How to Compare Dates in Java

How to compare dates in Java?

Date has before and after methods and can be compared to each other as follows:

if(todayDate.after(historyDate) && todayDate.before(futureDate)) {
    // In between
}

For an inclusive comparison:

if(!historyDate.after(todayDate) && !futureDate.before(todayDate)) {
    /* historyDate <= todayDate <= futureDate */ 
}

You could also give Joda-Time a go, but note that:

Joda-Time is the de facto standard date and time library for Java prior to Java SE 8. Users are now asked to migrate to java.time (JSR-310).

Back-ports are available for Java 6 and 7 as well as Android.

How to compare two string dates in Java?

Convert them to an actual Date object, then call before.

SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd h:m");
System.out.println(sdf.parse(startDate).before(sdf.parse(endDate)));

Recall that parse will throw a ParseException, so you should either catch it in this code block, or declare it to be thrown as part of your method signature.

How to compare two dates along with time in java

Since Date implements Comparable<Date>, it is as easy as:

date1.compareTo(date2);

As the Comparable contract stipulates, it will return a negative integer/zero/positive integer if date1 is considered less than/the same as/greater than date2 respectively (ie, before/same/after in this case).

Note that Date has also .after() and .before() methods which will return booleans instead.

How to compare dates in Java using comparison operators?

LocalDate date1 = LocalDate.of(2017, 10, 30); // Year, month, day.
LocalDate date2 = LocalDate.of(2017, 10, 31);
LocalDate date3 = LocalDate.of(2018, 10, 30);

System.out.printf("%s before %s? %s%n", date1, date2, date1.isBefore(date2));
System.out.printf("%s before %s? %s%n", date2, date3, date3.isBefore(date3));
System.out.printf("%s before %s? %s%n", date3, date1, date3.isBefore(date1));

If you want to know how to do a comparison yourself:

Compare first year, then month, then day: from most significant to least
For this reason the ISO standard of denoting dates (and times) is 2017-09-30T13:05:01,000 where a text comparison with a representation of the same length suffices.

And the pattern goes:

if years not equal then result found
if months not equal then result found
result is comparison of days

Comparing dates as strings in Java

Since your dates are in the YYYY-MM-DD format, a lexicographic comparison can be used to determine the ordering between two dates. Thus, you can just use the String.compareTo() method to compare the strings:

int c1 = objectDate.compareTo(dateOne);
int c2 = objectDate.compareTo(dateTwo);
if ((c1 >= 0 && c2 <= 0) || (c1 <= 0 && c2 >= 0)) {
    // objectDate between dateOne and dateTwo (inclusive)
}

If it is guaranteed that dateOne < dateTwo, then you can just use (c1 >= 0 && c2 <= 0). To exclude the date bounds, use strict inequalities (> and <).

How to compare two dates in String format?

For a more generic approach, you can convert them both to Date objects of a defined format, and then use the appropriate methods:

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

Date date1 = format.parse(date1);
Date date2 = format.parse(date2);

if (date1.compareTo(date2) <= 0) {
    System.out.println("earlier");
}

Java Date comparison: Dates in different formats

tl;dr

LocalDate
.parse( "2018-08-29" ) 
.isEqual(
    OffsetDateTime
    .parse( "2018-08-30T00:00:00+10:00" )
    .toLocalDate()
)

false

java.time

Parse each input during its appropriate type in java.time.

LocalDate ld = LocalDate.parse( "2018-08-29" ) ;
OffsetDateTime odt = OffsetDateTime.parse( "2018-08-30T00:00:00+10:00" ) ;

Compare by extracting a LocalDate from the OffsetDateTime.

Boolean sameDate = ld.isEqual( odt.toLocalDate() ) ;

false

Or perhaps you want to adjust that OffsetDateTime from its offset of ten hours ahead of UTC to another offset or time zone. For example, let’s adjust back to UTC before extracting a date to compare.

LocalDate
.parse( "2018-08-29" ) 
.isEqual(
    OffsetDateTime
    .parse( "2018-08-30T00:00:00+10:00" )
    .withOffsetSameInstant( ZoneOffset.UTC )
    .toLocalDate()
)

This changes our results from false, seen in code above, to true.

true

Comparing dates in Java

Java has a Date object. You should be using that instead.

import java.util.Calendar;
import java.util.Date;

public class CompareDates {

    public static void main(String[] args) {
        // Create a calendar, this will default to today
        Calendar cal = Calendar.getInstance();
        // Subtract 1 day
        cal.add(Calendar.DATE, -1);
        // Compare the result (1)
        System.out.println(dateCompare(new Date(), cal.getTime()));
        // Add 2 days
        cal.add(Calendar.DATE, 2);
        // Compare the result (-1)
        System.out.println(dateCompare(new Date(), cal.getTime()));            
    }

    public static int dateCompare(Date today, Date date2) {
        System.out.println("Compare " + today + " with " + date2);
        return today.compareTo(date2);
    }
}

You could also just make use of the Date API and use before and after...

Date now = new Date();

Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -1);
System.out.println(now + " isBefore " + cal.getTime() + " = " + now.before(cal.getTime()));
System.out.println(now + " isAfter " + cal.getTime() + " = " + now.after(cal.getTime()));
cal.add(Calendar.DATE, 2);
System.out.println(now + " isBefore " + cal.getTime() + " = " + now.before(cal.getTime()));
System.out.println(now + " isAfter " + cal.getTime() + " = " + now.after(cal.getTime()));