Android: How to check whether a week has passed using Calendar class

Question

I want to check if a week has passed (using Calendar Class) and if it has then I need to print a message.

int lastCallDate = Calendar.SATURDAY;

int day = calender.get(Calendar.DAY_OF_WEEK);

if (day == lastCallDate + 7) {
    System.out.println("It's been a week");
} else { 
    System.out.println("It hasn't been a week");
}

Any suggestions or answers would be brilliant! Thanks.

you can achieve this by finding the day from the current date and then check it is sunday or not if sunday that means week had been passed. — Vishal Sharma, Nov 12 '18 at 21:01
A week since when? Since the last time you executed some task? Then you need to store the time you did that. — Ole V.V., Nov 13 '18 at 12:28
Possible duplicate of [Running task periodicaly(once a day/once a week)](https://stackoverflow.com/questions/8615543/running-task-periodicalyonce-a-day-once-a-week) — Ole V.V., Nov 13 '18 at 12:29

Sari Masri · Accepted Answer · 2020-05-26T08:31:02.613

1

if (day %lastCallDate ==0){
        System.out.println("It's been a week");

} else {

         System.out.println("It hasn't been a week");
}

edited May 26 '20 at 08:31

answered Nov 12 '18 at 21:00

Sari Masri

206
1
10

Hi @Sari Masri, thanks for the answer! What does "%" do? – Nov 12 '18 at 21:02
it will return Number of days left so if it the last day 7%7 will be zero – Sari Masri Nov 12 '18 at 21:06
1

So assuming `day` is in the interval 1–7 inclusive, it’s technically the same as `if (day == Calendar.SATURDAY)`, only harder to decipher? (And if `lastCallDate` was `MONDAY`, that is, 2, the result would be completely nonsensical, I’m afraid.) – Ole V.V. Nov 13 '18 at 15:07
@OleV.V., thanks for the explanation! How would you do it? – Nov 13 '18 at 15:36
@magicmass I’d either use the linked original question or like `LocalDate.now(ZoneId.of("Europe/Rome")).getDayOfWeek().equals(DayOfWeek.SATURDAY)`. With the reservation that I’m not sure I have understood the requirement from the question. – Ole V.V. Nov 13 '18 at 15:47

score 0 · Answer 2 · answered Nov 12 '18 at 21:11

At first you can store the first date as a UNIX timestamp. Then you can compare the current timestamp in seconds with the old, first saved timestamp whenever you want to check if 7 days past or not like below.

Calendar cal = Calendar.getInstance(Locale.getDefault());
long firstTimestampInSec = cal.getTimeInMillis() / 1000;

Then you can compare by looking if 604800 seconds past or not.

Calendar cal = Calendar.getInstance(Locale.getDefault());
long currentTimestampInSec = cal.getTimeInMillis() / 1000;
int oneWeekAsSec = 604800;

long firstTimestampInSec = getOldStoredTimestamp(); //First stored timestamp as seconds
if(currentTimestampInSec >= firstTimestampInSec + oneWeekAsSec){
    System.out.println("It's been a week");
}
else{
    System.out.println("It hasn't been a week");
}

Hi @Erdem Savasci, thanks for the answer. What’s “getOldStoredTimeStamp”? Where did you call it from? — , Nov 13 '18 at 14:47
Hi @magicmass. I just wrote it as an example. You can store the timestamp second value in many ways. For example in Android, you can use SharedPreferences as a key-value holder. Then you can write a method like "getOldStoredTimeStamp" to return the old timestamp value and compare it with the current value. — Erdem Savasci, Nov 13 '18 at 15:26

Android: How to check whether a week has passed using Calendar class

2 Answers2