java- How to add 7 days to a default date?

Question

I have a current date in Java like below:

String currentDate = CoreUtil.parseDate(new Date());

This returns the date for today in the form 2019-03-26.

I declared another date so that it should automatically add 7 days to the current date like below:

String defaultendDate=CoreUtil.parseDate(new Date()); + 7 days //example

So the defaultEnddate should be 2019-04-03

How would I accomplish this as I don't want to use any simple date formatter?

Also, I would like to store the date as it is in String for reasons and secondly, I only want date, not the time. I am not using Java 8 as well, so I can't really use LocalDate library here.

You simply can store the final date in whatever representation you want. Your "CoreUtil.parseDate" should transfer the "+7 date" to a String anyways, doesn't it? — SirFartALot, Mar 26 '19 at 07:24
you can use joda time lib https://www.joda.org/joda-time/. it contains many useful methods. — JHDev, Mar 26 '19 at 09:44

MC Emperor · Accepted Answer · 2019-03-26T10:04:52.967

4

LocalDate is perfect for this job:

LocalDate.now().plusDays(7);

You can get your string representation with

.format(DateTimeFormatter.ISO_DATE);

If you're not able to use Java 8, then you have a few options:

Use the ThreeTen-Backport, which backports most functionality of the Java 8 JSR-310 API, normally available in the java.time package. See here for details. This package is available in Maven Central.
You can also use Joda Time. The peculiar thing is that these two projects have almost the same layout of their websites.
If you're otherwise not able to use ThreeTen-Backport or Joda Time, you can use this:
```
Calendar c = GregorianCalendar.getInstance();
c.add(Calendar.DATE, 7);

String s = new SimpleDateFormat("yyyy-MM-dd")
    .format(c.getTime());
```
Warning
Many things are wrong with the old Date and Time API, see here. Use this only if you have no other option.

edited Mar 26 '19 at 10:04

answered Mar 26 '19 at 07:19

MC Emperor

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Bingo, this is the modern solution. – Basil Bourque Mar 26 '19 at 07:20
Does this take the form of `YYYY-MM-DD`? – Daredevil Mar 26 '19 at 07:21
Although, I can't seem to find `LocalDate` on my library function. Can't import it. I believe `LocalDate` is for Java 8? Sadly, I am not using java 8 – Daredevil Mar 26 '19 at 07:21
@Daredevil See the edit I made, directing you to the back-port. – Basil Bourque Mar 26 '19 at 07:26
Just a question, is `(Calendar.Day_OF_Month,7)` works as well? – Daredevil Mar 26 '19 at 10:01

score 1 · Answer 2 · answered Mar 26 '19 at 07:17

1

Use Calendar.

 Calendar cal = Calendar.getInstance();
 cal.add(Calendar.DAY_OF_MONTH, 7);
 Date defaultEndDate = cal.getTime();

answered Mar 26 '19 at 07:17

vavasthi

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Can I use `String defaultEndDate`? – Daredevil Mar 26 '19 at 07:18
You have to do `.toString()` on it. – vavasthi Mar 26 '19 at 07:19
1

These terrible classes were supplanted years ago by the modern *java.time* classes years ago with the adoption of JSR 310. Suggesting their use in 2019 is poor advice. – Basil Bourque Mar 26 '19 at 07:19
why do you use `getTime`? I only want the date. – Daredevil Mar 26 '19 at 07:25
2

Look at `SimpleDateFormat` to convert it to whatever string you want. – vavasthi Mar 26 '19 at 07:26
So how does it look like in the end? I don't follow – Daredevil Mar 26 '19 at 07:28

MS90 · Answer 3 · 2019-03-26T07:52:23.580

1

Something like

LocalDate.now().plusWeeks(1);

would also do the cause.

Please, bare in mind using Java 8 Date/Time API for any operations with dates and times. as it addresses shortcomings of old Date and Calendar regarding thread safety, code design, time-zone logic and other.

UPDATE:

If you must use old Date/Time API, following code would suffice:

Date date = new Date();
Calendar calendar = Calendar.getInstance();  
calendar.setTime(date);  
calendar.add(Calendar.DAY_OF_MONTH, 7);
System.out.println("Adding seven days: " + calendar.getTime());
date = calendar.getTime();
//your code
String currentDate = CoreUtil.parseDate(new Date());

edited Mar 26 '19 at 07:52

answered Mar 26 '19 at 07:37

MS90

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I can't use LocalDate because it's on Java 8 – Daredevil Mar 26 '19 at 07:42
OK, check the code for old date/time api. @Daredevil – MS90 Mar 26 '19 at 07:55

score 0 · Answer 4 · answered Mar 26 '19 at 07:36

0

*
String dt = new SimpleDateFormat("yyyy.MM.dd").format(new Date());  // Start date
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        Calendar c = Calendar.getInstance();
        c.add(Calendar.DATE, 7);  // number of days to add
        dt = sdf.format(c.getTime());  // dt is now the new date
        System.out.println(dt);

*
Use java.util.Date try this one

answered Mar 26 '19 at 07:36

Kamal Kumar

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How does this return `YYYY-mm-DD`? – Daredevil Mar 26 '19 at 07:43
SimpleDateFormat is used to format and parse dates in Java. You can create an instance of SimpleDateFormat with a date-time pattern like yyyy-MM-dd HH:mm:ss, and then use that instance to format and parse dates to/from string – Kamal Kumar Mar 26 '19 at 07:49

java- How to add 7 days to a default date?

4 Answers4