lock - 5 months ago 70x

Java Question

Given today's time e.g. 2:24PM, how do I get it to round to 2:30PM?

Similarly if the time was 2:17PM, how do I get it to round to 2:15PM?

Answer

You will need to use modulo to truncate the quarter hour:

```
Date whateverDateYouWant = new Date();
Calendar calendar = Calendar.getInstance();
calendar.setTime(whateverDateYouWant);
int unroundedMinutes = calendar.get(Calendar.MINUTE);
int mod = unroundedMinutes % 15;
calendar.add(Calendar.MINUTE, mod < 8 ? -mod : (15-mod));
```

As pointed out by EJP, this is also OK (replacement for the last line, only valid if the calendar is lenient):

```
calendar.set(Calendar.MINUTE, unroundedMinutes + mod);
```

If you want to be exact, you will also have to truncate the smaller fields:

```
calendar.set(Calendar.SECOND, 0);
calendar.set(Calendar.MILLISECOND, 0);
```

You can also use DateUtils.truncate() from Apache Commons / Lang to do this:

```
calendar = DateUtils.truncate(calendar, Calendar.MINUTE);
```

Source (Stackoverflow)

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