What are the methods of date-time comparison in java
This article will explain in detail the methods of date and time comparison in java. The editor thinks it is very practical, so I share it with you for reference. I hope you can get something after reading this article.
1. Date.compareTo ()
Java.util.Date provides a classic method, compareTo (), to compare two dates in Java.
If the two dates are equal, the return value is 0.
If Date is after the date parameter, the return value is greater than 0.
If Date precedes the date parameter, the return value is less than 0.
@ Test
Void testDateCompare () throws ParseException {
SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd")
Date date1 = sdf.parse ("2009-12-31")
Date date2 = sdf.parse ("2019-01-31")
System.out.println ("date1:" + sdf.format (date1))
System.out.println ("date2:" + sdf.format (date2))
If (date1.compareTo (date2) > 0) {
System.out.println ("Date1 time is after Date2")
} else if (date1.compareTo (date2))
< 0) { System.out.println("Date1 时间在 Date2 之前"); } else if (date1.compareTo(date2) == 0) { System.out.println("Date1 时间与 Date2 相等"); } else { System.out.println("程序怎么会运行到这里?正常应该不会"); } } 输出结果： date1 : 2009-12-31 date2 : 2019-01-31 Date1 时间在 Date2 之前
2. Date.before (), Date.after () and Date.equals ()
A semantically friendly way to compare two java.util.Date
@ Test
Void testDateCompare2 () throws ParseException {
SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd")
Date date1 = sdf.parse ("2009-12-31")
Date date2 = sdf.parse ("2019-01-31")
System.out.println ("date1:" + sdf.format (date1))
System.out.println ("date2:" + sdf.format (date2))
If (date1.after (date2)) {
System.out.println ("Date1 time is after Date2")
}
If (date1.before (date2)) {
System.out.println ("Date1 time is before Date2")
}
If (date1.equals (date2)) {
System.out.println ("Date1 time equals Date2")
}
}
Output result
Date1: 2009-12-31
Date2: 2019-01-31
Date1 time is before Date2
3. Calender.before (), Calender.after () and Calender.equals ()
Compare two Date dates using java.util.Calendar
@ Test
Void testDateCompare3 () throws ParseException {
SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd")
Date date1 = sdf.parse ("2009-12-31")
Date date2 = sdf.parse ("2019-01-31")
System.out.println ("date1:" + sdf.format (date1))
System.out.println ("date2:" + sdf.format (date2))
Calendar cal1 = Calendar.getInstance ()
Calendar cal2 = Calendar.getInstance ()
Cal1.setTime (date1)
Cal2.setTime (date2)
If (cal1.after (cal2)) {
System.out.println ("Date1 time is after Date2")
}
If (cal1.before (cal2)) {
System.out.println ("Date1 time is before Date2")
}
If (cal1.equals (cal2)) {
System.out.println ("Date1 time equals Date2")
}
}
Output result:
Date1: 2009-12-31
Date2: 2019-01-31
Date1 time is before Date2
4. Java 8 date comparison method
In Java 8, you can use the new isBefore (), isAfter (), isEqual (), and compareTo () to compare LocalDate,LocalTime and LocalDateTime. The following example compares two java.time.LocalDate
@ Test
Void testDateCompare4 () throws ParseException {
DateTimeFormatter sdf = DateTimeFormatter.ofPattern ("yyyy-MM-dd")
LocalDate date1 = LocalDate.of (2009, 12, 31)
LocalDate date2 = LocalDate.of (2019, 1,31)
System.out.println ("date1:" + sdf.format (date1))
System.out.println ("date2:" + sdf.format (date2))
System.out.println ("Is...")
If (date1.isAfter (date2)) {
System.out.println ("Date1 time is after Date2")
}
If (date1.isBefore (date2)) {
System.out.println ("Date1 time is before Date2")
}
If (date1.isEqual (date2)) {
System.out.println ("Date1 time equals Date2")
}
}
Output result
Date1: 2009-12-31
Date2: 2019-01-31
Is...
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