CODEWITHSUNDEEP
javadatecalendar
user2891462
user2891462

Reputation: 3333

How to check if a certain date is passed

I have a string of the form "mm/yyyy" and I want to compare it against the date of the local system.

I have thought of either using a conversion table between my month and the MONTH field in Calendar, something like:

    Calendar cal = Calendar.getInstance();
    String date = "07/2014";
    String month = date.subString(0, 2);
    int monthToCompare;
    if (month.equals("01"))
      monthToCompare = cal.JANUARY;
    if (month.equals("02"))
      monthToCompare = cal.FEBRUARY;
    ...

And then comparing manually with an if. I don't like it because I think is way too long for such a simple operation.

The other option I've thought of is getting the current Date() and using the before() method. That would mean translating my date to the Date format, but the easy methods to do it are deprecated, I must specify the number of milliseconds and I do not know how to easily do that (taking into consideration leap years, calendar corrections and so on since 1970).

Upvotes: 24

Views: 62551

Answers (5)

Ummer Siddique
Ummer Siddique

Reputation: 395

You can use following kotlin extension function for this.

/**
 * Checks if the string represents a date that is expired.
 *
 * This function parses the string as a date in the format "yyyy-MM-dd" using the UK locale,
 * then compares it to the current date. If the parsed date is before the current date,
 * it is considered expired.
 *
 * @return `true` if the string represents a date that is expired or if parsing fails,
 * `false` otherwise.
 */
fun String.isExpired(): Boolean {
    return try {
        val format = SimpleDateFormat("yyyy-MM-dd", Locale.UK)
        // Return true if parsing fails (assuming expired)
        val parsedDate = format.parse(this) ?: return true
        parsedDate.before(Date())
    } catch (e: Exception) {
        // Handle parsing exception (e.g., invalid date format)
        true  // Consider returning null or throwing a custom exception for specific handling
    }
}

Upvotes: 0

user2891462
user2891462

Reputation: 3333

Using @Mifmif answer I finally solved the problem with:

if (new SimpleDateFormat("MM/yyyy").parse(date).before(new Date())) {
    ...
}

Upvotes: 53

Javac Ds
Javac Ds

Reputation: 21

 //getting current date

private String getDateTime() {           

    DateFormat dateFormat = new SimpleDateFormat("dd-MMM-yyyy", Locale.getDefault());

    Date date = new Date();

    return dateFormat.format(date);
}


//compare the dates

Date date1  = new Date("second_date to be compared");

Date date2 = new Date(getDateTime());


if(date1.before(date2)) {

     Log.d("Date already passed", " " + "second_date");
}

Upvotes: 2

Basil Bourque
Basil Bourque

Reputation: 338730

tl;dr

YearMonth.parse( 
    "07/2014" , 
    DateTimeFormatter.ofPattern( "MM/uuuu" )
).isAfter(
    YearMonth.now(
        ZoneId.of( "Africa/Tunis" )
    )
)

java.time

The modern solution uses the java.time classes rather than the troublesome old date-time classes.

Year & month only

To represent an entire month, use the YearMonth class. 

String input = "07/2014" ; 
DateTimeFormatter f = DateTimeFormatter.ofPattern( "MM/uuuu" ) ;
YearMonth ym = YearMonth.parse( input , f ) ;

Tips: Use such YearMonth objects throughout your codebase rather than a mere string. And when you do need a string to exchange data, use standard ISO 8601 format: YYYY-MM. The java.time classes use standard formats by default when parsing/generating strings, so no need to define formatting pattern.

Current year-month

Determining the current year-month means determining the current date.

A time zone is crucial in determining a date. For any given moment, the date varies around the globe by zone. For example, a few minutes after midnight in Paris France is a new day while still “yesterday” in Montréal Québec.

If no time zone is specified, the JVM implicitly applies its current default time zone. That default may change at any moment, so your results may vary. Better to specify your desired/expected time zone explicitly as an argument.

Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!). 

ZoneId z = ZoneId.of( "America/Montreal" ) ;  
LocalDate today = LocalDate.now( z ) ;

If you want to use the JVM’s current default time zone, ask for it and pass as an argument. If omitted, the JVM’s current default is applied implicitly. Better to be explicit, as the default may be changed at any moment during runtime by any code in any thread of any app within the JVM.

ZoneId z = ZoneId.systemDefault() ;  // Get JVM’s current default time zone.

Same idea applies to getting the current YearMonth: pass a ZoneId.

YearMonth currentYearMonth = YearMonth.now( z ) ;

Compare

Compare using methods isBefore, isAfter, and equals. 

boolean isAfterCurrentYearMonth = ym.isAfter( currentYearMonth ) ;

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?

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.

Upvotes: 5

Mifmif
Mifmif

Reputation: 3190

Try this :

new SimpleDateFormat("MM/yyyy").parse("07/2014").compareTo(new Date());

Upvotes: 8

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