Need to find the difference between two dates in days and hours form

Question

I want to find the difference in days and hours between 2 dates. I looked through all the posts and majority of the posts only showed how to find it in days. My assignment required us to find the difference in days and hours

Date date = new Date();
String due_date = DateFormat.format("dd-MMM-yy", getTask.getDueDate()).toString();

long diff = getTask.getDueDate().getTime() - date.getTime();
long seconds = diff / 1000;
long minutes = seconds / 60;
long hours = minutes / 60;
long days = hours / 24;

I've done the coding above. The due date is set through date picker and the date is the current date and time. I want them like for example, I set the due date to be 21-11-2019 00:00:00 and my current date and time is 21-11-2019 07:00:00 and the result to be '0 days 7 hours'.

Could the due date be all of (1) in the past (2) today and (3) in the future? — Ole V.V., Nov 20 '19 at 19:46

score 1 · Accepted Answer · answered Nov 20 '19 at 19:15

1

You've already calculated the days and hours. All you need to do is print something like this:

System.out.println(days + " days " + (hours % 24) + " hours");

In case you haven't seen it before, % is the modulus operator. It gives you the remainder after division.

answered Nov 20 '19 at 19:15

ᴇʟᴇvᴀтᴇ

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Thanks so much, I was looking for a really simple solution and this actually worked for my assignment. – Pepega Nov 21 '19 at 13:41
No problem. Can you upvote and accept the answer? – ᴇʟᴇvᴀтᴇ Nov 21 '19 at 14:04

Ole V.V. · Answer 2 · 2019-11-29T20:34:37.877

java.time and ThreeTenABP

Edit: revised the code after new information, and smoke tested.

the due date can be today or in the future.

    DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("dd-MMM-uu", Locale.ROOT);
    ZoneId zone = ZoneId.systemDefault();

    ZonedDateTime now = ZonedDateTime.now(zone);
    String dueDateString = "01-Dec-19";

    LocalDate dueDate = LocalDate.parse(dueDateString, dateFormatter);
    LocalDate today = now.toLocalDate();
    if (dueDate.equals(today)) {
        System.out.println("Due date is today");
    } else {
        // Count days from tomorrow and then hours until start of day tomorrow
        LocalDate tomorrow = today.plusDays(1);
        long days = ChronoUnit.DAYS.between(tomorrow, dueDate);

        ZonedDateTime startOfDayTomorrow = tomorrow.atStartOfDay(zone);
        long hours = ChronoUnit.HOURS.between(now, startOfDayTomorrow);

        System.out.println("Due date will be in " + days + " days " + hours + " hours");
    }

When I ran the code just now in my time zone (Europe/Copenhagen), the output was:

Due date will be in 1 days 2 hours

I am unsure whether this is the exact output that you wanted, but I hope that you can adjust the code to give you what you want.

For Android below API level 26 add the ThreeTenBackport library to your project and make sure to import the date and time classes from org.threeten.bp with subpackages.

Please give your formatter the correct locale depending on the language of your date string.

The classes Date, DateFormat and SimpleDateFormat are all poorly designed and long outdated, and java,time, the modern Java date and time API, is so much nicer to work with. Also you shouldn't hand calculate days and hours from milliseconds. It's more complicated than what you do in your code, errorprone and harf to read. Rely on well-proven library methods for such a task.

Original code:

    DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("dd-MMM-uu", Locale.ROOT);
    ZoneId zone = ZoneId.systemDefault();

    ZonedDateTime now = ZonedDateTime.now(zone);
    String dueDateString = "20-Nov-19";

    LocalDate dueDate = LocalDate.parse(dueDateString, dateFormatter);
    long days = ChronoUnit.DAYS.between(dueDate, now.toLocalDate());

    ZonedDateTime startOfToday = now.toLocalDate().atStartOfDay(zone);
    long hours = ChronoUnit.HOURS.between(startOfToday, now);

    System.out.println("Due date was " + days + " days " + hours + " hours ago");

Question: Doesn’t java.time require Android API level 26?

java.time works nicely on both older and newer Android devices. It just requires at least Java 6.

In Java 8 and later and on newer Android devices (from API level 26) the modern API comes built-in.
In non-Android Java 6 and 7 get the ThreeTen Backport, the backport of the modern classes (ThreeTen for JSR 310; see the links at the bottom).
On (older) Android use the Android edition of ThreeTen Backport. It’s called ThreeTenABP. And make sure you import the date and time classes from org.threeten.bp with subpackages.

Links

Oracle tutorial: Date Time explaining how to use java.time.
Java Specification Request (JSR) 310, where java.time was first described.
ThreeTen Backport project, the backport of java.time to Java 6 and 7 (ThreeTen for JSR-310).
ThreeTenABP, Android edition of ThreeTen Backport
Question: How to use ThreeTenABP in Android Project, with a very thorough explanation.

I tried it and this worked too. Thanks for suggesting this method to me! — Pepega, Nov 21 '19 at 13:45

Need to find the difference between two dates in days and hours form

2 Answers2

java.time and ThreeTenABP

Question: Doesn’t java.time require Android API level 26?

Links