in Users table. Then do query for it and then do calculations locally.

Answer 3

If you want it to expire exactly on the second in 30d he started the vip, you can use this:

to start the timer:

SharedPreferences.editor editor1= getSharedPreferences("vipexpire", MODE_PRIVATE).edit();

                    editor1.putInt("starttime", (int) System.currentTimeMillis() / 1000);
                    editor1.apply();

in onCreate of your mainActivity, to check every time user opens app if the time is over:

SharedPreferences vipTimer= getSharedPreferences("vipexpire", MODE_PRIVATE);
int startTime= vipTimer.getInt("starttime", 0);
int currentTime = System.currentTimeMillis() / 1000;
int timeofVip= currentTime - startTime; //calculate the time of his VIP-being time
if (timeofVip>= 2592000)  //2592000 is 30 days in seconds
{
//30 days over, update user to non-vip
}

This method is also nice to have when storing the timestamp on a server or if you want to have an accurate countdown displayed in your app!