How to compare two Dates without the time portion?

java

date-comparison

time-zone

date-library

byNikita Barsukov·Aug 31, 2024

Compare two java.util.Date instances sans time with SimpleDateFormat or java.time.LocalDate in Java 8+.

Code Snippet:

// With SimpleDateFormat
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
// "May the "force" be with you, but only the date, not the time
boolean datesEqual = sdf.format(date1).equals(sdf.format(date2));

// With LocalDate (Java 8+)
LocalDate ld1 = date1.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();
LocalDate ld2 = date2.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();
// Reality can be whatever I want, and I want just the dates
boolean datesEqual = ld1.isEqual(ld2);

Pick your tool: Libraries for date comparison

Selecting an appropriate library can substantially simplify date comparison and leverage robustness. Here are some mainstream libraries with date comparison benefits.

Joda Time: Time-zone aware comparison

Joda Time offers an efficient date comparison approach considering time zones and daylight saving time.

Dependency add for Android project:

implementation 'net.danlew:android.joda:2.10.9.1' // The Joda way or the highway!

Code Snippet using Joda-Time:

DateTimeComparator comparator = DateTimeComparator.getDateOnlyInstance();
// "I see no time, only dates" - Joda Time
boolean datesEqual = comparator.compare(dateTime1, dateTime2) == 0;

Calendar Method: The Time bandit

The standard Java Calendar can be used for comparison by setting the time fields to zero.

Code Snippet:

Calendar cal1 = Calendar.getInstance();
Calendar cal2 = Calendar.getInstance();
cal1.setTime(date1);
cal2.setTime(date2);
cal1.set(Calendar.HOUR_OF_DAY, 0); // "I don't have time for this!" - Calendar
cal1.set(Calendar.MINUTE, 0);
cal1.set(Calendar.SECOND, 0);
cal1.set(Calendar.MILLISECOND, 0);
cal2.set(Calendar.HOUR_OF_DAY, 0);
// Repeat for MINUTE, SECOND, MILLISECOND
boolean datesEqual = cal1.equals(cal2);

Apache Commons: For a day in the life

DateUtils.isSameDay from Apache Commons Lang provides brevity in day comparison..

Code Snippet:

boolean datesEqual = DateUtils.isSameDay(date1, date2); // Not a date's worth of difference!

Comprehensive dissection of date comparison

Here's a detailed walkthrough of the nuances to aid any scenario you encounter.

Leap Year and DST: Tricky calendars

Be mindful of leap years or Daylight Saving Time (DST). java.time or Joda-Time handle these smoothly.

Performance: The need, the need for speed

Large volumes of dates require efficient algorithms. Pick methods proportional to the task's magnitude.

Utility method: If it fits, I sit

Repeated comparison closets? Go for an utility method abstraction!

Code Snippet:

public static boolean areDatesEqual(Date date1, Date date2) {
    // "Duplicity breeds chaos. Let's streamline!"
    return // implement any of the above comparison methods...
}