how to check if one date is after another in java?

Question

I am taking in two dates as command line arguments and want to check if the first one is after the second date. the format of the date it "dd/MM/yyy". Example: java dateCheck 01/01/2014 15/03/2014 also i will need to check if a third date hardcoded into the program is before the second date.

Answer 1

try {
    System.out.println("Enter first date : (dd/MM/yyyy)");
    BufferedReader bufferRead = new BufferedReader(new InputStreamReader(System.in));
    SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
    Date date1 = sdf.parse(bufferRead.readLine());
    System.out.println("Enter second date : (dd/MM/yyyy)");
    Date date2 = sdf.parse(bufferRead.readLine());
    System.out.println(date1 + "\n" + date2);
    if (date1.after(date2)) {
        System.out.println("Date1 is after Date2");
    } else {
            System.out.println("Date2 is after Date1");
    }
} catch (IOException e) {
    e.printStackTrace();
}

Answer 2

To compare two dates :

            SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyy");

            Date firstDate = sdf.parse("01/01/2014");
            Date secondDate = sdf.parse("15/03/2014");

            if(firstDate.before(secondDate)){
                System.out.println("firstDate <  secondDate");
            }
            else if(firstDate.after(secondDate)){
                System.out.println("firstDate >  secondDate");
            }
            else if(firstDate.equals(secondDate)){
                System.out.println("firstDate = secondDate");
            }

Answer 3

Use SimpleDateFormat to convert a string to Date.

SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
Date date1 = sdf.parse("01/01/2017");

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 */ 
}

Answer 4

tl;dr

LocalDate ld1 = LocalDate.parse( "01/01/2014" , DateTimeFormatter.ofPattern( "dd/MM/uuuu" ) ) ;
LocalDate ld2 = LocalDate.parse( "15/03/2014" , DateTimeFormatter.ofPattern( "dd/MM/uuuu" ) ) ;
LocalDate ld3 = LocalDate.of( 2014 , Month.JULY , 1 ) ;

Boolean isFirstDateBeforeSecondDate = ld1.isBefore( ld2 ) ;
Boolean isThirdDateBeforeSecondDate = ld3.isBefore( ld2 ) ;

Boolean result = ( isFirstDateBeforeSecondDate && isThirdDateBeforeSecondDate ) ;

return result ;

Using java.time

The modern approach uses the java.time classes rather than the troublesome old legacy date-time classes (Date, Calendar, etc.).

The LocalDate class represents a date-only value without time-of-day and without time zone.

Define a formatting pattern to match your input strings using the DateTimeFormatter class.

String input = "15/03/2014" ;
DateTimeFormatter f = DateTimeFormatter.ofPattern( "dd/MM/uuuu" );
LocalDate ld = LocalDate.parse( input , f );

ld.toString(): 2014-03-15

To specify a fixed date, pass year, month, and dayOfMonth. For the month, you may specify a number, sanely numbered 1-12 for January-December (unlike the crazy 0-11 in the legacy classes!). Or you may choose to use the Month enum objects.

LocalDate firstOf2014 = LocalDate.of( 2014 , Month.JANUARY , 1 );

Compare using isBefore, isEqual, or isAfter methods.

Boolean isInputDateBeforeFixedDate = ld.isBefore( firstOf2014 ) ;

isInputDateBeforeFixedDate.toString(): false

ISO 8601

If possible, replace your particular date string format with the standard ISO 8601 format. That standard defines many useful practical unambiguous string formats for date-time values.

The java.time classes use the standard formats by default when parsing/generating strings. You can see examples in the code above. For a date-only value, the standard format is YYYY-MM-DD.

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About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, and later
  • Built-in.
  • Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
  • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
  • See How to use ThreeTenABP….

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

Answer 5

To read a date and check before:

SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyy");
try {
    Date date1 = sdf.parse(string1);
    Date date2 = sdf.parse(string2);
    if(date1.before(date2)) {
       // do something
    }
} catch(ParseException e) {
    // the format of the read dates is not the expected one
}