How to check if a certain date is passed

Question

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).

Antiseptic

I said I know about those two methods, and that I do not know how to create a Date object to compare with from a String. – Antiseptic

Have you looked at DateFormat.parse()? – Geomancer

Duplicate: Java string to date conversion – Sarmentose

FYI, the troublesome old date-time classes such as java.util.Date, java.util.Calendar, and java.text.SimpleDateFormat are now legacy, supplanted by the java.time classes built into Java 8 & Java 9. See Tutorial by Oracle. Tip: YearMonth class. – Sarmentose

Re-opening as I noticed the Question here is starts with only a year-month rather than a full date. Different from the duplicates we marked. – Sarmentose

Answer 1

Using @Mifmif answer I finally solved the problem with:

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

Antiseptic

This solved my problem in single line. – Indogermanic

Answer 2

Try this :

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

Standup

It seems unlikely his goal is to know if it happens to be exactly midnight and zero milliseconds on the first of the month..... – Extravert

Answer 3

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?

• 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
  • Later versions of Android bundle implementations of the java.time classes.
  • For earlier Android, the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). 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.

Sarmentose

Answer 4

 //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");
}

Midpoint

Thanks for wanting to contribute. Please don’t teach the young ones to use the long outdated and notoriously troublesome SimpleDateFormat class. At least not as the first option. And not without any reservation. Today we have so much better in java.time, the modern Java date and time API and its DateTimeFormatter. Yes, you can use it on Android. For older Android see How to use ThreeTenABP in Android Project. – Jeanicejeanie

For me SimpleDateFormat with Date works great. I had very bad experience with Calendar. On some devices the dates where going crazy using Calendar. – Monseigneur

Answer 5

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
    }
}

Indogermanic