Java Date Format Conversion - Getting Wrong Month

Java date format conversion - getting wrong month

Your fromFormat uses minutes where it should use months.

String fromFormat = "yyyy-MM-dd";

simple date format giving wrong month

Change the first format to

SimpleDateFormat tempFormat = new SimpleDateFormat("yyyy-MM-dd");

as DD is the day in the year. 22 is definitely in January

Getting wrong month when using SimpleDateFormat.parse

Use:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

Use MM for month, mm for minutes as stated by documentation...

If you want to print a Date in a specific format, you should use:

 sdf.format(birthday)

or another SimpleDateFormat if you want to pring it in a different format...

Java parse date string returns wrong month

This is due to the format you used as "yyyy-MM-DD". The parser will parse in the sequence way:

• Your input value is "2018-03-08"
• yyyy - will bring to the year 2018
• MM - will bring to the month MARCH

But what is DD? It's the number of the days from the beginning of the year.
So here it moved back to 8^th day on this year (2018) which means January 8^th.

That's why you are seeing January instead of March.

Why is SimpleDateFormat parsing Date with wrong Month and Day?

DD is wrong. D is day of year. Sixth day of year is January 6.

You should use dd.

Docs: SimpleDateFormat

DateFormat pattern dd/MM/yyyy accept wrong months

This should fix it:

df.setLenient(false);

But please look at other date types like LocalDate or ZonedDate. Much easier down the road ;)

strftime('%m',date) returns wrong month value only for 2 months

sqlite doesn't have DateTime data type. So your storing date as strings. Your also filtering in your query using Date strings (by comparing to DateTime string). For the queries date arguments, you are using YYYY-MM-DD format while for storage your using YYYY-MM-DD hh:mm:ss. This is a string comparison and such an inconsistent comparison may yield unexpected results.

I would recommend:

1. You use date() in sqlite to follow a consistent date format to compare the date strings.

Or better

2. Use TypeConverter in Roomand store dates in a format like long and use that for comparison.

Java SimpleDateFormat not detecting month

You are using the wrong date format string: DD (day in year) instead of dd (day in month). Change both SimpleDateFormat instance to use dd:

DateFormat inputFormat = new SimpleDateFormat("yyyyMMddhhmmss");
DateFormat outputFormat = new SimpleDateFormat("YYYY-MM-dd'T'hh:mm:ss'Z'");

Therefore you are getting the wrong result.

SimpleDateFormat parsing wrong date

tl;dr

myJavaUtilDate 
.toInstant()
.atZone
(
    ZoneId.of( "Asia/Kolkata" ) 
)
.toLocalDate()
.isEqual
(
    LocalDate
    .parse
    (
        "03/10/2020" ,                              // Do you mean March 10th, or October 3rd? 
        DateTimeFormatter.ofPattern( "dd/MM/uuuu" ) // Or "MM/dd/uuuu".
    )
)

Smart objects, not dumb strings

You said:

make 3 dates of the same format so that I can compare them

Use objects with comparison methods, rather than comparing text of strings.

We have a class for dates built into Java: LocalDate.

java.time

You are using Date which is one of the terrible date-time classes bundled with the earliest versions of Java. These classes are now obsolete, supplanted years ago with the adoption of JSR 310 that defines the java.time classes.

I have passed a date

When encountering a java.util.Date object, immediately convert to its modern replacement, java.time.Instant. Use the new conversion method toInstant added to the old class.

Instant instant = myJavaUtilDate.toInstant() ;

Both java.util.Date and java.time.Instant represent a moment in UTC. Is that how you want to perceive the date, in UTC with an offset of zero hours-minutes-seconds from the prime meridian? Keep in mind that for any given moment the date varies around the globe by zone. A moment may be "tomorrow" in Tokyo Japan while still "yesterday" in Toledo Ohio US.

OffsetDateTime odt = instant.atOffset( ZoneOffset.UTC ) ;

Extract the date.

LocalDate ld = odt.toLocalDate() ;  // Extract the date only, omitting the time-of-day and the offset-from-UTC.

Or did you want to perceive that date in a particular zone?

ZoneId z = ZoneId.of( "Asia/Tokyo" ) ;
ZonedDateTime zdt = instant.atZone( z ) ;
LocalDate ld = zdt.toLocalDate() ;  // Extract the date only, omitting the time-of-day and the zone.

and two string to a function

Define a formatting pattern to match your inputs.

String input = "03/10/2020" ;
DateTimeFormatter f = DateTimeFormatter.ofPattern( "dd/MM/uuuu" ) ;
LocalDate ld = LocalDate.parse( input , f ) ;  // Throws `DateTimeParseException` if input is faulty.

Now compare, using methods isEqual, isAfter, isBefore.

boolean datesMatch = ld1.isEqual( ld2 ) && ld2.isEqual( ld3 ) ;

java.util.Date::toString tells a lie

You asked:

D2 = sat Oct 03 00:00:00 IST 2020 //wrong date fdate was 03/10/2020

Can anyone tell where did I go wrong?

Your main problem is that your formatting pattern is not defined to match your intention. This is correctly identified in the Answer by Chris and the Answer by Arvind Kumar Avinash.

In addition, you have another issue. Among the many problems with java.util.Date is that its toString method on-the-fly applies the JVM’s current default time zone while generating text to represent the content of the object. This creates the illusion of that zone being stored within the object. When perceiving your Date object’s UTC value after adjusting to a time zone, the date may differ from the date as seen in UTC. This was discussed above.

➥ Never use java.util.Date.

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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.

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

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

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - 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
  
  • Most 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 (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….

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