Convert String to date to calculate the difference

Question

I have 2 dates in a String format (ex. 2012-04-23, 2012-03-08), and I want to find the difference between them.

What is the best way to calculate that in Java?

I am just concerned with the date and not the time

Answer 1

If you are willing to add a third party jar to your project, then check the jodatime

• Convert string to date - DateTimeFormat

DateTimeFormatter formatter = DateTimeFormat.forPattern("dd/MM/yyyy HH:mm:ss");

DateTime dt = formatter.parseDateTime(your-string);

• Find the difference between them -interval

Interval interval = new Interval(time1, time2);

You also might want to check the difference between interval and duration which are concepts in jodatime lib

Answer 2

Use SimpleDateFormat to turn the strings into Date objects and use the getTime() method on Date to get the equivalent time in milliseconds. Take the difference between the two milliseconds values.

Answer 3

You can convert string to date using:

String dateString = "2012-04-23";
Date date = new SimpleDateFormat("yyyy-mm-dd").parse(dateString);

You can read about SimpleDateFormat further here.

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As to difference between two dates, you can calculate it in milliseconds with:

int milliseconds = dateOne.getTime() - dateTwo.getTime();

getTime() returns the number of milliseconds since January 1, 1970.

To convert it in days, use:

int days = milliseconds / (1000 * 60 * 60 * 24)

Answer 4

You may want to you DateFormat, Date and Calendar combination as below:

    DateFormat dFormat = new SimpleDateFormat("yyyy-MM-dd");
    Date date1 = dFormat.parse("2012-04-23");
    Date date2 = dFormat.parse("2012-03-08");
    long timeDifInMillis = date1.getTime() - date2.getTime();

    Date dateDiff = new Date(timeDifInMillis);
    Calendar diffCal = Calendar.getInstance();
    diffCal.setTime(dateDiff);
    System.out.println("Days="+diffCal.get(Calendar.DAY_OF_MONTH));
    System.out.println("Months="+diffCal.get(Calendar.MONTH));
    System.out.println("Years="+(diffCal.get(Calendar.YEAR)-1970));

Answer 5

Check SimpleDateFormat, it has a parse function.